US3872345A - Colour picture tubes - Google Patents

Colour picture tubes Download PDF

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Publication number
US3872345A
US3872345A US408938A US40893873A US3872345A US 3872345 A US3872345 A US 3872345A US 408938 A US408938 A US 408938A US 40893873 A US40893873 A US 40893873A US 3872345 A US3872345 A US 3872345A
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United States
Prior art keywords
effective area
colour
perforations
picture tube
colour picture
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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
US408938A
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English (en)
Inventor
Eiichi Yamazaki
Akio Yamaguchi
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Hitachi Ltd
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Hitachi Ltd
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    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J19/00—Details of vacuum tubes of the types covered by group H01J21/00
    • H01J19/28—Non-electron-emitting electrodes; Screens
    • H01J19/32—Anodes
    • H01J19/36—Cooling of anodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2893/00—Discharge tubes and lamps
    • H01J2893/0001—Electrodes and electrode systems suitable for discharge tubes or lamps
    • H01J2893/0012—Constructional arrangements
    • H01J2893/0027—Mitigation of temperature effects

Definitions

  • ABSTRACT In a colour picture tube having a colour selection electrode disposed to oppose the fluorescent screen of the tube and having an effective area provided with a plurality of perforations for transmitting electron beams, the effective area of the colour selection electrode is provided with a compensating mechanism for absorbing local thermal expansion of the effective area thereby preventing the deformation thereof.
  • This invention relates to a colour picture tube, more particularly to a colour selection electrode of a colour picture tube.
  • colour selection electrodes for use in colour picture tubes are included various types such as a shadow mask provided with a plurality of circular perforations for transmitting electron beams, a stripe mask provided with elongated openings or slits for transmitting electron beams or a grid type mask in which metal wires are secured to a frame.
  • the colour selection electrode to which the invention is applicable has a construction wherein a plurality of perforations for transmitting electron beams in the form of regularly ar ranged circular, oblong or rectangular openings are provided for a plate, such as the shadow mask and stripe mask described above.
  • the invention will be described in connection with a colour selection electrode in the form of a shadow mask.
  • the so-called shadow mask type colour picture tube utilizing a shadow mask usually comprises an evacuated envelope including a panel, a funnel and neck, a fluorescent screen formed on the inner surface of the panel, a shadow mask, that is a colour selection electrode, spaced apart a predetermined distance from the fluorescent screen, and an electron gun assembly contained in the neck.
  • the electron beams emitted by the electron gun assembly are deflected by a deflection coil surrounding the envelope and selected by the shadow mask for different colours.
  • the electron beams transmitting through the shadow mask are caused to impinge upon predetermined phosphor dots on the fluorescent screen, thus causing the dots to fluoresce.
  • bimetals The purpose of the bimetals, however, is to provide a compensation when the assembly of the shadow mask and the supporting frame undergoes thermal expansion as an integral unit so that it is impossible to perfectly compensate for the colour mismatch by such measure.
  • the thermal expansion of the shadow mask is substantially constant over its entire surface so that it is possible to perfectly compensate for the colour mismatch by using bimetals for mounting the shadow mask on the supporting frame.
  • the density of current flowing into the shadow mask is different from point to point with the result that a portion of the shadow mask expands locally.
  • the surface of the shadow mask which is shaped to a predetermined curved surface and provided with a plurality of perforations for transmitting electron beams is deformed to depart from said predetermined curved surface.
  • the bimetals described above is useless to compensate for this phenomenon.
  • the deformation caused by the local expansion of mask face or the effective area of the shadow mask is temporal in one case whereas it is permanent in the other case. In the latter case, the colour mismatch occurs always irrespective to the temperature condition of the shadow mask which is detrimental to the colour picture tube.
  • a further object of this invention is to provide a novel compensating mechanism which is easy to manufacture and capable of preventing the deformation of the effective area of the colour selection electrode caused by local thermal expansion.
  • a colour picture tube of the class comprising an evacuated envelope, a fluo rescent screen disposed in the envelope, a colour selection electrode disposed to oppose the fluorescent screen and including an effective area provided with a plurality of perforations for transmitting electron beams, and an electron gun assembly, characterized-by a compensating mechanism provided for the effective area of the colour selection electrode for absorbing local thermal expansion of the effective area thereby preventing deformation thereof.
  • the compensating mechanism can be most conveniently formed by corrugating the effective area or by providing bottomed slits for the' effective area, the bottomed slits extending towards each other from the opposite surfaces of the effective area.
  • FIG. 1 is a side view, partly broken away, of one example of a prior art colour picture tube illustrated for the purpose of explaining the deformation of the effective area of the colour selection electrode;
