CA1135428A - Beam-index line-screen television display systems - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
Beam-index line-screen television display systems are disclosed for generating multi-color images throughout the size range from small direct view cathode ray tubes to projection type wall screen configurations. The image in the small screen display is generated by a scanning electron beam whereas the image generated in the large screen configuration is developed by a scanning optical beam. In both cases the excitation of the image producing target screen is synchronized by beam-indexing features which utilize optical index signals transmitted across the target screen.

Description

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BEAM-INDEX LINE-SCREEN TELEVISION DISPLAY SYSTEMS
This application is a division o~ Canadian Serial No. 349,93~, filed April 15, 1980, which is a division of Canadian Serial No. 255,8~9, filed ~une 28, 1976.

CROSS-REFERENCE TO RELATED APPLICATIONS
This application is related to Canada Serial No. 951,396 filed February 3, l9G6 and now Patent No. 809,293, issued March 25, 1969.
BACKGROUND OF THE INVENTION

(1) Field of the Invention One aspect of the invention disclosed in the above referenc-ed application which is expanded upon in this application is the feature whereby a scanning beam of energy is made to impinge upon a targe-t screen comprising optical fibers or light pipe members which are used to -transmit optical radiation across the target screen. Specifically, optical index radiation is transmitted parallel to -the target screen generally from i-ts interior regions to its periphery where it is used for beam~ cle~ing purposes to control the generation of multi-color displays.
Another aspect of the above referenced invention which is expanded upon herein relates to the generation of large screen displays wherein a scanning optical beam excites a line-screen target placed at a distance from the source of -the optical beam.
In particular, one embodiment is envisaged wherein a screen is placed against or mounted on a wall, as a picture in a frame, to be excited by a scanning optical beam in order to produce a color picture. Index radiation is developed, to synchronize the excitation of the target screen, and is concentrated for trans-mission either through the air or via electrical or optical cables to a color signal processor which modulates the scanning beam. If a cable configuration is used, it is con-templa-ted that the cable may be run across -the ceiling of the room as an added convenience.

(2) Description of -the Prior Art Beam-inclex color cathode ray tubes have been proposed by _ 1 _ ~35~
~ ny workers, in many countries, and several working prototypes have been described in the open Iiterature. Generally speaking they have not been characterized by high brightness which rules out their use in projection television schemes. As a consequence most low cost, large screen color displays have resorted to the use of three cathode ray tubes, each developing a different color picture which is projected in careful registration upon a viewing screen. Several high cost projection systems have been developed, and some marketed commercially, which rely on phase gratings, and optically deformed surfaces but these are not rela-ted to the instant invention except as to the final result achieved, namely, a large screen full color display operati~g in the television mode. See, for example, True U.S. Patent 3,730,992.
Another system for a large screen television type raster scan-ned display is typified by a three beam laser system equivalent to the three CRT combination referred to above. Pinnow et al U.S. Patent 3,652,956 describes a variation of this type of dis-play in which the red color is produced at -the tarcJet screen.
To applican-t's knowledge, there is no prior art which des-cribes the use of a line-screen beam-index display system which generates a large screen full color display by optical scanning as set forth in applicant's above referenced ap~licatioll.
Furthermore, with respect to either direc-t view or projection displays the prior art of others is silent insofar as applicant's teachings are concerned wherein the index radiation generated at the viewing screen is detected by the scintillation process, thereby to capture a large amount of the index radiation. Light '~
pipe transmission is utilized in conjunction with the scintillat-ion process and this too is believed to be set forth in television type raster scan color display apparatus solely by applicant in this application, and in his prior teachings.

The search for a successful low cost projection type color apparatus has persisted for a long tinle. See, for example, Von Ardenne U.S. Patent 2,265,657 which was filed 35 years ago, ~ 1939. And then note the recent comment attribu-ted to the representative of a leading inte]-na-tional producer of color television receivers which is reproduced here:

