DE1243715B - Index color picture display tube - Google Patents

Description

GERMAN 4ffl? WW8> PATENT OFFICE

EDITORIAL HOlj

German class: 21 al - 32/54

Number: 1243 715

File number: R 38327 VIII a / 21 al

J 243 715 filing date: July 9, 1964

Opened on: July 6, 1967

The invention relates to an index color display tube with a piston, which an electron gun, a color phosphor layer containing phosphors emitting different colors and means for generating an index signal circuit with one by the electron beam contains stimulable phosphor, and with a window arranged in the bulb wall, through which the index signal radiation can reach the outside from the inside of the piston.

A well-known index tube contains a fluorescent mosaic screen with an arrangement of colored phosphor groups, each of which a number of light of different colors emitting fluorescent strips included, which run parallel to each other and perpendicular to the beam deflection. On the back of the Color phosphor strips are spaced apart from one another and run parallel to the color phosphor strips Strips arranged from an ultraviolet light emitting phosphor. The piston of the tube is behind the luminescent screen with a UV-permeable window, so that one outside of the UV-sensitive photocell arranged in a tube piston can record UV identification or index signals, which arise when the cathode ray crosses the spaced apart UV fluorescent strips is distracted.

In the case of a device that works with an index tube, a step-shaped index signal is generated within the tube generated having at least three levels, e.g. B. the signal amplitude zero, one Can correspond to a maximum value and an intermediate value. Has to generate such a signal hitherto two different arrangements of UV fluorescent index strips have been used. The one arrangement comprises thinner layers than the other and provides the index signal with the mean amplitude level. The generation of signals of different amplitudes by phosphor deposits of different Thickness is only possible if there are close tolerances in terms of the layer thicknesses, which is both difficult and costly.

A significant percentage of the total energy of the Electron beam are absorbed in the index fluorescent strips. Because the strips are spaced apart are arranged, the absorption is intermittent and leads to uneven excitation of the fluorescent colored strips representing the image. This effect known as shading results in a disturbing pattern in the reproduced image.

Index color display tube

Applicant:

Radio Corporation of America,
New York, NY (V. St. A.)

Representative:

Dr.-Ing. Ε. Sommerfeld, patent attorney,
Munich 23, Dunantstr. 6th

Named as inventor:
Roger Dunwoody Thompson,
Lancaster, Pa .;
Harold Bell Law,
Princeton, Ν. J. (V. St. A.)

Claimed priority:

V. St. v. America 9 July 1963 (293 611),

dated August 26, 1963

(304 311)

The present invention is based on the object of specifying an index color display tube, in the case of disruptive shading caused by the arrangement generating the index signal radiation be avoided.

In the case of a tube of the type mentioned at the outset according to the invention, this object is achieved by that the arrangement for generating the index signal radiation is a cohesive phosphor layer, arranged on the side of the colored phosphor layer facing the beam generating system is, and a pattern of precipitates of radiation-absorbing and / or radiation-reflecting Material arranged on at least one side of the cohesive phosphor layer are that they intercept, absorb or reflect the radiation emanating from this layer, contains.

An index color television picture tube is already known from the USA patent specification 3 018405, in which the arrangement for generating the index signal contains a contiguous layer which the fluorescent color layer covered. However, this contiguous layer is a layer made of a material with high secondary emissivity, which together with conductor strips

709 609/304

acts on which the index signal is picked up. The well-known, coherent layer is in theirs So function with the coherent phosphor layer used in the subject matter of the invention not comparable.

With regard to the further developments and refinements of the invention, in order to avoid repetitions referred to the subclaims.

The invention will now be explained in more detail with reference to the drawing, it shows

Fig. 1 is a perspective, partially sectioned view of an index color picture tube according to the invention, the visible part of the tube's screen arrangement is shown greatly enlarged,

F i g. FIG. 2 is an enlarged sectional view of the luminescent screen of the FIG. 1 tube shown in one level 2-2,

F i g. 2 a is a graphical representation of the course of the from the in F i g. 2 generated screen Index signal,

F i g. 3 and 4 sectional views of luminescent screens according to other embodiments of the invention, in the in F i g. 1 can be used, and

F i g. 3 a and 4 a graphical representations of the course of the by the luminescent screens F i g. 3 or 4 generated index signals.

The F i g. 1 and 2 show, as an exemplary embodiment of the invention, a cathode ray tube 10 with a bulb 12 in which a luminescent screen 14 that can be excited by electrons is arranged. The bulb also contains a beam generation system 16 which delivers an electron beam directed onto the screen. The piston 12 is provided with a window 18 behind the screen 14 , the purpose of which will be explained later.

