EP0039906B1 - Aperture mask for a color television tube, color television tube comprising such a mask and method for obtaining the mask - Google Patents

Aperture mask for a color television tube, color television tube comprising such a mask and method for obtaining the mask Download PDF

Info

Publication number
EP0039906B1
EP0039906B1 EP19810103455 EP81103455A EP0039906B1 EP 0039906 B1 EP0039906 B1 EP 0039906B1 EP 19810103455 EP19810103455 EP 19810103455 EP 81103455 A EP81103455 A EP 81103455A EP 0039906 B1 EP0039906 B1 EP 0039906B1
Authority
EP
European Patent Office
Prior art keywords
mask
recess
openings
line
aperture mask
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
Application number
EP19810103455
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0039906A3 (en
EP0039906A2 (en
Inventor
Roland Thoms
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.)
BMC Industries Inc
Original Assignee
BMC Industries Inc
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
Priority claimed from US06/148,683 external-priority patent/US4353948A/en
Application filed by BMC Industries Inc filed Critical BMC Industries Inc
Priority to AT81103455T priority Critical patent/ATE22367T1/de
Publication of EP0039906A2 publication Critical patent/EP0039906A2/en
Publication of EP0039906A3 publication Critical patent/EP0039906A3/en
Application granted granted Critical
Publication of EP0039906B1 publication Critical patent/EP0039906B1/en
Expired legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/02—Manufacture of electrodes or electrode systems
    • H01J9/14—Manufacture of electrodes or electrode systems of non-emitting electrodes
    • H01J9/142—Manufacture of electrodes or electrode systems of non-emitting electrodes of shadow-masks for colour television tubes
    • 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
    • H01J29/076—Shadow masks for colour television tubes characterised by the shape or distribution of beam-passing apertures