  • FIG. 2 is an enlarged sectional view of a portion of the tube shown in FIG. 1;
  • FIGS. 3A and 3B are diagrams to compare the deformation of the effective area of the prior art construction and of a shadow mask embodying the invention caused by local thermal expansion;
  • FIG. 4 shows a perspective view of a portion of one example of the compensating mechanism utilized in the colour picture tube of this invention
  • FIGS. 5A and 5B are enlarged views of a portion of the compensating mechanism shown in FIG. 4;
  • FIG. 6A shows a plan view of a modified example of the compensating mechanism utilized in the colour picture tube of this invention
  • FIG. 6B shows a cross-sectional view taken along a line VI-VI shownin FIG. 6A;
  • FIG. 6C is a diagram showing the relationship between the compensating mechanism shown in FIG. 6A and the perforations thereof for transmitting electron beams.
  • FIG. 7 is a partial cross-sectional view of the shadow mask provided with the compensating mechanism shown in FIG-6A which is helpful to explain the deformation of the effective area of the shadow mask caused by thermal expansion;
  • FIG. 8A is a plan view showing another example of the compensating mechanism utilized in the colour picture tube of this invention.
  • FIG. 8B is a sectional view taken along a line VIII- VIlI shown in FIG. 8A and FIG. 9 is a partial plan view showing another arrangement of the perforations for transmitting electron beams.
  • a priorart colour picture tube shown in FIG. 1 comprises an evacuated envelope including a panel 2, a funnel 3, and a neck 4.
  • a fluorescent screen 5 On the inner surface of the panel 2 is formed a fluorescent screen 5 and a colour selection electrode 6 shown as a shadow mask is mounted on a supporting frame 7 and is disposed close to the fluorescent screen 5.
  • the supporting frame 7 and the shadow mask 6 supported'thereby are secured to the inner wall of the funnel 3 by means of a plurality of supporting members 8 in the form of bimetals or members including bimetals at one portion thereof, one end of each supporting member 8 being secured to the supporting frame 7 and the other end being provided with an opening (not shown) for receiving a pin 9 secured to the inner side of the funnel.
  • an electron gun assembly 10 is contained in the neck 4 to emit electron beams 11 which transmit through perforations 6a provided for the shadow mask 6 to impinge upon the desired phosphor dots (not shown) formed on the fluorescent screen 5, thus causing the phosphor dots to luminesce.
  • a deflection coil 12 is mounted on the outside of the envelope 1.
  • a plurality of perforations 6a for transmitting the electron beams are provided for the effective area 13 of the shadow mask 6, it being understood that such perforations are not provided for the periphery 15 of the shadow mask between its effective area 13 and a skirt 15.
  • Dotted lines 16 show the local thermal expansion of the effective area.
  • the electron beams 11 emitted from the electron gun assembly 10 are deflected by deflection coil 12 to transmit through selected one of the perforations 6a of the shadow mask to impinge upon desired phosphor dots on the fluorescent screen.
  • the shadow mask 6 will undergo substantially uniform thermal expansion. Accordingly, it is possible to provide substantially perfect compensation for colour mismatch by the action of the bimetallic supporting members.
  • FIGS. 3A dnd 38 the unidimensional deformation due to local thermal expansion of a curved surface with its opposite ends held stationary will be discussed. It is supposed now that a portion 1 of a uniformely curved surface maintained at a predetermined temperature is deformed by h to a position l due to local thermal expansion as shown in FIG. 3A.
  • a corrugated curved surface shown in FIG. 3B made of the same material and maintained at the same temperature as the curved surface shown in FIG. 3A undergoes local thermal expansion, the curved surface will expand until the total sum of micro arcuate lengths of respective curved surfaces becomes equal to the length of an are 1 shown in FIG. 3A, the extent of deformation h of the effective area in this case being much smaller than h in the previous case.
  • the colour selection electrode of this invention is provided with the corrugation or an equivalent compensating mechanism at the effective area thereof.
  • FIG. 4 shows one example of the shadow mask provided with the compensating mechanism of this invention, in which shadings are applied on the assumption that the light is projected from the upper right.
  • the effective area 23 of the shadow mask 26 shown in FIG. 4 is shaped to have a wavy configuration which when viewed normal to the mask surface appears as a corrugated surface of contiguous concave-convex areas to provide a compensating mechanism 19 free to expand and contract two dimensionally. More particularly, in the compensating mechanism 19, all lines la interconnecting points a are at the same level and all lines 1b interconnecting points b are also at the same level, the lines 1a being positioned at the tops whereas lines 1b at the valleys. Accordingly, points b are positioned at lower levels than points a.
  • the pitch of the corrugations is determined by taking into such factors as the size of the effective area 23, the radius of curvature thereof, and the maximum operating temperature.
  • FIGS. 5A and 5B show a plan view and a side view of the compensating mechanism shown in FIG. 4.
  • g represents the distance between points a
  • a h the height of the top, that is the vertical height between points a and b and f the distance between points b and b
  • h will bevaried to h, meaning that it is possible to vary distances g and f without creating any appreciable internal stress.
  • g and f increase. In other words, even when there is a tendency of increasing g and f due to thermal expansion, if the periphery of the effective area is held stationary, only the height varies.