The luminescent screen 14 contains a mosaic layer 20 made of fluorescent strips which emit light of different colors. The strips can, for example, alternately consist of phosphors that emit red, blue, green and yellow and are denoted by R, B, G and Y , respectively, in the drawing. The mosaic 20 consists of a plurality of repeating color phosphor groups 21 each containing an R, B, G and Y stripe. During operation, the electron beam is deflected perpendicular to the colored phosphor strips via the luminescent screen 14. The special properties of the color phosphor groups 21, e.g. B. the width of the colored stripes, the spectral characteristics of the emitted light, the number of stripes per group and the order of the colors within the individual groups can be selected in a known manner. For example, you can also work with a mosaic of red, blue and green-emitting fluorescent strips.

On the back of the mosaic 20, so the beam forming system 16 may facing side, a light-reflecting layer 22, for example. B. a vapor-deposited aluminum layer can be arranged.

A continuous phosphor layer 24 is arranged next to the mosaic 20. With screen assemblies that include a reflective layer 22, there is the phosphor layer 24 on the reflective layer 22. The layer 24 preferably consists of a phosphor primarily emitting in the ultraviolet. For example, a calcium magnet activated with cesium and lithium

Si-silicate phosphor, as it is known under the designation P16, can be used. However, other ultraviolet-emitting phosphors or phosphors which emit visible light or other radiation when excited by electrons can also be used for the phosphor layer 24 .

A first layer is located between the phosphor layer 24 and the light-reflecting layer 22

ίο arrangement of spaced apart strip-shaped deposits 26 which are practically impermeable to the luminescent radiation emitted by the phosphor layer 24. The absorbing strips 26 run symmetrically and parallel to the colored fluorescent strips R, B, G, Y of the mosaic 20. For each three colored fluorescent strip groups 21 , for example, one absorbing strip 26 can be provided. The individual absorbent strips 26 can cover colored fluorescent strips R, B, G, Y, R, B and part of a fluorescent strip G. However, other width, spacing and periodicity ratios of the absorbing strips 26 with respect to the fluorescent colored strips R, B, G, Y of the mosaic M are also possible.

On the luminescent layer 24 there is a second arrangement of spaced-apart strip-shaped deposits 28 which are practically impermeable to the luminescent radiation emitted by the luminescent layer 24. The radio-opaque strips 28 are each arranged centrally opposite corresponding absorptive strips 26 . The impermeable strips 28 are much narrower than the impermeable strips 26; the width of the strips 28 can be approximately * / s to ^z U of the width of the strips 26 .

The absorbing strips 26 consist of a material which practically completely absorbs the luminescent radiation emitted by the cohesive phosphor layer 24 and incident on it. For the absorbent strips 26 , for example, powdered carbon or finely divided powdered aluminum, such as is known as aluminum black, can be used.

The opaque strips 28 can consist of a similar material that absorbs the luminescence radiation, or also of a material that reflects the luminescence radiation, such as flake-shaped or leaf-shaped aluminum powder. Why one can use these different types of materials for the strips 28 will be explained later.

In operation, the cathode ray tube 10, the beam generating system 16 provides a cathode ray, det by an unshown deflector in such a way on the luminescent screen 14 is deflected such that the data written from the beam line perpendicular to the color phosphor stripes R, B, G, Y, the absorbent strip 26 and the Stripes 28 impermeable to emission radiation run. When the electron beam is deflected over the luminescent screen 14 , the phosphor layer 24 is continuously excited to luminescence. If the electron beam is deflected over an area a and strikes the phosphor layer 24 where there is neither an absorptive strip 26 nor a radio-opaque strip 28 , a maximum of luminescence radiation is emitted backwards m the bulb 12 and through the window 18.

shine. If the electron beam scans a region b and strikes a part of the phosphor layer 24 under which an absorbing strip 26 lies, the luminescence radiation emitted to the rear has a medium amplitude. This is because the portion of the radiation emitted primarily forwards is absorbed by the strips 26 and prevented from exiting the screen 14. When the electron beam scans an area c and strikes a radio-opaque strip 28, practically all of the luminescence radiation is absorbed or reflected, depending on how the strips 28 opaque to the emission radiation are composed, so that no luminescence radiation can escape from the screen. The strips 28 are intended to completely prevent the luminescent radiation from escaping from the screen 14 and can therefore either absorb or reflect.