The Prime Minister's statement that no import quo-tas would be placed on colour television sets coming into Australia has been welcomed by the senior managing director of the Sony Corporation of Japan.
* * *
Mr. Yoshie said in ten years consumers would be able to purchase television sets ranging from one inch to wall size.
~ ABC Newsroom Canberra, A.C.T., Australia 7:00 p.m., 27 April 1974 The instant invention describes a system which can be manufactured to yield these results immediately.
SUMMARY OF THE INVENTION
Generally, the inven-tion disclosed pertains to improved methods and means for generating, collec-ting, and concentrating optical index radiation from cathode ray tubes or projection type display screens. Optical index radiation which deno1:es the position of the scanning beam o energy is light piped parallel to the image generating display screen to the periphery thereof. Adjacent the periphery is an elongated light pipe-scintillator which responds to the light piped optical index radiation to produce a secondary optical index signal. The secondary optical index signal is concentrated in the elongated light pipe-scintillator to emerge at an exit end thereof in con-centrated form. This arrangement provides a s-trong optical index signal, of small dimensions. It also provides for a compact assem-bly of the index signal concentrator with the display screen so asto efficiently use the space surrounding the display screen. This arrang`ement is particularly advantageous for l al--Je screen dLspl~iys.

~L~35~3 More particularly, one aspect of the invention to which the claims in this divisional application are directed, per-tains to an improved beam-index line-screen color cathode ray tube having an envelope with an electron gun section for pro-viding a scannable electron beam and faceplate section with a target screen having a repeating array of different color producing strips for generating a viewable target, the tar-get screen also having index-signal generating means which provide optical index signals indicative of the position of impact of the electron beam on the target screen. The optical index signals are transmitted transversely of the target screen by a plurality of spaced apart optical light pipes disposed inside the envelope, adjacent the target screen, in register with the color producing strips. Means for combining the optical index signals comprise an elongated light pipe-scintillator disposed to receive and be excited along its length by the optical index signals transmitted transversely of the target screen, thereby to generate a set of second optical index signals.
Another aspect of the claimed invention comprehends a line-screen beam-index multi-color cathode ray tube including an electron beam source and a transparent faceplate with strip-like regions of different color producing elements on the inside surface thereof r and in register therewith spaced apart other strip-like regions for producirlg electron beam locating optical index signals for transmission along and within the faceplate by light pipe action to the periphery thereof. An elongated light pipe-scintillator is disposed adjacent the periphery to receive and be excited along its length by the optical index signals and thereby to provide ~L~35~

a set of second optical index signals.
A still further aspect of the claimed invention relates to a beam-index line~screen color cathode ray tube having an envelope with an electron gun section for providing a scannable electron beam; a frusto-conical intermediate section; and a faceplate section with a target screen having a repeating - array of different color producing strips, ~or generating a viewable image, in register with a plurality of spaced apart strips of phosphor affixed to the interior side of the face-plate for generating optical index signals indicative of theposition of impact of the electron beam on the target screen.
A continuous layer of a transparent light pipe-scintillator is disposed on the exterior side of the faceplate and is responsive to the optical index signals transmitted through the faceplate thereby to generate second optical index signals which are light piped to the per.iphery of the light pipe-scintillator. Elongated light pipe-scintillator means are disposed at the periphery for receiving and being excited by the second optical index signals, thereby to generate a set of third optical index signals.

BRIEF DESCRIPTION OF TEIE DRAWING
Figure 1 illustrates in block diagram format a display system using a projectiOn type cathode ray tube (CRT) and a refracti~e lens system for transmitting the image developed by the cathode ray tube to a target screen.
Figure 2 illustrates in block diagram format a display system using a laser as a source of light which is modulated and scanned across a target screen.

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Figure 3 i]lustrates in exaggerated perspective a target screen, for use with the arrangernent of Figures 1 and 2, comprising repeating groups of red, blue, and green light emitting strips interspersed with optical light pipes which generate optical index signals.
Figure 4 depicts a CRT arrangement, alternate to Figure 1, wherein the color pic-ture is developed in the cathode ray tube prior to the image being projected on the target screen. The arrangement of Figure ~ can also be used for direct viewing.
1'~ Figure 5 illustrates in exaggerated perspecti~e a target screen akin to that in Figure 3 wherein a plurality of optical light pipes, interspersed with the color emitting strips, transmit their optical index signals to impinge upon the side wall of another light pipe whereby cliffeLent index siyn.lls aL`~
combined lnto a signal on a con~on path.
Figure 6 ~lepic-ts a target screen, akin to that of Figure 5, inside a cathode ray tube. The cornbining of the index signals takes place inside the tube envelope.
Figure 7, taken in conjunction with Figures 8 - 11, depicts a sectional view of a cathode ray tube akin to Figure 6 but wherein the plurality of optical light pipes are brought through a frit seal joining the faceplate to the funnel of the tube. Means for cornbining the optical signals in the light pipes are shown disposed outside the envelope of the tube.
Figure 8 is a side view of the faceplate, frit seal, part of the funnel section, and the optical light pipes of Figure 7.
Figure 9 is a side view in section of the faccplate, frit seal, part of the funnel section, and the target screen of Figure 7.
Figure 10 illustrates, in section, an extension of a light pipe being brought through the frit seal.

