US3380354A - Light source for shadow mask tubes - Google Patents

Light source for shadow mask tubes Download PDF

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Publication number
US3380354A
US3380354A US513033A US51303365A US3380354A US 3380354 A US3380354 A US 3380354A US 513033 A US513033 A US 513033A US 51303365 A US51303365 A US 51303365A US 3380354 A US3380354 A US 3380354A
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United States
Prior art keywords
light source
light
lens
light rays
tube
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Expired - Lifetime
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US513033A
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English (en)
Inventor
Thornton Douglas
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National Video Corp
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National Video Corp
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Publication date
Application filed by National Video Corp filed Critical National Video Corp
Priority to US513033A priority Critical patent/US3380354A/en
Priority to GB53166/66A priority patent/GB1159818A/en
Priority to NL6616697A priority patent/NL6616697A/xx
Priority to DE19661462871 priority patent/DE1462871B2/de
Priority to FR86780A priority patent/FR1504229A/fr
Application granted granted Critical
Publication of US3380354A publication Critical patent/US3380354A/en
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00Apparatus 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
    • H01J9/20Manufacture of screens on or from which an image or pattern is formed, picked up, converted or stored; Applying coatings to the vessel
    • H01J9/22Applying luminescent coatings
    • H01J9/227Applying luminescent coatings with luminescent material discontinuously arranged, e.g. in dots or lines
    • H01J9/2271Applying luminescent coatings with luminescent material discontinuously arranged, e.g. in dots or lines by photographic processes
    • H01J9/2272Devices for carrying out the processes, e.g. light houses
    • H01J9/2274Light sources particularly adapted therefor

