US3883880A - Exposure apparatus for manufacturing fluorescent screens of colour picture tubes - Google Patents

Exposure apparatus for manufacturing fluorescent screens of colour picture tubes Download PDF

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Publication number
US3883880A
US3883880A US424092A US42409273A US3883880A US 3883880 A US3883880 A US 3883880A US 424092 A US424092 A US 424092A US 42409273 A US42409273 A US 42409273A US 3883880 A US3883880 A US 3883880A
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United States
Prior art keywords
lens
correction
panel
composite
fluorescent screen
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
US424092A
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English (en)
Inventor
Eiichi Yamazaki
Koichi Maruyama
Toshio Ueda
Iwao Ogura
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Hitachi Ltd
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Hitachi Ltd
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Publication date
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    • 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
    • H01J9/20—Manufacture of screens on or from which an image or pattern is formed, picked up, converted or stored; Applying coatings to the vessel
    • H01J9/22—Applying luminescent coatings
    • H01J9/227—Applying luminescent coatings with luminescent material discontinuously arranged, e.g. in dots or lines
    • H01J9/2271—Applying luminescent coatings with luminescent material discontinuously arranged, e.g. in dots or lines by photographic processes
    • H01J9/2272—Devices for carrying out the processes, e.g. light houses

Definitions

  • ABSTRACT A composite correction lens means including two superposed correction lenses is used to cause the exposure light to travel along a path approximating the actual locus of an electron beam in a colour picture tube.
  • Each correction lens has a wedge shaped sectional configuration.
  • a shield disc having a perforation for exposing a selected area of the fluorescent screen is disposed between the composite correction lens means and the fluorescent screen. The relative angular position between the shield disc and the composite correction lens means is made variable.
  • This invention relates to an exposuredevice utilized to manufacture a fluorescent screen of a colour picture tube.
  • a fluorescent screen of a shadow mask type colour picture tube is formed with regularly arranged phosphor dots or stripes by means of photographic technique.
  • the path of the exposure light should coincide with the locus of the electron beam in the colour picture tube in order to reproduce pictures of high quality. Accordingly. it is important to control the path of the exposure light during the exposure operation by bending the path.
  • correction lenses having continuous or discontinuous curved surfaces of complicated construction have been used. With such correction lenses it has been impossible to completely align the landing point of the electron beam spot with the phosphor dot or phosphor stripe.
  • correction lenses of complicated construction are difficult to manufacture because a large cost. long period and a large number of process steps are required. According to an improved method.
  • a slit is interposed between a source of light and the correction lens and the slit is moved relative to the source of light and the correction lens for partially exposing the fluorescent screen thereby improving the accuracy of the landing of the electron beam spot upon the phosphor dot.
  • this method requires to use a special point light source of high brightness so that the exposure apparatus is complicated and the movement of the light source results in errors.
  • It is an object of this invention is to provide an improved exposure apparatus utilized to manufacture a fluorescent screen of a colour picture tube and capable of improving the accuracy of the landing of the electron beam spot upon phosphor dots or stripes thus producing pictures of high qualities.
  • Another object of this invention is to provide an improved exposure apparatus utilized to manufacture a fluorescent screen of a colour picture tube and capable of providing an improved wide angle colour picture tube in which colour shading at the peripheral portion of the tube is eliminated.
  • a correction lens is interposed between a source of light and the fluorescent screen.
  • the correction lens takes the form of a composite correction lens means including two superposed correction lenses.
  • a shield member provided with a perforation for exposing a selected area of the fluorescent screen is positioned between the fluorescent screen and the composite correction lens means. and that the relative angular position of the composite correction lens means and the shield member is made variable.
  • Each correction lens has a wedge shaped sectional configuration with a curved effective surface or a rectangular shaped sectional configulation with inclined surfaces divided by discontinuous border lines on its effective surface. Not only the relative angular position between the shield means and the composite correction lens means but also the relative angular position between two correction lenses are made variable.
  • FIG. 1 is a diagrammatic sectional view of a prior art exposure apparatus for manufacturing a fluorescent screen of a colour picture tube;
  • FIG. 2 is a diagram showing a manner of landing of an electron beam spot upon a phosphor dot
  • FIG. 3 is a vector diagram to explain the landing condition of the electron beam spot shown in FIG. 2;
  • FIG. 4A shows a plan view of a wedge shaped correction lens
  • FIG. 4B shows a cross-section of the lens shown in FIG. 4A taken along a line IVB IVB'.
  • FIG. 4C shows a cross-section of the lens shown in FIG. 4A taken along a line IVC IVC;
  • FIG. 5A shows a plan view of one embodiment of the composite correction lens of this invention
  • FIG. 5B shows a sectional view of the lens assembly shown in FIG. 5A taken along a line VB VB;
  • FIG. SC shows a sectional view of the lens assembly shown in FIG. 5A taken along a line VC VC;
  • FIG. 6A is a plan view showing a modified composite correction lens of this invention.
  • FIG. 6B is a sectional view of the lens assembly shown in FIG. 6A taken along a line VIB VIB;
  • FIG. 6C is a sectional view of the lens assembly shown in FIG. 6A taken along a line VIC VIC;
  • FIG. 7A is a plan view showing another form of the composite correction lens of this invention.
  • FIG. 7B is a sectional view of the lens assembly shown in FIG. 7A taken along a line VIIB VIIB;
  • FIG. 7C is a sectional view of the lens assembly shown in FIG. 7A taken along a line VIIC VIIC;
  • FIG. 8A is a plan view of a composite correction lens showing the relative position of lenses which is useful to explain the direction of correction of a correction vector;
  • FIG. 8B is a sectional view of the lens assembly shown in FIG. 8A taken along a line VIIIB VIIIB;
  • FIG. 8C is a sectional view of the lens assembly shown in FIG. 8A taken along a line VIIIC VIIIC,
  • FIG. 9 is a perspective view of the essential elements of an exposure apparatus embodying the invention.
  • FIGS. 9A. 9B and 9C show perspective views of shield discs having openings of different configurations
  • FIGS. 10A shows still another embodiment of the composite correction lens embodying the invention
  • FIG. IOB is a sectional view of the lens assembly shown in FIG. 10A taken along a line XB XB and FIG. 10C is a sectional view of the lens assembly shown in FIG. 10A taken along a line XC XC.