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Figure 11 illus-trates an optical light pipe being brought through the frit sea], and a secondary light pipe which is used to combine optlcal index signals from a pluralit~ of thc optical light pipes.
Figure 12 depicts a display screen wherein a special substrate is used to generate a primary optical index signal.
Figure 13 is a front view of the display screen of Figure 12 and illustrates a light pipe collector which is clisposed along the edge of the substra-te to clenerate a secondary optical index signal.

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DESCRIPTION OF T~IE PREFERI~FD EMBODIMENTS

In Figure 1, projection type cathode ray tube (CRT) 10 has a target screen 12 which is excited by an electron beam emitted by electron gun 14 and wllicll is scaIIllecl b~ ~lcflection means 16. Scanning currents are provided by ras-ter generator 18. High voltage for the target screen typically is introduced at 15. This construction is conventional.
In one embod:iment oE the ins-tant invention the target screen comprises a layer of P-16 phosphor which, as is well known, radiates in the near ultraviolet peakin~ at about 3800 ~ngstroms when excited by the scanning electron beam.
Modulator 20 controls the intensity of the scanning electron beam as it scans a raster across the target screen. The inputs to the modulator 20 are the luminance signal Y and outputs from color signal processor 22. The processor 22 receives 1~, ~r and G color signals or color difference signals R-Y, B-Y, and G-Y.
These color sig}lals are sampled by pulses clerivecl ~rom the index pulses to provide a sequential train of pùls~s for modu-lating electrodes of the electron gun 14. Varying amounts of luminance signal Y may be added to the sequential train o~
pulses to achieve optimum color balance. The color signals and raster scan are synchronized in conventional fashion.
The end result of the arrangement of Figure 1 is that a scanning beam of modulated ultraviolet ligllt is pro~ecte~ upon display screen 26. To synchronize the excitation of the target screen 12 and thence display screen 26, index signal 2~ is depicted as emanating from the display screen to feed into processor 22. The scanning beam thereby is modulated to generate a full color picture on the screen 26 via intermediate screen 12. The details of screen 26 will be described with respect to Figure 3.