  • the inclination angle of oblique lines lab interconnecting points a and b is very small and the length of the line lab is of the order of 0.6 mm.
  • the local deformation, or the distance it, shown in FIG. 3A, due to local heating of a shadow mask not provided with any compensating mechanism is about 0.2 to 0.3 mm, whereas in the shadow mask provided with the compensating mechanism it is possible to reduce the height h by several orders of magnitude.
  • the perforations for transmitting electron beams may be provided at points a or in the inclined surfaces bounded by oblique lines lab interconnecting points a and b. However, it is advantageous to locate the perforations at points a in order to facilitate bending of the effective area along the top and bottom edges as well as the oblique lines lab.
  • the illustrated compensating mechanism 19 can be readily formed by a press work, for example.
  • FIGS. 6A, 6B and 6C show an effective area of the shadow mask provided with a modified compensating mechanism.
  • the modified compensating mechanism 39 comprises bottomed slits 34 at portions of the shadow mask 36 corresponding to the top and bottom edges and the oblique lines shown in FIG. 4, the slits extending inwardly from the opposite surfaces of the effective area 33.
  • this modified compensating mechanism has substantially the same function as that shown in FIG. 4 although its construction is simpler.
  • the slits 34 act as the absorber of expansion to permit free expansion and contraction it is possible to prevent any appreciable deformation of the effective area 33.
  • the width of the perforations'35 for transmitting the electron beams are formed at the intersecting points of respective slits 34.
  • the area of such intermediate portions may be varied to form one, two or more than two perforations in each portion or may be small not to permit provision of a single perforation. The area is determined in accordance with the size of the shadow mask.
  • the perforations 35 are formed at the intersections of the slits for the reason described above. It is advantageous to form the slits 34 concurrently with the perforations for transmitting the electron beams. Generally, the perforations 35 are formed by photoetching technique.
  • FIGS. 8A and 8B illustrate still further modification of the compensating mechanism 49 in which the perforations 45 for transmitting the electron beams are directed in different directions whereas in the example shown in FIG. 6, the perforations 35 are directed in the same direction with their smaller openings opened upwardly. Furthermore, the bottomed slits 44 are provided between adjacent perforations 45.
  • FIG. 9 shows another arrangement of the perforations for transmitting the electron beams wherein shadow mask 5b is a modification of the shadow mask shown in FIG. 4.As shown, a plurality of perforations 55 for transmitting the electron beams are formed in each inclined surface bounded by lines la, lb and lab.
  • the effective area 53 of the shadow mask is corrugated to permit two dimensional expansion and contraction.
  • the length of lines 1a, 1b and lab is preferably to be 0.5 to 50 mm. However, if the length were too long, the compensating effect for local expansion would be decreased.
  • Such modified compensating mechanism can be formed simultaneously. with the shadow mask as by press work.
  • the colour selection electrode is never limited to a shadow mask and that such perforations may be elongated circles or slits, that is a stripe mask.
  • lines la, lb were shown as continuous folds, whereas as slits in the embodiments shown in FIGS. 6A, 6B and 8A, 8B, they may be of any suitable form so long as equivalent effect can be obtained.
  • bottomed perforations having suitable spacings may be formed along said lines or slits.
  • the invention can also be applied to a colour selection electrode not provided with a supporting frame.
  • the invention pro.- vides a colour picture tube provided with an improved colour selection electrode having a compensating mechanism provided for the surface or effective area of the colour selection electrode including a plurality of perforations for transmitting the electron beams, the compensating mechanism functioning to absorb local thermal expansion of the effective area so as to efficiently prevent the effective area from deforming.
  • the compensating mechanism can be formed concurrently with the perforations for transmitting the electron beams, or concurrently with the shaping operation of the colour selection electrode, it is possible to manufacture the compensating mechanism at a low cost.
  • a colour picture tube of the class comprising an evacuated envelope, a fluorescent screen disposed in said envelope, a colour selection electrode disposed to oppose said fluorescent screen and including an effective area provided with a plurality of perforations for transmitting electron beams, and an electron gun assembly
  • the improvement which comprises a compensating mechanism having a corrugated surface of contiguous concave-convex areas substantially constituting said effective area of said colour selection electrode for absorbing local thermal expansion of said effective area thereby preventing deformation of said effective area.
  • said compensating mechanism comprises corrugations formed on said effective area, said corrugations having a plurality of spaced apart top edges on the same curved surface and a plurality of bottom edges parallel to said topedges and positioned intermediate adjacent top edges;
  • said compensating mechanism comprises corrugations formed by shaping said effective area and bottomed slits provided at respective folds of said corrugations, said bottomed slits extending toward each other from the opposite surfaces of said effective area.
  • each of said perforations having a larger opening on one side and a smaller opening on the other side, and said larger openings and smaller openings are disposed alternately on both sides of said effective area.

