US3356881A - Cathode ray tube with a perforated aluminum film graticule overlying the illuminescent layer - Google Patents

Description

Dec. 5, 1967 1.. s. YAGGY 3,356,881

CATHODE RAY TUBE WITH A FERF'ORAIEU ALUMINUM FILM GRATICULE OVERLYING THE TLLUMlNESCENT LAYER Filed Oct 4, 1965 2 SheetsSheet 1 Leon S. Yclggy,

INVENTOR.

ATTORNEY.

Dec. 5; 1967 1.. s. YAGGY 3,356,881

CATHODE RAY TUBE WITH A PERFORATED ALUMINUM FILM GRATICULE OVERLYING THE ILLUMINESCENT LAYER 2 Sheets-Shet 2 Filed Oct. 4, 1965 Leon S/Yoggy;

INVENTOR.

ATTORNEY.

United States Patent CATHODE RAY TUBE WITH A PERFORATED ABSTRACT OF THE DISCLOSURE The invention provides an integral graticule pattern for a cathode ray tube. Specifically, an aluminum coating is provided overlying and engaging the phosphor electron beam illuminescent coating. An aluminum coating thickness of approximately 1,000 A. is suggested, whereby the coating, per se, is opaque to visible light yet accommodates electron passage to induce illumination of the phosphor effecting normal tube operation. The aluminum coating is provided with patterned gaps which define a visible graticule when the aluminum coating is bathed with visible light.

The invention relates to a cathode ray tube and particularly to a tube incorporating an illuminated graticule and to the method of manufacturing the tube incorporating the graticule.

Cathode ray oscilloscope tubes .are used in the art to provide a visual display of wave patterns or other timevarying phenomena. In connection with the visual display, it is sometimes desirable to provide a graticule associated with the display to aid in the analysis thereof. Typically the graticules comprise a network of lines perpendicularly related and spaced or otherwise arranged in some predetermined relationship to the phenomena being studied.

The graticules used in tubes heretofore have fallen into two general categories, namely, external graticules and internal graticules. External graticules usually involve the positioning of a transparent, generally planar element having the graticule lines etched therein in front of and spaced from the oscilloscope viewing screen. An edge light or other source of illumination is positioned adjacent the plate and provides a source to illuminate the graticule. Typical internal graticules are formed by etching the inner glass surface of the viewing screen to the desired pattern and thereafter coating the inner surface with appropriate illuminating substance such as phosphor. Again,'an edge light is utilized to provide a source of graticule illumination.

These and other prior art devices presented some difficulties in use. For example, the edge light illuminating source, while visually exposing the graticule, also illuminated the phosphor screen, resulting in extremely poor contrast on the display. Additionally, the graticules that were mounted on a separate external element were, of necessity, in spaced relation to the area of visual display and resulted in difficulties and inaccuracies in reading depending upon the position of the viewing operator. It

will thus be apparent that prior art cathode ray oscilloscope graticules have not proved entirely satisfactory to persons skilled in the field.

With the above in mind, it is a primary object of the invention to provide a cathode ray tube having an integral graticule formed therein without affecting display contrast required for accurate phenomena analysis.

It is a further object of the invention to provide a mode of providing a displayed graticule on the display screen to thus provide accurate phenomena analysis.

3,356,881 Patented Dec. 5, 1967 ICC It is yet a further object of the invention to provide a cathode ray tube having a displayable graticule formed by utilizing an extremely thin metallic film which is opaque to light and providing in the film a pattern of openings in predetermined relationship to each other so that when the film is bathed by a source of conventional illumination, a graticule pattern will appear on the tube display screen. The metallic film is of such thickness that it will permit electron penetration while preventing light penetration from the illuminating source.

It is still another object of the invention to provide a method of manufacturing the unique cathode ray tube having an internal graticule as herein disclosed.