Definitions

  • This invention relates to television picture tubes and, more specifically, to television picture tubes having aperture masks with a plurality of line of sight openings.
  • GB-A-2 020 892 describes an aperture mask with line of sight openings whose dimensions are defined in one direction by edges on the first side of the mask and in a direction perpendicular to the first direction by edges on the second side of the mask.
  • An object of the invention is to improve the electron beam transmission through an aperture mask.
  • the electron transparency of the mask is influenced by the phenomenon of electron scattering owing to impingement of electrons against portions of the mask.
  • the problem to be solved by the invention consisted in finding out a structural configuration of the mask by virtue of which the electron transparency of the mask would improve at least in part by the effect of electron scattering owing to impingement of electrons against edge portions of the mask.
  • an aperture mask (10, 48) for a television tube with line of sight openings having a rectangular shape, each opening being formed by a recess on a first side (10A) of the mask, the depth (T - T1) of the recess (15) being almost equal to the thickness (T) of the mask, and a through opening extending from the bottom (17) of the recess to the second side (10B) of the mask characterized in that the transverse dimension of the line of sight openings is defined by the sidewalls (12, 12A) of the through openings and that at least portions (14, 16) of the sidewalls of the recess are sloped whereby the first side of the mask is undercut, the edge portions (14A, 16A) of the undercuts on the first side (10A) defining the longitudinal dimension of the rectangular line of sight openings.
  • the electrons impinging against the peculiar opposite edge portions formed in the aperture of the mask are scattered in a way contributing to the improvement of the passage of electrons through the aperture and which reach the phos- phore screen, thereby increasing the electronic transparency of the mask.
  • a color television tube comprising the aperture mask according to this invention is defined in claims 4 and 5, while the method for obtaining the aperture mask of this invention is defined in claims 6-8.
  • reference numeral 10 generally defines a portion of a television aperture mask having a cone side surface 10A and a grade side surface 10B.
  • Surface 10A is referred to as the cone side since the larger opening or recess 15 is located therein and surface 10B is referred to as the grade side.
  • the grade side faces the electron guns while the cone side faces the television picture tube. This type of positioning provides the best pictures for conventional etched masks.
  • Located in aperture mask 10 is a line of sight opening which has edges that are defined by the top surface 10A and the bottom surface 10B of aperture mask 10.
  • a recess 15 which is defined in the bottom surface 10A by pair of side edges 11 and 11A and a pair of end edges 14A and 16A which are all located in the plane of the surface 10A of aperture mask 10.
  • Side edges 11 and 11A connect to end edges 14A and 16A to form a closed boundary in the plane of the surface 10A.
  • edges 11, 11A and edges 14A and 16A define the junction of the side walls of recess 15 with the surface 10A.
  • the side walls of recess 15 include a sloped or undercut surface 14 and a sloped or undercut surface 16 which respectively connect to edge 14A and edge 16A.
  • Surfaces 14 and 16 are undercut downward from the side 10A and radially outward from edges 14A and 16A toward the side 10B.
  • the thickness of aperture mask 10 is denoted by T which usually ranges from 0.1 to 0.2 mm (.004" to .008").
  • the length of undercut is denoted by A.
  • the undercut angle is denoted by ⁇ and the thickness of the remaining material that forms the bottom of recess 15 is denoted by T, with T 1 being substantially less than the thickness T of aperture mask 10, so that the depth (T - T 1 ) of the recess 15 is almost equal to the thickness T of the mask.
  • the bottom view shows the outline of an elongated slot in the bottom surface 10B which is defined by edge 12A, edge 12, edge 12B and edge 12C which are all located in the plane of the surface 10B.
  • Edges 12 and 12A are straight whereas edges 12B and 12C are curved.
  • the portion of the opening to the outside of lines X-X defines the portion of the opening which contains curved edges 12B and 12C.
  • the rectangular line of sight opening through aperture mask 10 is formed by edges 14A and 16A the distance between which define the longitudinal dimension of the opening and edges 12A and 12 the distance between which defines the transverse dimension of the line of sight openings. Note, in the bottom view (Fig. 3) the length of edge 12 and edge 12A also define the longitudinal opening; and the visible portions of edges 14A and 16A define the transverse portion of the line of sight opening. Although the bottom side view of aperture mask 10 is different from the top side view of aperture mask 10, the line of sight opening through aperture mask 10 is the same.
  • lines X-X which are located on both ends of the elongated slot, denote the separation point between the curvature of edges 12B and 12C and straight sections 12A and 12.
  • lines X-X are located to the outside of edges 14A and 16A to thereby insure the line of sight opening in aperture mask 10 is comprised of a set of straight edges with substantially square corners.
  • the curved ends are typical of cutting operations such as chemical etching.
  • bottom side surface 10B reveals an elongated opening therein which is substantially longer than the line of sight opening through the article
  • the process of etching permits one to etch a recess 15 in aperture mask 10.
  • the etching process is continued until it produces a recess 15 with undercut surfaces 14 and 16.
  • the size and shape of undercut surface can be controlled by the amount of etchant and time of etching and is generally within the skill of those in the art.
  • the elongated opening is etched from the opposite side. If desired, the elongated opening can be formed during the etching of the recess by simultaneously spraying etchant on opposite surface 10A and 10B. After etching, the elongated slot appears with radiused corners as shown in Fig. 3. In the process of forming the line of sight opening through the article, the etching continues until the etchant penetrates through the material of thickness T 1 . After penetration, the etchant is removed typically leaving an elongated opening such as defined by edges 12A, 12B, 12C and 12D. Lines X-X denote the radius portion of elongated opening which results from the etching action.
  • FIG. 3 An inspection of Fig. 3 shows the radius portion 12B and 12C project onto surfaces 15 and 16.
  • the radiused corners 12B and 12C of aperture mask 10 do not form a part of the line of sight opening in aperture mask 10. While the article and method have been described with respect to rectangular openings, it is apparent the process can be used to make other unusually shaped line of sight openings which are difficult or impossible to make with conventional techniques.
  • a conventional television aperture mask was etched having elongated slots with parallel sides and rounded ends.
  • the dimensions of the slot were as follows:
  • the measured light transmission through the slot was measured as 17.7 units.
  • a second aperture mask was made in accordance with the present invention in which the outline of the line of sight opening had a substantially rectangular configuration in accordance with Figs. 1, 2 and 3.
  • the dimension of the rectangular line of sight opening were as follows:
  • the transmission through the opening was measured as 18.36 units or an increase of approximately 4 percent in light transmission.
  • the transmission through the opening was measured as 18.36 units or an increase of approximately 4 percent in light transmission.
  • the second mask since the dimensions of the two holes were not exactly equal, a compensation for the area revealed that the second mask actually has an approximately 6.5 percent greater light transmission capability.
  • reference numeral 30 generally designates a cross sectional view of a television picture tube using the line of sight aperture mask of the present invention.
  • the television picture tube comprises a glass enclosure 31 having a base 32 and prongs 33 thereon for attachment to the electronics of the television set.
  • a focusing coil 35 that focuses the electron beam so the electron beams converge as they pass through openings 47 in aperture mask 48.
  • a deflection coil 37 which sweeps the electron beam across aperture mask 48.
  • the aperture mask 48 is located with a plurality of elongated openings 47 located therein.
  • a phosphor strip 40 Located immediately behind elongated slots 47 is a phosphor strip 40. Although three phosphor strips are located behind each opening in the cross sectional view only one strip is visible in the cross sectional view. The phosphor strips comprise the primary colors red, blue and green which, when excited by the electrons, produce the proper color on face plate 39 of television picture tube 30.
  • Figs. 5 and 6 respectively show a top view of a portion of the television aperture mask and a television picture tube and a side view of a television picture tube.
  • the front glass envelope portion of the television picture tube is designated by reference numeral 39 with reference numerals 40, 41 and 42 designating the red, blue and green phosphor stripes which extend longitudinally parallel to the elongated openings which are located in aperture mask 48.
  • Fig. 7 shows schematically the slot arrangement of a typical aperture mask having a series of elongated slots. Located between phosphor stripes 40, 41 and 42 is a suitable black light-absorbing medium that does not emit any color should it be struck by electrons.
  • the aperture mask is denoted by reference numeral 48 and with cone side 45 facing the electron gun and the grade side 46 facing the phosphor stripes which are located on face plate 34. Since the most metal is removed from side 45 to provide recess 45A, this side is denoted as the cone side and in the embodiment shown is located facing the electron gun. Typical prior art aperture masks the cone side was located facing the phosphor side.
  • Fig. 5 reveals how the grade side edge surfaces 53 and 54 limit the electrons in the lateral direction.
  • Fig. 6 shows a side view of aperture mask 48 with reference numeral 39 denoting the face plate and reference numeral 40 indicating a phosphor stripe.
  • the aperture masks 48 has an opening 45A on the cone side 45 and an elongated opening on the opposite side.
  • the tie bar or bridges as they refer to in the prior art are located with the narrow end of the bridge or tie bar facing the phosphor stripe 40 and the tie bar extending from the cone side 45 to grade side 46.
  • Fig. 6 shows tie bar 50 to comprise a grade side surface 50B, a cone side surface 50A and an interior surface 51 on lower tie bar and an upper interior surface 52 on upper tie bar 50.
  • the upper and lower boundaries of the line of sight opening in aperture mask 48 is defined by the junction of surface 52 with cone side surface 44 and junction of surface 51 with cone side surface 45.
  • the plurality of tie bars located in the spaced relationship provide for accurate defining of an opening for the excitation of the phosphor stripes located along the televison picture tube.
  • the aperture masks have the cone side facing the electron gun, one should have the bottom of the recess region, which is located adjacent the sides of the line of sight openings, sufficiently flat or angled so that the electron beams that impinge on the bottom of the recess region do not deflect through the line of sight opening in the aperture mask.
  • the bottom of the recess region is parallel to the mask cone side surface, one does not obtain scattering electron reflections through the line of sight openings.
  • the portion of the recess side walls which do not define a portion of the line of sight opening should be set sufficiently far back from the line of sight opening in the aperture mask so that the path of the electron beam is not obstructed by the recess region side walls or the cone side surface of the aperture mask. In conventional mounting with the grade side toward the electron gun, these adjustments would not be necessary.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Electrodes For Cathode-Ray Tubes (AREA)
  • ing And Chemical Polishing (AREA)
EP19810103455 1980-05-12 1981-05-07 Aperture mask for a color television tube, color television tube comprising such a mask and method for obtaining the mask Expired EP0039906B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT81103455T ATE22367T1 (de) 1980-05-12 1981-05-07 Schattenmaske fuer eine farbfernsehroehre, farbfernsehroehre mit einer solchen maske und verfahren zum herstellen der maske.