The fact that the beam produces an index signal of lower amplitude in region b (FIG. 2) than in region a is due to the presence of the reflective layer 22. When the electron beam excites the phosphor layer 24, the luminescence radiation is both forward and backward emitted. In area a , the forwardly directed luminescence radiation is reflected by the reflective layer 22 and is added to the backward emitted radiation, so that both the forward and backward emitted luminescent radiation emerge from the screen. In the region b , the luminescence radiation emitted forwards is absorbed by the absorbing strips 26, so that it can no longer exit the screen. Only about half of the usable luminescence radiation, namely the radiation primarily emitted to the rear, emerges from the screen 14.

In Fig. 2a the course of the three-stage signal is shown, which arises when the screen 14 is scanned. The amplitude levels a ', b', c 'of the in FIG. 2 a represented signal correspond to a scanning of the areas a, b and c (Fig. 2) by the electron beam. The amplitude level corresponds to the maximum output amplitude, b 'to a mean output amplitude and c' to the output amplitude zero.

The luminescence radiation emerging from the screen 14 to the rear is allowed to pass through the window 18 and falls on a device 29, e.g. B. a phototube, which is on the from the phosphor layer 14 emitted index signals. The signals generated by the radiation-sensitive device 29 can be used in a known manner to synchronize the color modulation and the scanning of the from System 16 supplied electron beam can be used.

F i g. 3 shows a screen 30 according to an embodiment of the invention, which provides a four-level index signal. The screen 30 contains a mosaic 31 of red-emitting, blue-emitting and green-emitting color phosphor strips, which are labeled R, B and G, respectively. As with the screen 14 of FIG. 2, a light-reflecting layer 22 and a phosphor layer 24 are applied to the mosaic 31. On the phosphor layer 24 there are index strips 32, 33, 34 of different transparency. Virtually completely impermeable strips 32 of the arrangement are each arranged between two transparent strips 33. Outside

the transparent strips 33 are followed by two further, even more transparent strips 34. The impermeable Strips 32 can for example consist of coal particles. The more transparent strips For example, 33 may contain a material such as boron nitride mixed with a small amount of carbon. The even more transparent strips 34 can be made of boron nitride, which has an even smaller proportion of Carbon is added, or consist of pure boron nitride.

When the electron beam scans an area d (FIG. 3) of the screen 30, an output signal d ' (FIG. 3 a) of maximum amplitude is radiated backwards. When the beam hits an area e , the signal emitted backwards has a somewhat smaller amplitude e ', since the strips 34 absorb a small part of the luminescent radiation. When the electron beam strikes a region /, the amplitude of the signal radiated backwards from the screen has the smaller value f, since the index strips 33 absorb more. When the beam hits an area g of the screen, practically no luminescence radiation can exit the screen to the rear, so that the signal amplitude g ' (FIG. 3 a) has practically the value zero. According to the dimensioning of the width and transmission ratios of the index strips 32, 33, 34, a four-stage index signal results, as shown in FIG. 3 a is shown.

If a two-stage index signal is to be generated, a single opaque index strip can be used made of a material that reduces the luminescence emission of either the phosphor solid layer absorbs or reflects in place of the index strips 32, 33, 34 (FIG. 3) of different permeability step. For these individual strips, for. B. absorbent materials, such as carbon powder, or reflective materials such as vapor-deposited aluminum.

F i g. As an embodiment of the invention, FIG. 4 shows a screen 35 which also has a four-stage index signal supplies. The screen 35, like the screen 30 of FIG. 3 a three-color mosaic 31, a reflective one Layer 22 and a phosphor layer 24 in the order given. Between the reflective Layer 22 and the phosphor layer 24 is an arrangement of index strips 36 from a partially absorbent material such as boron nitride. An arrangement of partially permeable Strips 38, which can be made of the same material as the stripes 36, are on top of the phosphor layer 24. The individual strips 38 are each centered opposite an associated one Strips 36 arranged. In the middle on the various partially transparent strips 38 is respectively a strip 40 of an array of practically impermeable strips, for example of carbon, is arranged.

When an electron beam strikes an area h of the screen 35, the luminescence output radiation has a maximum amplitude value // (FIG. 4a). If the electron beam hits an area i , part of the forwardly directed luminescence radiation is absorbed by a strip 36 6g, and the output radiation has a somewhat smaller amplitude / '. When the electron beam hits a region j , it becomes part of both the forward and the backward