These and other objects of the invention will become apparent in the course of the following description and from an examination of the related drawings, wherein:

FIG. 1 is a perspective view of a cathode ray oscilloscope tube having a viewing screen incorporating the invention;

FIG. 2 is an enlarged fragment of a sectional view taken along line 2-2 of FIG. 1;

FIG. 3 is an enlarged fragment of a sectional view similar to FIG. 2 showing an alternate construction;

FIG. 4 is a sectional view taken at 4-4 of FIG. 2;

FIG. 5 is a sectional view taken at 5-5 of FIG. 3; and

FIG. 6 is a fragmentary perspective view illustrating the structure employed in the method of manufacture of the tube here under consideration.

'cathode down the major axis of the tube; an arrangement of electrodes called deflecting plates located beyond the gun and used to direct the electron beam; and a target or screen placed in a plane substantially perpendicular to the axis of the gun and coated with a phosphor material, which becomes illuminescent when struck by the electrons. The entire assembly is, of course, encapsulated in a glass container or envelope or a metal container having a glass viewing window and the container is evacuated to provide a vacuum therein. Frequently, the tube is utilized in the study of cyclic, repetitive, transient phenomena or in the study of non-repetitive transient phenomena having extremely short time durations.

As an aid in the noted studies and the analyses thereof, graticules have heretofore been developed for the cathode ray tubes. As noted above, conventional graticules may be be of the internal or external variety, that is, etched into the glass viewing screen or associated with an independent transparent elements which is mounted in front of the viewing screen. The difiiculty in re loss of contrast between the visible graticule and the display because the illuminating source of the gratilule illuminated the phosphor as well has been noted.

In FIG. .1, the numeral 10 generally indicates a cathode 'ray tubehaving a viewing screen 12 incorporating the herein disclosed invention. The screen 12 is preferably made of glass and a segment thereof is shown in FIG. 6. Normally, a thin coating of phosphor is placed over the internal surface of the viewing screen 12. A conven- Directing attention to FIG. 6, a segment of the viewing screen 12 is here shown and it will be assumed that the inner surface 14 thereof has been conventionally coated with a thin film of illuminating phosphor. A thin plastic film is then placed over the phosphor to provide a smooth surface for the subsequent aluminizing operation. A wire mesh mask 16 having elements 18 and 20 corresponding, in pattern, to the desired graticule pattern is then positioned on the plastic film. The elements 20 may be provided with short segment wire elements 22 extending transversely thereof, again, in a relationship corre sponding to the finally desired graticule pattern. The elements 18 may be provided with upbraided inverted U- shaped segments 24, 24 intermediate the elements 20, the purpose of which will hereinafter be described.

After positioning of the wire mesh 16, the arrangement is subjected to a conventional aluminum evaporating process to provide a thin aluminum film coating. The wire mesh 16 masks portions of the phosphor surface, preventing aluminum disposition thereon. After the aluminum evaporative step is complete, the mesh 16 may be removed and an aluminum film having the surface pattern shown in FIGS. 2 and 4 is provided. A second baking operation fixes the arrangement and destroys the aluminum supporting plastic film.

In FIG. 4 it will be noted that in a preferred form of the invention, the aluminum film 26 provides a pattern on the inner surface of the viewing screen which has gaps formed therein as at 28, 28 corresponding to the elements 18 and perpendicular gaps 30, 30 corresponding to the Wire elements 20 of the screen 16. Additionally, aligned gaps 32 are formed in the aluminum film 26 and correspond to the short wire segments 22 of the mesh 16. It

is noted that the inverted U-shaped sections 24 provide neck segments 34 of aluminum film electrically joining all sections of the aluminum film 26. Thus, the aluminum film may be used to discharge the screen in tube operation and the charging of electrically isolated segments of aluminum film during tube operation is avoided. However, the inverted U-shaped sections 24 of mesh 16, which allows formation of neck 34, may be eliminated in one form of the invention hereinafter discussed.

