EP1432003A1 - Tube cathodique comprenant un masque d'ombre avec une partie peripherique intermediaire et une jupe peripherique partiellement corrode - Google Patents

Tube cathodique comprenant un masque d'ombre avec une partie peripherique intermediaire et une jupe peripherique partiellement corrode Download PDF

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Publication number
EP1432003A1
EP1432003A1 EP02028679A EP02028679A EP1432003A1 EP 1432003 A1 EP1432003 A1 EP 1432003A1 EP 02028679 A EP02028679 A EP 02028679A EP 02028679 A EP02028679 A EP 02028679A EP 1432003 A1 EP1432003 A1 EP 1432003A1
Authority
EP
European Patent Office
Prior art keywords
skirt
border
shadow mask
mask
cavities
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.)
Withdrawn
Application number
EP02028679A
Other languages
German (de)
English (en)
Inventor
Louis-Emmanuel Matalon
Pedro-Eugenio Cosma
Kelly Eugene Hamm
George Van Cleve
Original Assignee
Thomson Licensing SAS
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 Thomson Licensing SAS filed Critical Thomson Licensing SAS
Priority to EP02028679A priority Critical patent/EP1432003A1/fr
Publication of EP1432003A1 publication Critical patent/EP1432003A1/fr
Withdrawn legal-status Critical Current

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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
    • H01J2229/00—Details of cathode ray tubes or electron beam tubes
    • H01J2229/07—Shadow masks
    • H01J2229/0727—Aperture plate
    • H01J2229/0766—Details of skirt or border
    • H01J2229/0772—Apertures, cut-outs, depressions, or the like