Claims (7)

directed luminescence radiation is absorbed by the index strips 36, 38, and the amplitude of the output signal is accordingly even smaller. If the electron beam hits a region k, practically all of the luminescence radiation is absorbed and the amplitude kf of the output signal is practically zero. The screen 14 shown in FIG. 2 is easy to manufacture, since the index strips 26, 28 are practically completely impermeable to the luminescent radiation emitted by the phosphor layer 24. It will be understood that screens containing only fully absorbent strips 26, 28 are easier to manufacture than screens in which a medium amplitude signal is generated by appropriately dimensioning the composition and / or thickness of a strip deposit. The index strips 26, 28, 32, 33, 34, 36, 38, 40 are preferably made of a material of relatively low density or relatively low atomic mass, since the strips then absorb only little radiation energy and shading is largely avoided. It is particularly expedient to use a material for the index strips which, compared to the phosphor layer 24, has a lower molecular mass or lower density. Even in cases in which the material of the index strips has a greater density than the phosphor of the layer 24, the weight per unit area of the index stripes, which is required for the required impermeability, can nevertheless be less than the weight per unit area of a phosphor strip, which is required to generate an index signal of sufficient amplitude. The screen 14 can be constructed as follows, for example: The mosaic 20 can consist of strips of red-, blue-, green- and yellow-emitting phosphors that are 508, 380, 432 and 203 μm wide and have a weight per unit area of 2.6 to 2.9, 1.3 to 1.5, 2.0 to 2.2 and 1.3 to 1.5 mg / cm2. The reflective layer 22 can consist of vapor-deposited aluminum and be approximately 4000 Å thick. An index strip 26 can be provided for each of three fluorescent dye groups 21. The index strips 26 may be evenly spaced strips of colloidal graphite that are 2.62 mm wide and cover fluorescent strips R, B, G, Y, R and part of another fluorescent strip G, respectively. The phosphor layer 24 can consist of UV-emitting lanthanum phosphate phosphor with a weight per unit area of approximately 0.25 mg / cm 2. The index strips 28 can consist of colloidal graphite, be approximately 1.85 mm wide and lie in the middle on the index strips 26. The weight per unit area of the index strips 26, 28 can be below 0.1 mg / cm 2 and so small that no visually recognizable or measurable absorption of the radiation energy occurs. The components of the luminescent screen 14, that is to say the colored mosaic strips 20, the light-reflecting layer 22, the phosphor layer 24 and the index strips 26, 28, can be produced by known methods. The carbon strips 26, 28 can be produced, for example, by applying a sensitized slurry containing carbon particles to the reflective layer 22 or the phosphor layer 24 and then rendering the applied layer insoluble in the desired locations by actinic UV radiation or electron bombardment . Patent claims: 1. Index color display tube with a bulb which contains an electron gun, a color phosphor layer containing differently emitting phosphors and an arrangement for generating an index signal radiation with a phosphor that can be excited by the electron beam, and with a window arranged in the bulb wall through which the index Signal radiation can pass from the inside of the bulb to the outside, characterized in that the arrangement for generating the index signal radiation has a coherent phosphor layer (24) which is arranged on the side of the colored phosphor layer (20, 31) facing the radiation generating system (16) , and a pattern of deposits (26, 28; 32, 33, 34; 36, 38, 40) of radiation-absorbing and / or radiation-reflecting material, which are arranged on at least one side of the continuous phosphor layer in such a way that they intercept the radiation emanating from this layer , absorb or re inflect, contains. 2. Tube according to claim 1, characterized in that the pattern contains radiation-reflecting deposits (26, 36) which are arranged between the colored phosphor layer (20, 31) and the continuous phosphor layer (24) (Figs. 3 and 5). 3. Tube according to claim 1 or 2, characterized in that the pattern contains an arrangement of precipitates (28; 32, 33, 34; 38, 40) which on the side of the coherent phosphor layer (20, 31) facing away from the colored phosphor layer ( 24) are arranged. 4. Tube according to claim 3, wherein the arrangement providing the index signal radiation contains an ultraviolet-emitting phosphor, characterized in that the pattern contains spaced apart deposits (28, 32, 40) of an opaque material, which with respect to the Patterns of the color phosphor layer are systematically arranged and intercept ultraviolet radiation from corresponding parts of the coherent phosphor layer (22). 5. Tube according to claim 3, characterized in that the pattern contains deposits (32, 33, 34) of different absorption capacities for the radiation emitted by the cohesive phosphor layer (24). 6. Tube according to claim 5, characterized in that the pattern is strip-shaped deposits contains different transparency, which are arranged and dimensioned so that a multi-level Index signal arises (Fig. 3, 3 a). 7. Tube according to claim 1 or 2, characterized in that the pattern deposits (26, 36) which are arranged on the side of the coherent phosphor layer (24) adjacent to the color phosphor layer (20, 31) , as well as deposits (28; 38, 40), which is based on the color