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US408938A 1972-10-27 1973-10-23 Colour picture tubes Expired - Lifetime US3872345A (en)

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2366687A1 (fr) * 1976-10-04 1978-04-28 Rca Corp Tube a rayons cathodiques du type a masque d'ombre
US4122368A (en) * 1977-07-08 1978-10-24 Rca Corporation Cathode ray tube with a corrugated mask having a corrugated skirt
US4146816A (en) * 1977-07-08 1979-03-27 Rca Corporation Cathode-ray tube with a corrugated mask having a corrugated hinging skirt
US4162421A (en) * 1975-03-19 1979-07-24 Rca Corporation Cathode ray tube having corrugated shadow mask with slits
FR2425718A1 (fr) * 1978-05-11 1979-12-07 Rca Corp Tube a rayons cathodiques comportant un masque d'ombre a forme d'onde variable
US4766341A (en) * 1985-09-18 1988-08-23 Mitsubishi Denki Kabushiki Kaisha Color picture tube with shadow mask having alternately displaced apertures
US5384511A (en) * 1991-09-19 1995-01-24 Mitsubishi Denki Kabushiki Kaisha Varible-thickness shadow mask for color cathode-ray tubes
US6043595A (en) * 1996-11-11 2000-03-28 Kabushiki Kaisha Toshiba Shadow mask having a curved surface with compressed, strengthening dents
US6294863B1 (en) * 1997-12-18 2001-09-25 Kabushiki Kaisha Toshiba Color cathode ray tube having a shadow mask with a plurality of strip shaped reinforcing beads
US6577047B2 (en) * 1999-12-21 2003-06-10 Matsushita Electric Industrial Co., Ltd. Cathode ray tube