Definitions

  • the instant invention relates to color television and more particularly to a novel light source employed in a lighthouse apparatus used to form phosphor dot patterns in color tubes of the shadow-mask variety.
  • Shadow mask tubes are well known in the color television receiver art and are typically comprised of at least one electron beam source and a multi-apertured shadow mask which is positioned adjacent the tube face. Deflection means are provided to deflect the electron beam, horizontally and vertically to trace out a raster.
  • the tube face is provided with a plurality of phosphor dots of each of the three primary colors.
  • the geometry of the electron beam, shadow mask and phosphor dot pattern is so arranged as to cause each of the electron beams to strike phosphor dots of only one associated primary color to the exclusion of the remaining colors.
  • the phosphor dot pattern is conventionally formed upon the face of the tube by forming a slurry containing phosphor material of one primary color, a photosensitive binder and an adhesive material; uniformly applying the slurry upon the tube face; and passing light rays through the multi apertured shadow mask.
  • the exposed portions of slurry harden and adhere tightly to the glass surface due to the presence of the photosensitive binder.
  • the tube face then undergoes a washing process which removes the unexposed portions of slurry.
  • the exposed portions remaining are substantially in the form of dots due to the circular-shaped apertures in the shadow-mask which the light rays pass through.
  • a light source for example, a mercury arc lamp, which has its light rays directed upon a tapered transparent member, such as, for example, a quartz member so as to simulate a point light source.
  • the radiation pattern for such light source is substantially circular, and hence, the intensity of the light greatly diminishes for rays in the vicinity of the edges of the tube face. It is, therefore, extremely important to provide a light source which has a superior radiation pattern so that the light rays impinging upon the tube face in the region of the edges of the tube face will have an intensity which is greater than the intensity of light rays directed toward central region of the tube face. This requirement is a result of the shadow mask apertures which are smaller in diameter in the region of the edges.
  • the instant invention is comprised of a high intensity light source which is located within a substantially closed housing.
  • the lower half of the housing is a substantially dome-shaped highly-polished reflective surface, arranged to reflect light rays so that substantially all of the light rays will be directed toward the region of an opening provided toward the upper end of the housing.
  • the reflector portion has a substantially ellipticalshaped surface, which configuration is chosen as to appropriately deflect the light rays toward the opening provided at the upper end of the housing.
  • a lens is mounted within the housing opening and has a configuration and index of refraction so as to deflect the light rays impinging upon the lens to pass through the lens and the housing opening so as to form a radiation pattern having a configuration of a cardioid (i.e. heartshaped).
  • the objective of the lens is to deflect light rays, which should all impinge upon a single focal point within the lens, to an angle of no greater than 45 relative to the color tube longitudinal axis.
  • the lamp structures presently available deviate somewhat from the ideal point light source condition.
  • the design of the instant invention was chosen to cause the light rays to fall upon a locus curve contained within the design of the lens such as to deflect the maximum number of light rays by no more than a 45 angle from the longitudinal axis for illuminating the tube face so as to obtain an extremely enhanced radiation and to fully compensate for imperfections in the light source.
  • Another object of the instant invention is to provide a novel light source for use in a lighthouse structure employed to form phosphor dot patterns upon tube faces of shadow-mask color tubes.
  • Another object of the instant invention is to provide a light source for use in lighthouse structures and the like wherein the light rays emanating from the lighthouse have a cardioidic intensity pattern.
  • Another object of the instant invention is to provide a novel light source for use in forming the phosphor dot pattern in color tubes of the shadow-mask type, wherein the intensity of light rays impinge upon the regions of the tube face near the edges thereof are greatly enhanced in intensity.
  • FIGURE 1 is an elevated sectional view of a prior art lighthouse apparatus employing a conventional light source.
  • FIGURE 2 is an elevational view of the light source apparatus of the instant invention.
  • FIGURE 2a is a crosssectional view of an ideal lens for use in the light source apparatus of FIGURE 2.
  • FIGURES 3m and 3b are cross-sectional views of the lens of FIGURE 2 employed in the arrangement of the instant invention.
  • FIGURE 4 shows a cross-sectional view of a preferred embodiment of the lens employed in the light source apparatus of FIGURE 2.
  • FIGURE 4w is a perspective view of the lens of FIG- URE 4.
  • FIGURES 5a and 5b show radiation patterns in the vertical and horizontal planes for the light source of FIGURE 1.
  • FIGURES 6a: and 6b show radiation patterns in the vertical and horizontal planes for the light source of the instant invention.
  • FIG. 1 shows a sectional view of a lighthouse apparatus 10 employed for the purpose of forming a phosphor dot pattern in the three primary colors upon the screen 13a of the shadow-mask tube face 13.
  • the cylindrical wall 11 of the color tube is mounted upon the housing 12 of lighthouse apparatus 10.
  • the cylindrical side wall 11 positions and supports the face plate screen 13 of the tube as well as the shadowmask structure 14, which is provided with a plurality of apertures 14a therethrough.
  • the color tube portion comprising the cylindrical side wall 11, the screen 13, and shadow-mask structure 14, is disassociated from the remainder of the color tube structure during the lighthouse operation.
  • the base or floor 12a of housing 12 supports a light source comprised of a housing 15, which is supported upon a turntable v16, mounted for rotation about shaft 17 for a reason to be more fully described.
