Method and apparatus for electron beam control

Claim 3

A method according to claim 1 in which the step of detecting differential excitation is carried out to produce a signal corresponding to the differential excitation ratio rather than to an arithnetic excitation difference, which signal is then applied to modify the deflection of the beam.

Claim 4

A method according to claim 1 in which during the line scan the progress of said spot is detected by means of at least one of said guide stripes to produce a signal applied to the line scan deflection to accelerate or decelerate the scan so as to maintain the scan velocity constant.

Claim 5

A method according to claim 1 in which the step of detecting differential excitation is carried out by comparing the amplitude of two frequencies produced by the scanning of said guide stripes by said spot as the result of the respective patterns of said guide stripes in the form of width modulation along their length at two respective frequencies.

Claim 6

A method according to claim 1 which includes the step of increasing the intensity of the beam during at least part of the time the said spot is in said line entry guide area.

Claim 7

A method according to claim 1 in which a plurality of beams are deflected with the use of common deflection means to scan lines slightly displaced from each other, in which further only one of said beams is deflected in such a path that its spot impinges on said guide stripes, and in which the said modification of deflection affects all of said beams equally.

Claim 8

A method according to claim 6 in which the beam which is deflected so that its spot scans said guide stripes, is modulated at a predetermined frequency by the effect of which the excitation of said guide areas and said guide stripes by that one of said beams is distinguished from the effects of the other or others of said beams.

Claim 9

A method according to claim 1 in which that one of said beams which is deflected so that its spot scans said guide guide stripes, is unblanked while deflected into said line entry guide area.

Claim 10

A luminescent screen display tube having a luminescent screen including a display portion and a smaller adjacent guide portion and having at least one electron gun means for producing a deflectable electron beam for scanning said screen, said screen being provided over its entire display portion with a series of pairs of guide strips, each pair corresponding to one of the lines of a scan pattern over which the beam of one said gun of the tube is adapted to be scanned, the spacing between the two strips of a pair being smaller than the diameter of the spot produced by the impingement of said beam on said screen, said guides being arranged to produce a detectable excitation upon impingement of said beam in proportion to the area of impingement and being patterned with a width modulation along their length to produce modulation of said excitation during scan, the width modulation of two guides of a pair being at a different pitch.

Claim 11

A luminescent screen display tube having a luminescent screen including a display portion and a smaller adjacent guide portion and having at least one electron gun means for producing a deflectable electron beam for scanning said screen, said screen being provided over its entire display portion with a series of pairs of guide strips, each pair corresponding to one of the lines of a scan pattern over which the beam of one said gun of the tube is adapted to be scanned, the spacing between the two strips of a pair being smaller than the diameter of the spot produced by the impingement of said beam on said screen, said guides being arranged to produce a detectable excitation upon impingement of said beam in proportion to the area of impingement and being patterned with a width modulation along their length to produce modulation of said excitation during scan, the width modulation of two guides of a pair being at a different pitch.

Claim 12

A luminescent screen display tube according to claim 9, wherein the upper and lower guide strips of each pair are constituted by a series of broken lines interrupted by regularly spaced gaps with a pitch that is different as between the two strips of a pair.

Claim 13

A luminescent screen display tube according to claim 9, wherein the width-modulated strips are metallic and the two guide strips of eaCh pair are electrically connected and constitute a a single electrode, whereby the fraction of the beam current containing components which are modulated at the frequencies corresponding to the scanned width modulation may be used to correct the beam deflection.

Claim 14

A luminescent screen display tube according to claim 9, wherein the width-modulated strips are formed of a substance which gives rise under the action of the spot to the emission of an electromagnetic radiation and wherein photoelectric cell means are provided in the proximity of the tube neck for selective detection of such radiation and formation of a signal therefrom.

Claim 15

A luminescent screen display tube according to claim 9, wherein the width-modulated strips are formed of a substance which gives rise under the action of the spot to the emission of a secondary-electron current and means are provided within said tube for detection of said current and obtaining a signal therefrom.