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1546889A (en) 1975-03-19 1979-05-31 Rca Corp Cathode ray tube having shadow mask
DE2659998C2 (de) * 1975-03-19 1986-12-18 Rca Corp., New York, N.Y. Kathodenstrahlröhre mit gewellter Farbauswahl-Lochmaske
US4173729A (en) * 1977-06-24 1979-11-06 Rca Corporation Cathode-ray tube having a stepped shadow mask
US4293792A (en) * 1979-12-18 1981-10-06 Rca Corporation Color picture tube having improved slit type shadow mask

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2579665A (en) * 1950-04-29 1951-12-25 Rca Corp Color-kinescopes, etc.
US2863079A (en) * 1955-05-27 1958-12-02 Kendon Electronics Inc Masking devices for color television screen or the like
US3653900A (en) * 1969-08-15 1972-04-04 Zenith Radio Corp Selective etching process for changing shadow-mask aperture size
US3772555A (en) * 1972-03-30 1973-11-13 Gte Sylvania Inc Color cathode ray tube of the shadow mask variety

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2579665A (en) * 1950-04-29 1951-12-25 Rca Corp Color-kinescopes, etc.
US2863079A (en) * 1955-05-27 1958-12-02 Kendon Electronics Inc Masking devices for color television screen or the like
US3653900A (en) * 1969-08-15 1972-04-04 Zenith Radio Corp Selective etching process for changing shadow-mask aperture size
US3772555A (en) * 1972-03-30 1973-11-13 Gte Sylvania Inc Color cathode ray tube of the shadow mask variety

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4162421A (en) * 1975-03-19 1979-07-24 Rca Corporation Cathode ray tube having corrugated shadow mask with slits
FR2366687A1 (fr) * 1976-10-04 1978-04-28 Rca Corp Tube a rayons cathodiques du type a masque d'ombre
US4122368A (en) * 1977-07-08 1978-10-24 Rca Corporation Cathode ray tube with a corrugated mask having a corrugated skirt
US4146816A (en) * 1977-07-08 1979-03-27 Rca Corporation Cathode-ray tube with a corrugated mask having a corrugated hinging skirt
FR2425718A1 (fr) * 1978-05-11 1979-12-07 Rca Corp Tube a rayons cathodiques comportant un masque d'ombre a forme d'onde variable
US4280077A (en) * 1978-05-11 1981-07-21 Rca Corporation Cathode-ray tube having corrugated shadow mask with varying waveform
US4766341A (en) * 1985-09-18 1988-08-23 Mitsubishi Denki Kabushiki Kaisha Color picture tube with shadow mask having alternately displaced apertures
US5384511A (en) * 1991-09-19 1995-01-24 Mitsubishi Denki Kabushiki Kaisha Varible-thickness shadow mask for color cathode-ray tubes
US6043595A (en) * 1996-11-11 2000-03-28 Kabushiki Kaisha Toshiba Shadow mask having a curved surface with compressed, strengthening dents
US6294863B1 (en) * 1997-12-18 2001-09-25 Kabushiki Kaisha Toshiba Color cathode ray tube having a shadow mask with a plurality of strip shaped reinforcing beads
US6577047B2 (en) * 1999-12-21 2003-06-10 Matsushita Electric Industrial Co., Ltd. Cathode ray tube

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Publication number Publication date
JPS4965779A (nl) 1974-06-26
DE2353294A1 (de) 1974-05-09

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