  • Opening 15a supports a tapered light conduit 19 enclosed within secondary housing 20 so that the extreme end portion 19a of the tapered conduit protrudes through an opening in secondary housing 20.
  • the conduit consists of a material of high transparency to rays of the particular Wave lengths employed.
  • the light rays 21 from point light source 19 pass through a corrective system 22 positioned upon a supporting structure 23 having a substantially large opening 24.
  • the corrective lens system 20 is provided for the purpose of deflecting the light rays in the manner shown by the upper light ray portions 21a to correct for the effects of radial misregister and dynamic conversion.
  • the corrective lens system 22 lends no novelty to the light source of the instant invention and it is suflicient, therefore, to understand that the lens 22 functions to compensate for the effects of radial misregister and dynamic convergence phenomena which occur in shadow-mask color tubes.
  • the lens 22 functions to compensate for the effects of radial misregister and dynamic convergence phenomena which occur in shadow-mask color tubes.
  • light rays 21 which intersect line 25 will all have equal magnitudes of light intensity along any arc such as, for example, the arc 25 with the center of the are being the tip of point light source 1911.
  • This radiation pattern being the case, it can clearly be seen that since the interior surface 13a of tube face 13 is relatively flat as compared to are 25, that light rays 2111 at the outer extreme face will be of significantly lower light intensity than the light rays striking in the central region of tube face 13a. This effect is increased when using a tube 90 or more deflection angle.
  • turntable 16 upon which the light source is mounted can be seen to position the light source, which lies along line 1% at an eccentric angle relative to the axis 17a of the shaft 17.
  • turntable 16 is provided with three slots 26 (only two of which are shown in FIG. 1) which are arranged at intervals around turntable 16. These slots 26 cooperate with a detent 27 which is spring loaded by device 28 for the purpose of locking turntable 16 into one of the three angular positions.
  • This turntable arrangement is provided for the purpose of locating the tip 19a of point light source 19 at the effective color center of one of the three electron beams provided in the shadow-mask color tube.
  • the interior face 13a of the color tube is coated with a phosphor material of one of the three primary colors.
  • the tube face and the shadow mask 13 and 14, respectively, are then positioned upon the lighthouse structure in the manner shown in FIG. 1, and the turntable is accurately located with the point light source occupying the same position as the electron beam occupies within the color tube for the particular phosphor material which has been deposited upon interior tube face 13a.
  • the tube face 13 is then removed from the lighthouse apparatus and undergoes a washing operation in which all unexposed areas of the phosphor material are washed away from the tube face.
  • the tube interior face 13a is coated with the second and third remaining phosphor colors and the light source turntable 16 is rotated to move the point light source 1901 to the positions occupied by the second and third remaining electron beams so as to complete the phosphor dot formation process.
  • the description "and mode of operation of the turntable 16 is set forth in detail in U.S. Patent No. 2,885,935, for example, and this turntable apparatus lends no novelty to the device of the instant invention.
  • the light source apparatus 30 of the instant invention is shown in FIG. 2 and may be substituted for the light source arrangement of the prior art shown in FIG. 1 by suitably being mounted upon turntable 16 or any other similar light source positioning apparatus.
  • the light source 3% of the instant invention is comprised of a substantially dome-shaped reflector member 31 which has an ellipticalshaped reflective surface portion 32, which surface has been rotated downwardly about the prime focus point 41 for a purpose to be more fully described.
  • a mercury arc lamp 40 is positioned along the longitudinal axis 42 of the light source apparatus 30, with the illuminating mercury arc being positioned at the prime focal point 41.
  • Suitable power source means (not shown) are connected to the electrodes 43 and 43a of lamp 40.
  • the upper housing portion 44 of the light source structure St ⁇ is secured to the reflector portion 3-1 by suitable fastening means 33 and is provided with an opening 50 for receiving the lens 45.
  • the mercury are located at prime focal point 41 of mercury arc lamp 40 emits light rays in substantially all directions. Considering the light rays reflected from the extreme edges of the reflective surface portion 32, it can be seen that the downward directed light ray 46 is reflected from the extreme lower point 32' of reflective surface 32, thereby assuming the light ray path 46a and striking a point lying on curve 45a in lens 45.
  • the substantially circular shaped curve 45a which is the focus locus of all light rays reflected by the reflector 31 results from the fact that the mercury arc lamp 40 is not an ideal point light source and, therefore, light rays cannot focus at the ideal focal point 48 in lens 45.
  • the assembly has therefore been designed to cause the light rays to focus on a locus curve 45a to compensate for imperfections in the light source.
  • Considering the upper extreme edge 32" of reflector surface 32 it can be seen that light ray 49 emitted from the light source strikes the reflector surface at 32" and assumes the path 49a, striking the locus curve 450.
  • a light ray 51 impinging upon the intermediate region of reflect-or surface 32 is deflected and assumes path 51a. This light my also has its focal point along the locus curve 45a.
  • the amount of deflection which the light rays experience is a function of the angle of incidence of the light ray upon the entry surface, the index of refraction of the lens, and the angle of incidence which the light ray makes at the exit surface of the lens.
  • the prime objective of the light source apparatus of the instant invention is to deflect the light rays in such a manner that the maximum number of light rays emitted from the light source will be emitted at no greater than a 45 angle, relative to the longitudinal axis 42, assuming the use of a 90 deflection ty-pe color tube.