Claim 16

A luminescent screen display tube according to claim 9 for the reproduction of color television images by the three-color process, wherein the guiding strips are each associated with a triplet of three continuous horizontal and rectilinear strips of luminescent material each corresponding to one of the primary colors, and wherein the tube is provided with four electron guns in which a first gun thereof is a master gun and emits a beam impinging on said guiding strips and wherein the three other electron guns or so-called slave guns each correspond to the three primary colors and emit beams which are caused to follow the displacements of the master beam, by being subjected to common deflecting forces, so that corresponding spots move parallel to the guiding beam spot and scan with strict accuracy each of the three luminescent color strips respectively.

Claim 17

A luminescent screen display tube according to claim 14 having associated therewith means for producing magnetic scanning deflection of the beams emitted by said four electron guns and having also means for producing constant centering magnetic fields affecting said beams in such a way that said beams penetrate into the zone in which said magnetic scanning deflection is applied while proceeding as parallel as practically possible to the axis of the tube and as close as practically possible to said axis.

Claim 18

A luminescent screen display tube according to claim 9 adapted for the reproduction of color television images in accordance with the method of horizontal scanning known as interlaced scanning, wherein the guiding strips are each associated with a plurality of luminescent color strips and only some of said strips are scanned by the beams at each half-field.

Claim 19

A luminescent screen display tube according to claim 16 in which each guide strip pair is disposed in predetermined relation to two triplets of luminescent color strips such that when said guide strip pair is scanned in one half frame one of said triplets will be scanned, and when said guide strip pair is scanned in the other half frame the other of said triplets will be scanned.

Claim 20

A luminescent display apparatus including a luminescent screen tube as defined in claim 9 and also including means for deflecting said electron beam as aforesaid and means responsive to the excitation of said guides for correcting the deflection of said electron beam in a direction transverse to said scan lines, said apparatus further including means for detecting variation in frequency or phase of one of the frequencies of variation or of said detectable excitation produced by the scanning of said guides by said spot and for utilizing said frequency or phase variation to modify the deflection of said electron to make the velocity of scan more uniform.

Claim 21

A luminescent screen display apparatus including a luminescent screen display tube according to claim 9 adapted for the reproduction of color television images by the three-color process, wherein said guiding strips are each assOciated with a triplet of three continuous horizontal and rectilinear strips of luminescent material each corresponding to one of the primary colors, and wherein the tube is provided with two electron guns, said apparatus including means for deflecting the beams produced by said guns, means responsive to the excitation of said guiding strips by one of said guns, referred to as the master gun, for modifying the operation of said deflecting means to assure the guidance of the beam of said master gun with reference to said guiding strips and means for causing the beam of the gun other than said master gun, referred to as the slave gun, to be rapidly deflected vertically relative to the beam of said master gun, so that the beam of said slave gun may scan the three luminescent strips of said triplets in a sequence suitable for coordination with successive switching of color video signals.

Claim 22

A luminescent screen display tube having a luminescent screen including a display portion and a smaller adjacent guide portion, and having at least one electron gun means for producing a deflectable electron beam for scanning said screen, said screen being provided over its entire display portion with a series of pairs of guide strips, each pair corresponding to one of the lines of a scan pattern over which the beam of one said gun of the tube is adapted to be scanned, the spacing between the two strips of a pair being smaller than the diameter of the spot produced by the impingement of said beam on said screen, said guides being arranged to produce a detectable excitation upon impingement of said beam such that the excitation of one guide of a pair can be distinguished from that of the other guide of said pair, said guide area of said screen being adjacent to its display area along a boundary to which the ends of all the scan lines of said display area begin, said guide area of said screen including principally pairs of guide zones such that each member of a pair of said zones is separated by the extension of a scan line into said guide area of said screen, said guide zones being arranged to provide a detectable excitation when said beam impinges thereon which is not distinguishable from that of the adjacent guide stripe, but is distinguishable from that produced by the guide stripe just across said scan line from said adjacent guide stripe.