Details of the electronic c:ircuitry are omitted as -they are not necessary for a proper wlderstanding of this invention.
Nevertheless for completeness reference is made to my ~. S.
Patent 3,564,121 where beam modulation and index control features are set forth. ~eference is also maclc ~o L~c~lesq~ a et al U~ S. Patent 3,715,611 for alternates to the conventional P-16 phosphors.
In the arrangement of Figure 1 just described the scanning electron beam generates on target screen 12 a rapidly decayillg synthetic ultraviolet replica of the image to be generated by display screen 26. This feature differs from the conventional flying spot scanner where the o~tical scannillg beam rr~m th~
CRT is of constant intensity. No-te also that beam-index control of the replica of the image is derived not from the CRT but from the remote display screen. Color signal processor 40 preferably is situated proximate the CRT 10 but may be placed near screen 26 if desired.
In Figure 2 an alternate and conventiollal arr~llgcmellt is shown for developing the synchronized and modulatecl scanning light beam. Thus, instead of CRT 10 which generates an intermediate monochrome "image" there is a laser licJht source 30 modulated by means 32 with color signals furnished by processor 40. The raster generator 38 is synchronized with the color signals R, B, G or R-Y, B-Y, G-Y. Scanner 3~ deflects the laser light beam to trace out a raster patterll. Prefer.~
- the scanning beam is in the ultraviolet. Index signal ~2 is derived from target screen 36 as will be described next.
In ~igure 3 an enlarged perspective is illustrated of a target screen 50 with strip-like members 51, 52, and 53 which produce red, blue and green light, respectively, in response to excitation by the scanning beam of op-tical energy. In the ~35~28 preferred embodiment scanning takes place across the target screen to excite in sequence an index strip 54l and then 51, 52, 53 followed by index strip 56, etc.
Index strip 54 (and 56, 58, 60) is made of a plastic scintillator such as N~-102 supplied by Nuclear En~el-prises in San Carlos, Calif. In response to excitation by the ultraviolet scanning beam, it generates an optical index signal which is light piped, as depicted at 63, to exit terminal 62. ~t the other end of the index s-trip 54 it is light piped along length 55.
The target screen 50 may be thin, and rollable, in wllich case the index strips are filamentary in nature. They may also be square as depicted at 55 or round as at 57. The target screen may be rigid, and self-supporting, in which case rectangular ribbons of light pipe-scintillator 59 and 60 may be preferred.
The optical index signals may be preserved in optical form as illustrated at~55, 57, 59 of Figurc 3 or ~l~e)~ L~ collv~.
to electrical signals by photo-detectors illustrated at 62, ~0 64, 66 and 68. The photo-detectors may be spaced from the light pipes as at 64, 66, and 68 or they may be positioned on the exit terminal as at 62. Power supply 70 furnishes bias for the photo-detectors. Conventional P-22 phosphors are suitable materials for the color producing strips 51, 52, 53.
Photo-detectors 62, 64, 66 and 68 may be conventio~al l~i-3h speed photo-diodes.
It will be readily appreciated by those skilled in beam-index technology that the screen 50 of Figure 3 provides all that is needed to fulfill the re~uirements oE screen 26 of Figure 1 and screen 36 of Figure 2. It will also be appreclated that the structure 50 of Figure 3 can be modified for incorpora-tion into a ~RT as depicted in Figure 4 where op-tical index ~35~
ignal 25 is light piped within the CRT as set Eorth in more detail in the previously referenced patent. See also Turner U. S. Patent 3,311,773 for reference to a material suitable for the index stîips in a CRT. Electrical index signal 24 may be derived from the faceplate. Also, optical indc~ 24' n~ay ~e derived at the faceplate as will be described. The numeration of the other elements in Figure 4 correspond to like elements in Figure 1.
The optica] index signals in Figure 3 are combined by physically bringing together the exit terminals of the light pipes. A superior arrangement is shown in Figure 5 where the plurality of optical index signals are combined via the scintillation process. Thus, in Figure 5, index s~rips 71, 72, 73, typically are made of NE-102 which generates a blue-white index radiation in response to excitation by ultraviolet light.
This blue-white radiation is plped up the target screen to impinge upon light pipe-scintillato:r 7~. Typically, element 74 is made of N~-103 also manuEactured by Nuclear rlntcrprises.
This scintillator has the property of responding to tlle blue-white excitation of ~E-102 thereby to generate longer wavelength optical radiation which is light piped to exi-t terminals 75 and 76.
Thus, before and after the scanning beam traverses color producing strips 51, 52, 53 it will excite index strips 71, 72, 73 which in turn will excite strip 74. By this ~roccss a combined optical index signal emerges a-t 75 and 76 in the form o a series or train of pulses separated in time. It is these pulses which are then used to effect proper registration of the colors on the display screen.
At the bottom of Figure 5, secondary light pipe-scintillator 77 is depicte~ feeding its output into photo-detector 78. Bias 1~5~
for the photo-detector is provided by power source 79, and electrical ou-tput is at 80. Comparison of Figure 5 with Figure

3 shows clearly the reduction in electrical connections which are brought about by using the secondary scintillator to collect and concentrate the output from the index strips.
Note also the reduction in photo-detectors from Eo~r to ol~e.
In practice, the reduction in complexity is much more stri~ing because a typical multi-color display will contain many more than the mere four (4) s-trips used here for illustration and explanation.
In Figure 6, a target screen a~in to that of Figule 5 is inserted in a CRT. Faceplate 84 is shown joined to funnel section 82 via frit seal 86. The index signal combiner 74 is passed through the frit seal to bring the combined optical index signal to the outside of the CRT envelope. F~.lement 7~
in this embodiment should withstand CRT processing temperatures.
To comply with this requirement, element 74 can be made of suitable glass tubing to be filled with a liquid scintillator after the CRT is completed.
Alternate construction of the CRT of Figure G is illustrated in Figures 7 - 11. Red, blue, and green emitting phosphor strips 51, 52, 53 are deposited on the inside of faceplate 84.
In register therewith are index signal producing strips 71 such as light pipe-scintillators as set forth in my ~rliel (`al~ atellt 809,293. Faceplate 84 is joined to funnel section 82 via frit seal 86. Four of the light ~ipes 71 are shown bringing tlleir inde~

radiation to the outside of the tube through the frit seal 86.
At the bottom of Figure 7, index signal combiner 95 is shown.
~t may be made of ei-ther NE-102 or NE-103 as both will respond to the excitation of the ultraviolet index radiation light piped through 71. Element 95 is shown to be recessed sliglltly ~35~