As disclosed in FIGS. 2 and 4, the completed tube has a target or viewing screen having the window 12 of glass, and, on the inner surface 14, a first layer of film of phosphor material and a second pattern interrupted layer of aluminum film 26. The interruptions 28, 30 and 32 of the aluminum film provide a graticule pattern when subjected to illumination from an independent source such as lamp 40 (FIG. 1). If desired, the lamp 40 may be mounted externally of the envelope 10 and a transparent window 42 provided to allow the illumination to bathe the inner surface of the target. The major portion of the aluminum film 26 is opaque to light. A graticule pattern 44, however, corresponding to the interruptions or openings in the aluminum film will appear on the screen 12 when the latter is bathed in visible light. If desired, the illuminating source such as lamp. 40 may also be located internally of the envelope 10.

As an alternate form of construction, attention is di rected to FIGS. 3 and 5. The inner surface 14a of the viewing screen 12 may be coated with a transparent electrically conductive discharge layer 48. A coating of phosphor 15a and aluminum film 26a may be positioned thereon as above described. In this form of construction, the inverted U-shaped wire elements 24 are omitted from the mesh 16 during aluminum evaporation. Thus, isolated segments of aluminum film 26a are formed on the inner surface of the screen (FIG. 5). The layer 48 is here used to discharge the target and will also discharge the isolated segments 2611.

It will thus be apparent that the structure described and method of manufacture provides an oscilloscope tube having a viewing or display screen with an integrally formed graticule associated therewith. In use as above described, a high degree of contrast between display and graticule is offered. Accidental phosphor illumination is avoided. The structure also aids in substantially reducing operator reading error.

The invention as shown is by way of illustration and not limitation, and may be modified in many aspects, all within the scope of the appended claims.

What is claimed is:

1. In a cathode ray tube, a transparent viewing element; a first film of material, illuminescent in response to an electron bombardment, coating the inner surface of the element; and a second film of electron transparent and light opaque material having openings therein defining a graticule pattern coating the first film of material.

2. A cathode ray tube according to claim 1, wherein said second film is surface positioned on the first film.

3. A cathode ray tube according to claim 2, wherein said second film is an electrically conductive metallic film, said openings defining metallic film segments electrically joined by metallic film necks.

4. In a cathode ray tube, a transparent viewing element, a first film of electrically conductive light transparent material coating the inner surface of the element, a second film of material illuminescent in response to electron bombardment coating the inner surface of said first film, and a third film of electron transparent and light opaque material having openings therein defining a graticule pattern adjacent the second film.

5. A cathode ray tube according to claim 4, wherein said openings define electrically isolated segments of said third film, said first film being operative to discharge the viewing element in tube operation.

6. In a cathode ray tube arrangement to provide a visible graticule pattern during tube display operation, the combination of a generally transparent viewing element, a film of electron illuminescent material coating the inner surface of the element, a second film of electron transparent and visible light opaque material having openings therein defining said pattern, said second film coating the first film, and a source of visible light to bathe said second film and create a visible pattern display on said viewing element.

7. A cathode ray tube according to claim 6, wherein said source of visible light is positioned externally of the tube, said tube including a transparent window accommodating passage of said visible light to bathe said second film.

References Cited UNITED STATES PATENTS 2,189,583 2/1940 Hollmann 313-92 2,316,550 4/ 1943 Bigalke 1787.87 2,571,723 10/1951 Jonker et al 313-92 ROBERT SEGAL, Primary Examiner.

JAMES W. LAWRENCE, Examiner.

V. LAFRANCHI, Assistant Examiner.

Claims (1)

1. IN A CATHODE RAY TUBE, A TRANSPARENT VIEWING ELEMENT; A FIRST FILM OF MATERIAL, ILLUMINESCENT IN RESPONSE TO AN ELECTRON BOMBARDMENT, COATING THE INNER SURFACE OF THE ELEMENT; AND A SECOND FILM OF ELECTRON TRANSPARENT AND LIGHT OPAQUE MATERIAL HAVING OPENINGS THREIN DEFINING A GRATICULE PATTERN COATING THE FIRST FILM OF MATERIAL.

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