  • an exposure apparatus 1 usually termed a lighthouse and comprising a source of light 2 and a correction lens 3, as shown in FIG. 1.
  • a face plate or panel provided with a shadow mask 4 is mounted on the exposure apparatus 1.
  • the correction lens 3 functions to modify the path of the exposure light emanated from the source of light 2 such that the light travels along a path approximating the actual locus of the electron beam in the colour picture tube.
  • the fluorescent screen, not shown. coated on the inner surface of the face plate 5 is exposed to light transmitting through the shadow mask 4.
  • the exposed fluorescent screen is then fixed by photographic technique to form phosphor dots.
  • the correction lens generally has continuous or discontinuous curved surfaces of complicated configurations. This provides fairly satisfactory correction. With recent trend of using wide angle colour picture tubes, it becomes difficult to accurately make the path of the exposure light to approximate the actual locus of the electron beam, especially at the peripheral portion of the effective area of the flourescent screen.
  • the vector A representing the misalignment is decomposed into a horizontal component Ax and a vertical component Ay which are expressed as follows as functions of the position.
  • a small area that can be represented by the following equations is considered AX a (3) Ay C (4) where C and C are constants, and the maximum value of the misalignment in this small area is considered over the entire area of the fluorescent screen. More particularly, the effective area of a fluorescent screen is considered to be an aggregate of such small areas. In a local aggregate, it is considered that the vector of misalignment is independent of the position and one half of the maximum value of the vector of misalignment in a local aggregateis used to design a correction lens.
  • lAl max expressed by an equation lAl is taken and the correction lens is desi ned to correct an amount of misalignment equal to l I max/2.
  • the correction lens 11 will have a wedge shaped cross-sectional configuration in which its upper or effective surface is inclined in the direction of .r alone as shown in FIGS. 4A. 4B and 4C.
  • the correction lens II will have a configuration ofa simple prism, the inclined surface being curved to eliminate the effect of thickness.
  • A is a sealer quantity. It is necessary to correct not only its magnitude but also its direction.
  • FIG. 8 One example of such correction is illustrated in FIG. 8.
  • the assembly shown in FIG. 7A is rotated by an angle :1) with the relative angle d between two lenses unchanged whereby the direction of correction is varied while the magnitude thereof established by the relative angle d), maintained constan t Accordingly. it is possible to correct misalignment A in any small areas in the entire area of the fluorescent screen of the colour picture tube.
  • FIG. 9 shows one example of the novel exposure apparatus utilizing the composite correction lens described above.
  • the exposure apparatus shown in FIG. 9 comprises a lower correction lens 15 having a wedge shaped sectional configuration and rotated by a gear or roller 18, an upper correction lens 14 having similar sectional configuration and rotated by a gear or roller 17 and a shield disc 20 positioned above the correction lens 14 and rotated by a gear or roller 21, the disc 20 being provided with a perforation 25 which projects the exposure light from a source oflight 19 only upon a desired area on the fluorescent screen coated on the inner surface of the face plate 16 through shadow mask 22.
  • the invention is especially suitable for wide angle colour picture tubes.
  • the perforation 25 may take any desired configuration as shown in FIGS. 9A, 9B and 9C that is elliptical, polygonal or sector shape. so long as the perforation can project the exposure light upon the desired area of the fluorescent screen.
  • FIG. shows another embodiment of the composite correction lens of the invention.
  • Correction lenses shown in FIGS. 4 through 8 had a wedge shaped configuration and their upper surface were curved to eliminate the effect of thickness.
  • the upper or effective surface of the correction lens is shaped in the form of saw teeth with discontinuous border lines 23 between inclined flat surfaces 24.
  • Respective surfaces 24 may have the same angle of inclination so that it is possible to readily manufacture the correction lens.
  • the border lines 23 and surfaces 24 of the lower correction lens 27 are skewed with respect to those of the upper correction lens 26 which is equivalent to relative rotation of two correction lenses shown in FIG. 7.
  • the invention provides an improved exposure apparatus utilizing a composite correction lens including two superposed correction lenses so that by adjusting the relative position of these lenses it is possible to adjust the direction of refraction as well as the intensity of the exposure light. thus enabling to improve the accuracy of alignment of the electron beam spot with the phosphor spot of the fluorescent screen of not only relatively narrow angle colour picture tubes but also wide angle colour picture tubes. This prevents formation of colour shading and improves picture quality.
  • an exposure apparatus for manufacturing a fluorescent screen of a colour picture tube of the class wherein a correction lens is interposed between a source of light and an assembly of a shadow mask and panel on which said fluorescent screen will be developed the improvement which comprises composite correction lens means including at least two correction lenses.
  • a shield member positioned between said composite correction lens means and said assembly, said shield member provided with a perforation for exposing a selected area of said panel, and means for varying the relative angular position of said composite correction lens means and said shield member for moving said selected area over a selected portion on said panel corresponding to the correction provided by said lens means.
  • each of said correction lenses of said composite lens means has a wedge shaped sectional configuration and the effective surface of the lens is curved.
  • each correction lens of said composite lens means is provided with means for rotating the same.
  • An exposure apparatus which further comprises means for rotating said composite lens means while maintaining the corrective lenses thereof at a constant angular relationship.
  • each of said correction lenses of said composite lens means has a rectangular shaped sectional configuration and effective surface of the lens.
  • an exposure apparatus having a light source and a correcting lens means, for manufacturing a fluorescent screen of a color picture tube having a shadow mask and a face panel on which the fluorescent screen is to be developed, the improvement comprising:
  • a light source assembly positioned to expose the inner surface of the panel portion through the mask
  • a complex lens system having at least two correcting lenses to approximate the light path from said light source to an actual electron beam path of a color picture tube in operation;
  • a shield member provided with a perforation limiting light exposure to a selected inner surface area of the panel by confining the light emanated from said light source through said perforation;
  • a driving system including a plurality of individual driving means to give a rotary motion to each of said correcting lenses and said shield member so as to adjust a relative angular position thereof;