in Figures 7, 8, and 9 which is a convenience and not a necessity. ~t the top of Figure 7, the index signal combiner 93 is spaced slightly away from the faceplate. Note also from Figure 10 that index light pipe 71 may be coupled to anotller light pipe section 97 which may be chosen to be more compatible with the frit seal 86.
Note also in Figure 9 that the conventional aluminum l~ayer, designated 91, is situated on top of both the color producing phosphors 51, 52, 53 and the index strips 71, 97.
This simplifies considerably the construction of the CRT
because the coi~plicated and relatively intrica-te step of layiny the index strip on top of the thin and fragile aluminum layer is dispensed with.
Two other ways of elimina-ting this important step in the manufacture of a co:Lor CRT have been set forth previously.
One way makes use of the light pipe action in the facepla-te and funnel section o the C~T to transmit ancl concetltr~te thc inclex signal. Witil fri-t seal 86 this becomes difficult. The other way is to surround the front exterior of the faceplate 84 with a smooth and continuous transparent scintillator 85, such as NE~102, which responds to the index radiation (generated by index strips 71, 97, etc.) transmitted through faceplate 84.
The optical index signals developed within the transparent - scintillator equivalent to 85 are collected and concelltrated in a funnel shaped extension surrounding the CRT envelope. In this specification, an elongated additional scintillator 87, such as NE-103, is used to collect and concentrate tile index radiation.
See also Figures 12 and 13 which teach in the alternative that faceplate 8q may be made of a transparent scintillator (see Turner 3,311,773) which responds to electron beam 35~4f~1B
excitation. In this configuration, for a C~T, the color producing strips 51, 52, 53 are relatively thick to absorb the electron beam and the index strips 71, 97, etc.,`are supplied by narrow strip-like openings in the color producing strips.
Secondary scintillator 89 may be a strip of NE-102 to collect and CQncentrate the index radiation.
Returning to the wall screen structure, the teachings of Figure 7 are applied in modified form to the structure of Figures 12 and 13. An ultraviolet scanning beam is depicted at 107. Fluorescent materials 51, 52, and 53 emit red, blue, and green light, respectively, in response to excitàtioIl by scanning beam 107. A rectangular block of scintillator 102 supports the colox emi-tting strips 51, 52, 53. A reflective layer 104 such as aluminum may separate the fluorescent strips from the backing of scintillator 102. A clcarance passage 100 permits the scanning beam to excite the scin-tillator 102.
Passage 100 thus becomes the index marker in tllat material 102 will scintillate when it is implnged upon by the scanning beam.
Scintillations generated in the interior of 102 are light piped to its periphery. Positioned adjacent the periphery is secondary scintillator 106 which responds to the optical radiation produced by scintillator 102 thereby to generate the secondary or output optical index signal. ~lement 106 is shown to surround the rectangular block 102 but it may ~e positioIlcd less than full way around and still function effectively.
Also, filter element 101 is shown if it is desired to reduce the effects of ambien-t illumina-tion. This Eilter is narrow band, selected to pass primarily the wavelengths of the optical scanning beam. And, lastly, reflective or blocking member 108 surrounds the remainder of the target screen to prevent excess ambient illumination from exciting the scintillators.
Scintillator 102 may be NE-102 and scintillator 10~ may be NE-103, as previously identified.

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Attention is drawn to the compact arran~ement whicll results from this configuration and that of Figures 7 - 10. See Canada Patent 743,198 wllich discusses the desirability of volumetrie efficiency.
For detailed information on scintillators which may be used with this invention, reference is made to Organic Seintillation Detectors by E. Schram, Elsevier Publishing Co., 1963. See also l~yman U. S. Patent 2,710,284. ~For details frit seaiing reference is made to Claypoole U. S. Patent 2,889,952.
Conventional P-22 phosphors are cited previously in this diselosure. Alternatively, eommon fluorescent paints may be used. It is also possible to use R, G, and s filter elements in eombination with white eolor emittin~ phosphors as a substitute eonfiguration for the -target sereen. The light pipe-seintillators may be made of a single material or they may eonsist of a core and "claddinc~" and still pL~ovide tlle featuxes set forth in this specifieation.