Definitions

  • the invention relates to a color cathode ray tube (CRT) of the type having a shadow mask mounted in spaced relation to a luminescent screen and, more particularly to a border and skirt of the shadow mask.
  • CTR color cathode ray tube
  • a color cathode ray tube typically has an electron gun, an aperture mask and a screen.
  • the screen is located on an inner surface of the faceplate of the CRT tube.
  • the screen may be a luminescent screen.
  • Luminescent screens typically comprise an array of three different color-emitting phosphors (e.g., green, blue and red) formed thereon. Each of the color-emitting phosphors is separated from another by matrix.
  • the matrix is typically formed of a light absorbing black, inert material.
  • the aperture mask also referred to as a shadow mask, is interposed between the electron gun and the screen.
  • the shadow mask comprises a multi-aperture thin sheet of metal, such as steel, that is contoured to approximately parallel the inner surface of the CRT tube faceplate.
  • the shadow mask functions to direct electron beams generated in the electron gun toward appropriate color-emitting phosphors on the screen of the CRT tube.
  • Deviation of the mask apertures during tube processing or during tube operation may undesirably misdirect the electron beams directed therethrough.
  • the effect of the misdirection is a misalignment of the electron beam centers with the centers on their intended matrix openings.
  • local light output global light output and color purity can be degraded. In severe cases where electron beams excite unintended color-emitting phosphors, a large deterioration in color purity can be observed.
  • the present invention relates to a shadow mask for use in a color cathode ray tube (CRT).
  • the shadow mask comprises a multi-aperture masking portion surrounded by a border, which is, in turn, surrounded by a skirt.
  • the multi-aperture masking portion may include an array of apertures as well as a partially etched continuation of the aperture array such as an Extended Large Side Array (ELSA).
  • ELSA Extended Large Side Array
  • the demarcation between the border and the skirt is preferably at the bend line of the mask.
  • the skirt is substantially perpendicular to the multi-aperture masking portion as well as the border.
  • the border and skirt are partially etched across portions of one or more sides thereof.
  • an outer, screen-facing, surface of the border has a plurality of cavities formed therein. The plurality of cavities extends around the bend line and continues a predetermined distance down the skirt. As a result, contour control of the shadow mask is improved.
  • FIG. 1 is a plan view, partially in axial section, of a color cathode ray tube (CRT) made according to embodiments of the present invention
  • FIG. 2 is a plan view of the shadow mask assembly of the CRT of FIG. 1;
  • FIG. 3A-3B are enlarged fragmentary views of the multi-aperture masking portion of the shadow mask shown in FIGS. 1 and 2 illustrating two different aperture patterns;
  • FIG. 4 is an enlarged fragmentary view of the multi-aperture masking portion of the shadow mask shown in FIGS. 1 and 2 illustrating the aperture cross-section configuration
  • FIG. 5A is a top view of one quadrant of the flat shadow mask shown in FIGS. 1 and 2 before the mask is shaped;
  • FIG. 5B is a cross-sectional view of the formed mask including the multi-aperture masking portion, a partially etched border and a partially etched skirt;
  • FIGS. 6A-6B are top and cross-sectional views of cavities formed in a screen-facing portion of the border and skirt.
  • FIGS. 7A-7B are top and cross-sectional views of cavities formed in a gun-facing portion of the skirt.
  • FIG. 1 shows a conventional color cathode ray tube (CRT) 20 having a glass envelope 21 comprising a faceplate panel 22 and a tubular neck 24 connected by a funnel 23.
  • a three-color luminescent phosphor screen 25 is carried on the inner surface of the faceplate panel 22.
  • the screen 25 is a line screen (although disclosure is not limited to a line screen structure), which includes a multiplicity of screen elements (not shown) comprised of red-emitting, green-emitting and blue-emitting phosphor stripes R, G, and B, respectively, arranged in triads, each triad including a phosphor line of each of the three colors.
  • the R, G, and B phosphor stripes extend in a direction that is generally normal to the plane in which the electron beams are generated.
  • a light-absorbing matrix (not shown) separates each of the phosphor stripes.
  • a thin conductive layer (not shown), preferably of aluminum, overlies the screen 25 and provides means for applying a uniform first anode potential to the screen 25, as well as for reflecting light, emitted from the phosphor elements, through the viewing surface thereof.
  • the screen 25 and the overlying aluminum layer (not shown) comprise a screen assembly.
  • a multi-aperture color selection electrode, or shadow mask assembly 26 is removably mounted, by conventional means, within the faceplate panel 22, in a predetermined spaced relation to the screen 25.
  • An electron gun 27, shown schematically by the dashed lines in FIG. 1, is positioned in the neck 24 to generate three electron beams through the shadow mask assembly 26 to the screen 25.
  • the shadow mask assembly 26, shown in FIGS. 1 and 2 is of a generally rectangular configuration and includes a mask 31 comprising a multi-aperture masking portion 28 surrounded by a border 41 and a skirt 32.
  • the mask 31 is attached to a peripheral frame member 29 (FIG. 1) along a peripheral portion of the skirt 32.
  • the masking portion 28 is formed with a convex outer surface 33 (FIG. 1) and a concave inner surface 34 (FIG. 1) with an array of apertures 36 therethrough.
  • the apertures in the masking portion 28 may comprise for example, slots as shown in FIG. 3A as well round-shaped openings as shown in FIG. 3B, among others.
  • the mask 31 is formed of a conducting material, such as, for example, steel, or Invar, among others, having a thickness of about 0.18 mm (millimeters) to about 0.30 mm.
  • the mask 31 is attached to the peripheral frame member 29 along portions of the skirt portion 32 by welds 37.
  • the mask is welded to the inner surfaces of the frame using a mask in frame assembly (MIFA) configuration.
  • MIFA mask in frame assembly
  • the welds 37 are positioned to fall within the overlapping area of the skirt portion 32 and the peripheral frame member 29 and are preferably within about 3 mm from the edge of the skirt portion 32.