  • the lens 45' shown in FIG. 2a has a curved entry surface 52 which closely approximates a pseudosphere or invert sphere. Entering light rays 55- are refracted by ideallens surface 52 so as to be emitted at the exit surface 53 at an angle of 45 relative to the light source longitudinal axis 42.
  • the light source is not an ideal point light source, this necessitates a modification in the configuration and design of the focusing lens, resulting in a lens 50 having the configuration shown in FIGS. 2 and 3a and 3b.
  • the lens material of fused quartz having an index of refraction n. equal to 1.48 for a wavelength of light equal to 3650 angstroms, it is desired to ascertain the angle which the entry surface 52 of lens 45 makes with the longitudinal axis 42.
  • the optimum entry surface forms an angle of l8- /z with the light source longitudinal axis 42. Having determined the optimum angle which the entry surface makes with the longitudinal axis 42, it is next desired to relate the design of the entry surface to the exit surface 56 (see FIG. 3a) so as to minimize the size of the outgoing bundle of light rays being emitted from the light source.
  • the objective is to locate the plane 56' of the exit surface 56 so that it intersects the smallest part or neck portion of the bundle of light rays 57. This may be done simply by plotting the light rays and selecting that portion of the bundle of light rays which is narrowest and this is a simple optical ray tracing problem.
  • the entry surface 52 of the lens 50 may be extended as shown by the dotted line 52 (see FIG. 4) so as to form a cone-shaped configuration.
  • the amount of vertical light i.e. light rays emitted from the exit surface parallel to longitudinal axis 42, will be substantially less than is the case of a truncated conical design wherein the bottom surface 52a is a flat surface as opposed to the bottom of the lens ending in a tip 58 (i.e. the apex of the cone).
  • the optimum position for the bottom surface 52a is determined by the position of the peripheral light ray 57'.
  • the top enclosure portion 44 of the light source housing completely covers the top flat surface 58' of lens 45 so that the peripheral ray 57 which exits forming a 45 angle with the vertical or longitudinal axis 42, intersects the entry surface 55 at 59, thus establishing the optimum location for the bottom surface 57.
  • the position of the bottom surface 57 may be altered to vary the ratio of light rays emitted at an angle of 45 relative to the light rays emitted which are parallel to the longitudinal axis 42.
  • FIG. 4 shows the optimum lens design giving dimensions and angular relationships for all of the lens surfaces.
  • FIG. 4a shows a perspective view of the resulting lens configuration of FIG. 4.
  • the advantages of the light source configuration of the instant invention can thus be appreciated from a consideration of FIGS. 5a and 5b, with FIGS. 6a and 6b, respectively.
  • the radiation pattern for the light rays 71 is a circular pattern 72.
  • the intersection of all light rays 71 upon the circular curve 72 are equal in intensity.
  • the radiation pattern is shown by the curve 74 which has a cardioidic shape.
  • the vertical light ray 75 i.e.
  • an undeflected light ray has an intensity value of 1.0.
  • Light rays at the maximum deflection angle of 45 from the vertical axis have intensity values of 2.5.
  • light rays which will be directed toward the periphery-of the tube face shown in FIG. 1 is.
  • light rays undergoing the maximum deflection from the vertical have a greatly increased intensity value relative to the undefiected light rays 75, whereas compared with the ideal point light source shown in FIG. 5a, the light rays directed toward the edges of the tube face are at best equal in intensity to the undeflected light rays and, as a practical matter, are found to be substantially lower in intensity than the vertically-directed light ray 71'.
  • this curve 76' has a circular shape as does the curve 73 shown in FIG. 512 so that the light rays are on the directional in the horizontal plane.
  • the instant invention provides a novel light source configuration for use in shadow-mask color tube light house structures in which the light rays striking the tube face during the phosphor dot positioning process are greatly enhanced in intensity as compared with conventional methods.
  • Apparatus for use in lighthouse structures employed for forming the phosphor dot pattern in shadow mask color tubes comprising a housing for supporting a tube 7 face and associated shadow mask, said apparatus being positioned within said housing and comprising:
  • a second housing having an opening
  • a lens positioned within said second housing opening for deflecting light rays directed toward said opening toward said color tube face wherein the light rays directed toward the edges of said tube face are substantially greater in intensity than the light rays directed toward the central region of said tube face.
  • entry surface is contained substantially within said housing and said exit surface projects outwardly from said second housing through said opening.
  • said reflector means has a curved reflecting surface which is substantially el-liptically shaped; said source of light being positioned substantially at the prime'focal point of the elliptically shaped curve.
  • said lens has an entry surface positioned within said second housing; and an exit surface projecting outwardly from said second housing through said opening; said exit surface being inclined at an angle to the longitudinal axis for said lens; said angle being selected to maximize the number of light rays emitted from said lens and directed toward the marginal edges of said tube face.
  • exit surface is inclined at a second angle relative to said lens longitudinal axis; said angle being in the range from 41 to 49.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Formation Of Various Coating Films On Cathode Ray Tubes And Lamps (AREA)
  • Non-Portable Lighting Devices Or Systems Thereof (AREA)
  • Optical Elements Other Than Lenses (AREA)
  • Lenses (AREA)
US513033A 1965-12-10 1965-12-10 Light source for shadow mask tubes Expired - Lifetime US3380354A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
US513033A US3380354A (en) 1965-12-10 1965-12-10 Light source for shadow mask tubes
GB53166/66A GB1159818A (en) 1965-12-10 1966-11-28 Light Source.
NL6616697A NL6616697A (fr) 1965-12-10 1966-11-28
DE19661462871 DE1462871B2 (de) 1965-12-10 1966-12-07 Lichtquelle zur herstellung des leuchtstoff-punktrasters von farbfernseh-bildroehren
FR86780A FR1504229A (fr) 1965-12-10 1966-12-09 Source lumineuse à intensité orientée