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US14868280A 1980-05-12 1980-05-12
US148683 1980-05-12
US06/148,683 US4353948A (en) 1980-05-12 1980-05-12 Hole technology
US148682 1980-05-12

Publications (3)

Publication Number Publication Date
EP0039906A2 EP0039906A2 (en) 1981-11-18
EP0039906A3 EP0039906A3 (en) 1982-06-16
EP0039906B1 true EP0039906B1 (en) 1986-09-17

Family

ID=26846063

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19810103455 Expired EP0039906B1 (en) 1980-05-12 1981-05-07 Aperture mask for a color television tube, color television tube comprising such a mask and method for obtaining the mask

Country Status (6)

Country Link
EP (1) EP0039906B1 (pt)
JP (1) JPH0713158Y2 (pt)
AR (1) AR223591A1 (pt)
BR (1) BR8102909A (pt)
CA (1) CA1175876A (pt)
DE (1) DE3175329D1 (pt)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE69126695T2 (de) * 1990-11-22 1998-02-12 Toshiba Kawasaki Kk Schattenmaske für Farbkathodenstrahlröhre

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4881762U (pt) * 1971-12-30 1973-10-05
US3973965A (en) * 1972-05-30 1976-08-10 Tokyo Shibaura Electric Co., Ltd. Making shadow mask with slit-shaped apertures for CRT
US4069085A (en) * 1973-07-16 1978-01-17 U.S. Philips Corporation Apparatus for forming apertures in a thin metal tape such as a shadow mask for a color television display tube
US3916243A (en) * 1974-09-20 1975-10-28 Buckbee Mears Co Channeled shadow mask
JPS5310961A (en) * 1976-07-19 1978-01-31 Hitachi Ltd Color picture tube
GB2020892A (en) * 1978-05-10 1979-11-21 Rca Corp C.R.T. Silt Type Shadow Mask
US4293792A (en) * 1979-12-18 1981-10-06 Rca Corporation Color picture tube having improved slit type shadow mask

Also Published As

Publication number Publication date
EP0039906A3 (en) 1982-06-16
AR223591A1 (es) 1981-08-31
BR8102909A (pt) 1982-02-02
EP0039906A2 (en) 1981-11-18
JPH069043U (ja) 1994-02-04
DE3175329D1 (en) 1986-10-23
CA1175876A (en) 1984-10-09
JPH0713158Y2 (ja) 1995-03-29

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