  • the thickness of the skirt portion should preferably be about the same as that of the masking portion.
  • a cross-sectional view of each of the apertures 36 (such as the types shown in FIGS. 3A-3B) formed in the masking portion may have an intersecting cavity shape having a large cavity 38 formed in the convex outer surface 33 of the masking portion 28 and a small cavity 39 formed in the concave inner surface 34 of the masking portion 28.
  • the two cavities 38, 39 intersect at a knife-edge 40, which determines the size of the apertures 36.
  • the mask 31 thickness is shown by the dimension T, while the depth of the large cavity 38 is shown by the dimension t.
  • the aperture to aperture spacing is shown by dimension a.
  • the large cavities 38 may extend through the masking portion 28, negating the need for small cavities 39.
  • the multi-aperture masking portion is formed by sequentially coating each side of the mask 31 with a photoresist material.
  • the photoresist material is exposed to light and developed to define the aperture pattern therein to the surface of the mask 31.
  • the mask 31 is etched to form the apertures 36 therethrough.
  • the border 41 and skirt 32 of the mask 31 may be partially etched across portions of one or more sides thereof, as shown in FIGS. 5A-5B.
  • FIG. 5A a top view of one quadrant of mask 31 including the aperture masking portion 28 and the partially etched border 41 and skirt 32 are shown.
  • the demarcation between the border 41 and skirt 32 is the bend line 60.
  • the convex outer surface of the border 141 and a portion of the outer surface of the skirt 132 preferably have cavities 136a formed therein.
  • a portion of the inner surface of the skirt 232, located down the skirt away from the cavities 136a may have cavities 136b formed therein.
  • the cavities 136a extend about 2-3 mm down the outer surface of the skirt 132 past the bend line 60.
  • the cavities 136a in the outer surface of the border 141 may be separated from the masking portion 28 by a transition region 140, which may or may not have cavities formed therein.
  • the cavities 136b may be separated from the cavities 136a on the skirt by a transition region 145, which may or may not also be free of cavities.
  • the skirt regions containing cavities 136a and 136b may be coincidental. However, the cavities 136a and 136b should preferably not intersect so as to form perforations in the skirt 32.
  • the cavities 136a may have any shaped opening including, for example, round, hexagonal, triangular or rectangular, among others.
  • the sidewalls may be for example, cup-shaped or substantially perpendicular to the surfaces of the border 41 and the skirt 32.
  • the mask 31 thickness is shown by the dimension T, while the depth of the cavities 136a is shown by the dimension t.
  • the cavities 136a describe a general hexagonal pattern having a spacing "a" between the apertures and a 60° included angle between the rows of apertures, as shown in FIG. 6A.
  • the cavities 136a may have diameters of about 0.335 mm to about 0.365 mm.
  • the center-to-center spacing "a" (FIG. 6A) of the cavities 136a may be about 0.460 mm.
  • the cavities may have a depth of about 0.160 mm.
  • the cavities 136a may be formed by coating the mask 31 with a photoresist material.
  • the photoresist material is exposed to light and developed to define the cavity pattern therein on the outer surface of the border 141 and the skirt 132.
  • the mask 31 is etched to form the cavities 136a therein.
  • the cavities 136b may have any shape opening including, for example, round, hexagonal, triangular or rectangular, among others.
  • the sidewalls may be cup-shaped or substantially perpendicular to the surface of the border 41.
  • the mask 31 thickness is shown by the dimension T, while the depth of the cavities 136b is shown by the dimension t.
  • the cavities 136b describe a general hexagonal pattern having a spacing "a" between the apertures and a 60° included angle between the rows of apertures, as shown in FIG. 7A.
  • the cavities 136b formed in the inner surface of the skirt 232 may have diameters of about 0.485 mm to about 0.455 mm.
  • the center-to-center spacing "a" (FIG. 7A) of the cavities 136b may be about 0.620 mm.
  • the cavities may have a depth of about 0.160 mm.
  • the cavities 136b are formed by coating the mask 31 with a photoresist material.
  • the photoresist material is exposed to light and developed to define the cavity pattern therein on the inner surface of the skirt 232.
  • the mask 31 is etched to form the cavities 136b therein.
  • cavities 136a on the border outer surface 141 and at least a portion (2-3mm) of the skirt outer surface 132 improves the control of the formed contour of the masking portion 28 of the mask 31 during the process of forming the mask 31.
  • the presence of cavities 136a in these regions also reduces the formed flare of the skirt 32, thereby facilitating insertion of the mask 31 into the frame 29 during CRT fabrication where the mask 31 is welded inside the frame 29 (MIFA).
  • MIFA welded inside the frame 29
  • the reduced flare of the skirt 32 improves the fit of the mask 31 to the frame 29 for the placement of welds 37.
  • the presence of the cavities 136a on the outer border surface 141 also aids removal of the formed mask 31 from the mask forming punch during the mask forming procedure.
  • cavities 136a on the outer surface of the skirt 132 and/or the presence of cavities 136b on the inner surface of the skirt 232 reduce the stiffness of the skirt 32 thereby reducing the transmission of motion from the skirt 32 into the contour of masking portion 28. Reducing the stiffness is useful to minimize disturbance of the masking portion 28 when there is differential thermal expansion between the mask 31 and the frame 29.
  • cavities 136b on the lower portion of the inner surface of the skirt 232 rather than on the outer surface reduces mask-forming die wear during the mask forming procedure. Also, the presence of cavities 136b on the lower portion of the inner surface of the skirt 232 rather than the outer surface also avoids the creation of fluid-entrapping volumes undesirably created by the juxtaposition of cavities 136a and the inside surface of the frame 29 for a MIFA arrangement. Such fluid entrapment. may retard the drying of the mask assembly 26 following a mask assembly wash operation during CRT fabrication processes.