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Formation Of Various Coating Films On Cathode Ray Tubes And Lamps (AREA)
US424092A 1972-12-25 1973-12-12 Exposure apparatus for manufacturing fluorescent screens of colour picture tubes Expired - Lifetime US3883880A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP47129272A JPS4988465A (de) 1972-12-25 1972-12-25

Publications (1)

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US3883880A true US3883880A (en) 1975-05-13

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US424092A Expired - Lifetime US3883880A (en) 1972-12-25 1973-12-12 Exposure apparatus for manufacturing fluorescent screens of colour picture tubes

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US (1) US3883880A (de)
JP (1) JPS4988465A (de)
DE (1) DE2364113C3 (de)
GB (1) GB1422838A (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4135930A (en) * 1974-03-07 1979-01-23 Matsushita Electronics Corporation Method for manufacturing the phosphor screen of color-picture tube
US5671460A (en) * 1994-03-31 1997-09-23 Kabushiki Kaisha Toshiba Exposing apparatus
US6469842B1 (en) * 1999-07-15 2002-10-22 Mitsubishi Denki Kabushiki Kaisha Apparatus for patterning a phosphor screen, having a main lens with flat elements replaceable by sub-lenses

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3476025A (en) * 1966-06-15 1969-11-04 Rca Corp Cathode ray tube and method of manufacture
US3736848A (en) * 1970-10-20 1973-06-05 Tokyo Shibaura Electric Co Method of preparing the screen of a colour television picture tube and device performing the method
US3738234A (en) * 1971-05-08 1973-06-12 Philips Corp Exposure device for manufacturing a display screen of a color television picture tube
US3783754A (en) * 1971-03-05 1974-01-08 Hitachi Ltd Method and apparatus for manufacturing color picture tubes

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3476025A (en) * 1966-06-15 1969-11-04 Rca Corp Cathode ray tube and method of manufacture
US3736848A (en) * 1970-10-20 1973-06-05 Tokyo Shibaura Electric Co Method of preparing the screen of a colour television picture tube and device performing the method
US3783754A (en) * 1971-03-05 1974-01-08 Hitachi Ltd Method and apparatus for manufacturing color picture tubes
US3738234A (en) * 1971-05-08 1973-06-12 Philips Corp Exposure device for manufacturing a display screen of a color television picture tube

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4135930A (en) * 1974-03-07 1979-01-23 Matsushita Electronics Corporation Method for manufacturing the phosphor screen of color-picture tube
US5671460A (en) * 1994-03-31 1997-09-23 Kabushiki Kaisha Toshiba Exposing apparatus
US6469842B1 (en) * 1999-07-15 2002-10-22 Mitsubishi Denki Kabushiki Kaisha Apparatus for patterning a phosphor screen, having a main lens with flat elements replaceable by sub-lenses

Also Published As

Publication number Publication date
DE2364113B2 (de) 1978-10-26
DE2364113C3 (de) 1979-07-05
JPS4988465A (de) 1974-08-23
DE2364113A1 (de) 1974-06-27
GB1422838A (en) 1976-01-28

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