Claim 23

A luminescent screen display tube having a luminescent screen including a display portion and a smaller adjacent guide portion, and having at least one electron gun means for producing a deflectable electron beam for scanning said screen, said screen being provided over its entire display portion with a series of pairs of guide strips, each pair corresponding to one of the lines of a scan pattern over which the beam of one said gun of the tube is adapted to be scanned, the spacing between the two strips of a pair being smaller than the diameter of the spot produced by the impingement of said beam on said screen, said guides being arranged to produce a detectable excitation upon impingement of said beam such that the excitation of one guide of a pair can be distinguished from that of the other guide of said pair, said guide area of said screen being adjacent to its display area along a boundary to which the ends of all the scan lines of said display area begin, said guide area of said screen including principally pairs of guide zones such that each member of a pair of said zones is separated by the extension of a scan line into said guide area of said screen, said guide zones being arranged to provide a detectable excitation when said beam impinges thereon which is not distinguishable from that of the adjacent guide stripe, but is distinguishable from that produced by the guide stripe just across said scan line from said adjacent guide stripe.

Claim 24

A luminescent screen display tube according to claim 20 in which said guide stripes and said guide zones are discontinuous in the direction of the adjacent scan line, in the sense that there are gaps in which the presence of the spot of said beam does not produce the aforesaid detectable excitation produced by the presence of said spot on other portions of said guide stripes and guide zones, and in which said gaps are provided at regular intervals in the direction of said scan line with a pitch on one side of said scan line or its extension in said guide area different from the pitch of said gaps on the other side of scan line or its extension in said scan area.

Claim 25

A luminescent screen display tube according to claim 21 adapted for the reproduction of color television images in accordance with the method of line scanning known as interlaced scanning, wherein the aforesaid guide strips are so provided that adjacent pairs of guide strips have a reversed relation of the relative characteristics of the strips of the pair.

Claim 26

A luminescent screen display tube according to claim 20 for the reproduction of color television images by the three-color process, wherein the guiding strips are each associated with a triplet of three continuous horizontal and rectilinear strips of luminescent material each corresponding to one of the primary colors, and wherein the tube is provided with four electron guns in which a first gun thereof is a master gun and emits a beam impinging on said guiding strips and wherein the three other electron guns or so-called slave guns each correspond to the three primary colors and emit beams which are caused to fOllow the displacements of the master beam, by being subjected to common deflecting forces, so that corresponding spots move parallel to the guiding beam spot and scan with strict accuracy each of the three luminescent color strips respectively.

Claim 27

A luminescent screen display tube according to claim 23 having associated therewith means for producing magnetic scanning deflection of the beams emitted by said four electron guns and having also means for producing constant centering magnetic fields affecting said beams in such a way that said beams penetrate into the zone in which said magnetic scanning deflection is applied while proceeding as parallel as practically possible to the axis of the tube and as close as practically possible to said axis.

Claim 28

A luminescent screen display apparatus including a luminescent screen display tube according to claim 23 adapted for the reproduction of color television images by the three-color process, wherein said guiding strips are each associated with a triplet of three continuous horizontal and rectilinear strips of luminescent material each corresponding to one of the primary colors, and wherein the tube is provided with two electron guns, said apparatus including means for deflecting the beams produced by said guns, means responsive to the excitation of said guiding strips by one of said guns, referred to as the master gun, for modifying the operation of said deflecting means to assure the guidance of the beam of said master gun with reference to said guiding strips and means for causing the beam of the gun other than said master gun, referred to as the slave gun, to be rapidly deflected vertically relative to the beam of said master gun, so that the beam of said slave gun may scan the three luminescent strips of said triplets in a sequence suitable for coordination with successive switching of color video signals.

Claim 29

A luminescent screen display tube according to claim 20 adapted for the reproduction of color television images in accordance with the method of horizontal scanning known as interlaced scanning, wherein the guiding strips are each associated with a plurality of luminescent color strips and only some of said strips are scanned by the beams at each half-field.

Claim 30

A luminescent screen display tube according to claim 20 in which each guide strip pair is disposed in predetermined relation to two triplets of luminescent color strips such that when said guide strip pair is scanned in one half frame one of said triplets will be scanned, and when said guide strip pair is scanned in the other half frame the other of said triplets will be scanned.