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  • Electrodes For Cathode-Ray Tubes (AREA)
EP02028679A 2002-12-20 2002-12-20 Tube cathodique comprenant un masque d'ombre avec une partie peripherique intermediaire et une jupe peripherique partiellement corrode Withdrawn EP1432003A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP02028679A EP1432003A1 (fr) 2002-12-20 2002-12-20 Tube cathodique comprenant un masque d'ombre avec une partie peripherique intermediaire et une jupe peripherique partiellement corrode

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP02028679A EP1432003A1 (fr) 2002-12-20 2002-12-20 Tube cathodique comprenant un masque d'ombre avec une partie peripherique intermediaire et une jupe peripherique partiellement corrode

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EP1432003A1 true EP1432003A1 (fr) 2004-06-23

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Citations (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3862448A (en) * 1971-09-03 1975-01-21 Hitachi Ltd Colour picture tube including shadow mask having self-compensation function for thermal stress
US4191909A (en) * 1978-10-23 1980-03-04 Zenith Radio Corporation Color CRT with shadow mask having peripherally grooved skirt
JPS5673846A (en) * 1979-11-21 1981-06-18 Hitachi Ltd Color picture tube
JPS57202626A (en) * 1981-06-08 1982-12-11 Mitsubishi Electric Corp Shadow mask
JPS5842144A (ja) * 1981-09-08 1983-03-11 Toshiba Corp カラ−受像管
JPS58197636A (ja) * 1982-05-10 1983-11-17 Mitsubishi Electric Corp シヤドウマスク
JPS6065431A (ja) * 1983-09-20 1985-04-15 Nec Corp カラ−ブラウン管用シャドウマスク
JPS60232640A (ja) * 1984-04-28 1985-11-19 Dainippon Printing Co Ltd シヤドウマスク
FR2576452A1 (fr) * 1985-01-22 1986-07-25 Rca Corp Tube image couleur a masque d'ombre perfectionne
US4859901A (en) * 1981-10-29 1989-08-22 U.S. Philips Corporation Color CRT shadow mask with wrinkle-free corners
JPH0447649A (ja) * 1990-06-13 1992-02-17 Nec Kansai Ltd 陰極線管
JPH08298078A (ja) * 1995-04-28 1996-11-12 Toshiba Corp カラー受像管
JPH09320481A (ja) * 1996-05-30 1997-12-12 Nec Kansai Ltd カラー陰極線管用シャドウマスク
JPH11120932A (ja) * 1997-10-09 1999-04-30 Matsushita Electron Corp カラー陰極線管
EP0924741A1 (fr) * 1997-03-14 1999-06-23 Kabushiki Kaisha Toshiba Tube cathodique couleur
EP1117119A2 (fr) * 2000-01-11 2001-07-18 Hitachi, Ltd. Tube couleur à rayons cathodiques
US20020113538A1 (en) * 2000-12-22 2002-08-22 Lg Electronics Inc. Color cathode-ray tube

Patent Citations (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3862448A (en) * 1971-09-03 1975-01-21 Hitachi Ltd Colour picture tube including shadow mask having self-compensation function for thermal stress
US4191909A (en) * 1978-10-23 1980-03-04 Zenith Radio Corporation Color CRT with shadow mask having peripherally grooved skirt
JPS5673846A (en) * 1979-11-21 1981-06-18 Hitachi Ltd Color picture tube
JPS57202626A (en) * 1981-06-08 1982-12-11 Mitsubishi Electric Corp Shadow mask
JPS5842144A (ja) * 1981-09-08 1983-03-11 Toshiba Corp カラ−受像管
US4859901A (en) * 1981-10-29 1989-08-22 U.S. Philips Corporation Color CRT shadow mask with wrinkle-free corners
JPS58197636A (ja) * 1982-05-10 1983-11-17 Mitsubishi Electric Corp シヤドウマスク
JPS6065431A (ja) * 1983-09-20 1985-04-15 Nec Corp カラ−ブラウン管用シャドウマスク
JPS60232640A (ja) * 1984-04-28 1985-11-19 Dainippon Printing Co Ltd シヤドウマスク
FR2576452A1 (fr) * 1985-01-22 1986-07-25 Rca Corp Tube image couleur a masque d'ombre perfectionne
JPH0447649A (ja) * 1990-06-13 1992-02-17 Nec Kansai Ltd 陰極線管
JPH08298078A (ja) * 1995-04-28 1996-11-12 Toshiba Corp カラー受像管
JPH09320481A (ja) * 1996-05-30 1997-12-12 Nec Kansai Ltd カラー陰極線管用シャドウマスク
EP0924741A1 (fr) * 1997-03-14 1999-06-23 Kabushiki Kaisha Toshiba Tube cathodique couleur
JPH11120932A (ja) * 1997-10-09 1999-04-30 Matsushita Electron Corp カラー陰極線管
EP1117119A2 (fr) * 2000-01-11 2001-07-18 Hitachi, Ltd. Tube couleur à rayons cathodiques
US20020113538A1 (en) * 2000-12-22 2002-08-22 Lg Electronics Inc. Color cathode-ray tube

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