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US513033A US3380354A (en) 1965-12-10 1965-12-10 Light source for shadow mask tubes

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US3380354A true US3380354A (en) 1968-04-30

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US513033A Expired - Lifetime US3380354A (en) 1965-12-10 1965-12-10 Light source for shadow mask tubes

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US (1) US3380354A (fr)
DE (1) DE1462871B2 (fr)
FR (1) FR1504229A (fr)
GB (1) GB1159818A (fr)
NL (1) NL6616697A (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3452657A (en) * 1966-07-18 1969-07-01 William J G Cox Multiple pin-hole camera
US3509802A (en) * 1966-12-29 1970-05-05 Sylvania Electric Prod Cathode ray tube exposure optics
US4152154A (en) * 1970-06-05 1979-05-01 U.S. Philips Corporation Method of optically projecting a pattern of substantially circular apertures on a photosensitive layer by rotating light source

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR920007032A (ko) * 1990-09-22 1992-04-28 김정배 칼라브라운관의 노광장치

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2817276A (en) * 1955-02-01 1957-12-24 Rca Corp Manufacture of color-kinescopes, etc.
US2941457A (en) * 1954-09-15 1960-06-21 Rca Corp Apparatus for use in the manufacture of mosaic screens for color-kinescopes, etc.
US2942099A (en) * 1958-04-11 1960-06-21 Rca Corp Optical projection system
US3211067A (en) * 1962-06-15 1965-10-12 Rauland Corp Method of exposing a multi-color target structure
US3259038A (en) * 1963-12-27 1966-07-05 Sylvania Electric Prod Light attenuator

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2941457A (en) * 1954-09-15 1960-06-21 Rca Corp Apparatus for use in the manufacture of mosaic screens for color-kinescopes, etc.
US2817276A (en) * 1955-02-01 1957-12-24 Rca Corp Manufacture of color-kinescopes, etc.
US2942099A (en) * 1958-04-11 1960-06-21 Rca Corp Optical projection system
US3211067A (en) * 1962-06-15 1965-10-12 Rauland Corp Method of exposing a multi-color target structure
US3259038A (en) * 1963-12-27 1966-07-05 Sylvania Electric Prod Light attenuator

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3452657A (en) * 1966-07-18 1969-07-01 William J G Cox Multiple pin-hole camera
US3509802A (en) * 1966-12-29 1970-05-05 Sylvania Electric Prod Cathode ray tube exposure optics
US4152154A (en) * 1970-06-05 1979-05-01 U.S. Philips Corporation Method of optically projecting a pattern of substantially circular apertures on a photosensitive layer by rotating light source

Also Published As

Publication number Publication date
NL6616697A (fr) 1967-06-12
DE1462871A1 (de) 1969-01-23
FR1504229A (fr) 1967-12-01
DE1462871B2 (de) 1972-05-10
GB1159818A (en) 1969-07-30

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