Although the optieal seanning beam preferably is in the ,.~
ultraviolet region of the speetrum, other wavelengths may be ~ substituted with appropriate ehanges in strips 51, 52, and 53.
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For example, a short-wave blue seanning beam may be used with a blue-to-blue converter seleeted for color producing strip 52 and with NE-103 used for the index strips 54,56, and 58 of Figure 3.
Whether the display screen is front or rear projection, note that all -three colors result from emitted light ratller then reflected light. This type of "living" screen provicles a wide viewing angle.
Lastly, it was mentioned at the outset o this specifiea-tion that one of the reasons for not employing a beam-index ~1;3S9L;~
color CR~ as the primary source of the image in a projection television apparatus was -the inability of the prior art to develop a sufficiently bright color picture. ~nother long standing difficulty in prior art direct view beam-index kinescopes has been that of extracting an index signal with a good signal to noise ratio. Accordingly, it is fair to state that not only does this invention provide a good, crisp index signal for kinescopes but it also solves an even molc illtellSe problem, namely, the derivation of a good index signal from a wall screen display.

Claims (11)

The embodiment of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a beam-index line-screen color cathode ray tube having an envelope with an electron gun section for providing a scannable electron beam and faceplate section with a target screen having a repeating array of different color producing strips for generating a viewable image, said target screen also having index-signal generating means which provide optical index signals indicative of the position of impact of the electron beam on the target screen; the improvement wherein said optical index signals are transmitted transversely of the target screen by a plurality of spaced apart optical light pipes disposed inside said envelope, adjacent said target screen, in register with said color producing strips, and means for combining the optical index signals comprising an elongated light pipe-scintillator disposed to receive and be excited along its length by the optical index signals transmitted transversely of the target screen, thereby to generate a set of second optical index signals.

2. The cathode ray tube of Claim 1, wherein the faceplate section is joined to the envelope of the tube by a frit seal, and wherein the elongated light pipe-scintillator is disposed within the envelope but extends through the frit seal, thereby to transmit said second optical index signals to the exterior of the tube.

3. The cathode ray tube of Claim 1, wherein the faceplate section is joined to the envelope of the tube by a frit seal, and wherein the plurality of optical light pipes extend through the frit seal to transmit the optical index signals to the exterior periphery of the tube, and means for combining the thus-transmitted optical index signals.

4. The cathode ray tube of Claim 1, wherein the means for combining the optical index signals comprises scintillator means, responsive to said optical index signals, positioned outside the tube to receive and be excited by said optical index signals thereby to generate a set of second optical index signals.

5. The cathode ray tube of Claim 3, wherein said elongated light pipe-scintillator is disposed along the periphery of the faceplate to receive and be excited along its length by the optical index signals transmitted through the frit seal.

6. A line-screen beam-index multi-color cathode ray tube comprising an electron beam source and a transparent faceplate with strip-like regions of different color producing elements on the inside surface thereof, and in register there-with spaced apart other strip-like regions for producing electron beam locating optical index signals for transmission along and within the faceplate by light pipe action to the periphery thereof, in combination with an elongated light pipe-scintillator disposed adjacent said periphery to receive and be excited along its length by said optical index signals, thereby to provide a set of second optical index signals.

7. The combination of Claim 6 including an elec-trically conductive electron permeable layer situated on top of the color producing elements and said other strip-like regions.

8. The combination of Claim 7 wherein the transparent faceplate is made of a material which scintillates in response to electron beam impingement, and wherein spaced apart openings between the color producing elements provide said other strip-like regions for producing the electron beam locating optical index signals.

9. A beam-index line-screen color cathode ray tube having an envelope with an electron gun section for providing a scannable electron beam, a frusto-conical intermediate section, and a faceplate section with a target screen having a repeating array of different color producing strips, for generating a viewable image, in register with a plurality of spaced apart strips of phosphor affixed to the interior side of said face-plate for generating optical index signals indicative of the position of impact of the electron beam on the target screen, in combination with a continuous layer of a transparent light pipe-scintillator, disposed on the exterior side of said face-plate, responsive to the optical index signals transmitted through said faceplate thereby to generate second optical index signals which are light piped to the periphery of said light pipe-scintillator, and elongated light pipe-scintillator means disposed at said periphery for receiving and being excited by said second optical index signals, thereby to generate a set of third optical index signals.

10. The combination of Claim 9, wherein said periphery scintillator means comprises a hollow thin-walled light pipe of frusto-conical shape, surrounding said intermediate section, for transmitting and concentrating said second optical index signals.

11. The combination of Claim 9, wherein said spaced apart strips of phosphor and said faceplate are made of the same material, and wherein said array of different color producing strips have narrow strip-like openings which coincide with said spaced apart strips.