Electron gun having extended field electrostatic focus lens

Claim 2

In combination: an electron gun constituting one of a delta or three-in-line gun cluster in the neck of a color cathode ray tube, said gun having a focus lens providing reduced spherical aberration for a given lens inner diameter, said focus lens comprising in closely spaced coaxial relationship: first and fifth end electrodes receiving substantially equal, relatively high applied potentials, second and fourth intermediate electrodes receiving substantially equal, relatively intermediate applied potentials, and a central third electrode receiving a relatively low applied potential; and means for supplying and applying said potentials to said electrodes.

Claim 3

The lens defined by claim 1 herein the applied potentials progress upwardly from said central electrode to said second and fourth intermediate electrodes and from said second and fourth electrodes to said first and fifth end electrodes in approximately geometrically progressive fashion.

Claim 4

The lens defined by claim 2 wherein the progression factor is approximately 2.

Claim 5

The lens defined by claim 1 wherein said relatively intermediate potential is in a range from about 30 to 70% of said relatively high potential, said relatively low potential is in a range from about 15 to 35% of said relatively high potential, and the progression from said relatively low potential to said Relatively intermediate potential to said relatively high potential is monotonic.

Claim 6

The lens defined by claim 1 wherein said central electrode has an axial length of about 0.5 to about 2.0 times its inner diameter.

Claim 7

The lens defined by claim 1 wherein all of said electrodes have an equal inner diameter.

Claim 8

The lens defined by claim 1 wherein each of said intermediate electrodes has axial dimension which is less than 1.5 times its inner diameter.

Claim 9

In combination: an electron gun constituting one of a delta or three-in-line gun cluster in the neck of a color cathode ray tube, said gun having a focus lens comprising first, second, third, fourth and fifth hollow cylindrical electrodes coaxially, consecutively and closely disposed; and means for supplying and applying to said first and fifth electrodes substantially equal, relatively high potentials, for supplying and applying to said second and fourth electrodes substantially equal relatively intermediate potentials, and for supplying and applying to said third electrode a relatively low potential, each of said five electrodes being axially dimensioned to establish in conjunction with said applied potentials: (i) an axially continuously active focusing region, and (ii) within a given lens diameter an axial potential distribution V0 having substantially reduced maximum values of V0II, where

Claim 10

In combination: an electron gun constituting one of a delta or three-in-line gun cluster in the neck of a color cathode ray tube, said gun having a focus lens comprising first, second, third, fourth and fifth hollow cylindrical electrodes coaxially, consecutively and closely disposed; and means for supplying and applying to said first and fifth electrodes substantially equal, relatively high potentials, for supplying and applying to said second and fourth electrodes substantially equal relatively intermediate potentials, and for supplying and applying to said third electrode a relatively low potential, each of said five electrodes being axially dimensioned to establish in conjunction with said applied potentials: (i) an axially continuously active focusing region, and (ii) within a given lens diameter an axial potential distribution V0 having substantially reduced maximum values of V0II, where

Claim 11

The lens as defined in claim 8 wherein said third electrode has an axial length of about 0.5 to 2.0 times its inner diameter.

Claim 12

The lens defined by claim 8 wherein each of said second and fourth electrodes has axial dimension which is less than 1.5 times its inner diameter.

Claim 13

In combination: an electron gun constituting one of a delta or three-in-line gun cluster in the neck of a color cathode ray tube, said gun having a focus lens comprising first, second, third, fourth and fifth hollow cylindrical electrodes coaxially, consecutively and closely disposed; means for supplying and applying to said first and fifth electrodes substantially equal, relatively high potentials, for supplying and applying to said second and fourth electrodes substantially equal relatively intermediate potentials, and for supplying and applying to said third electrode a relatively low potential, each of said five electrodes being axially dimensioned to establish in conjunction with said applied potentials: (i) an axially continuously active focusing region, and (ii) within a given lens diameter an axial potential distribution V0

Claim 14

In combination: an electron gun constituting one of a delta or three-in-line gun cluster in the neck of a color cathode ray tube, said gun having a focus lens comprising first, second, third, fourth and fifth hollow cylindrical electrodes coaxially, consecutively and closely disposed; means for supplying and applying to said first and fifth electrodes substantially equal, relatively high potentials, for supplying and applying to said second and fourth electrodes substantially equal relatively intermediate potentials, and for supplying and applying to said third electrode a relatively low potential, each of said five electrodes being axially dimensioned to establish in conjunction with said applied potentials: (i) an axially continuously active focusing region, and (ii) within a given lens diameter an axial potential distribution V0

Claim 15

The lens as defined by claim 11 wherein said third electrode has an axial length of about 0.5 to 2.0 times its inner diameter.

Claim 16

The lens defined by claim 11 wherein each of said second and fourth electrodes has axial dimension which is less than 1.5 times its inner diameter.

Claim 17

For use in a television cathode ray tube having associated therewith a power supply for developing discrete supply voltages, an electron gun for receiving supply voltages from the power supply to produce a focused beam of electrons, comprising: electron source means comprising cathode means and grid means; and focus lens means for receiving electrons from said electron source means and a predetermined pattern of supply voltages from the power supply to form an electron spot at a distance from said electron source, comprising: initial and final tubular end electrodes for receiving relatively high supply voltages, a low voltage tubular electrode located between said initial aNd final electrodes for receiving a relatively low supply voltage, and intermediate voltage electrode means between said low voltage electrode and at least one of said end electrodes for receiving a relatively intermediate supply voltage, said lens establishing an extended, axially continuously active focusing field which is substantially shielded from external field disturbances and establishing an axial potential distribution which decreases steadily in value from said initial end electrode to said low voltage electrode and increases steadily in value from said low voltage electrode to said final end electrode.

Claim 18

For use in a television cathode ray tube having associated therewith a power supply for developing discrete supply voltages, an electron gun for receiving supply voltages from the power supply to produce a focused beam of electrons, comprising: electron source means comprising cathode means and grid means; and focus lens means for receiving electrons from said electron source means and a predetermined pattern of supply voltages from the power supply to form an electron spot at a distance from said electron source, comprising: initial and final tubular end electrodes for receiving relatively high supply voltages, a low voltage tubular electrode located between said initial aNd final electrodes for receiving a relatively low supply voltage, and intermediate voltage electrode means between said low voltage electrode and at least one of said end electrodes for receiving a relatively intermediate supply voltage, said lens establishing an extended, axially continuously active focusing field which is substantially shielded from external field disturbances and establishing an axial potential distribution which decreases steadily in value from said initial end electrode to said low voltage electrode and increases steadily in value from said low voltage electrode to said final end electrode.

Claim 19

For use in a color television cathode ray tube having associated therewith a power supply for developing discrete supply voltages, an electron gun of the type constituting one of a delta or three-in-line gun cluster for receiving supply voltages from the power supply to produce a focused beam of electrons, comprising: electron source means comprising cathode means and grid means; and main focus lens means for receiving electrons from said electron source means and a predetermined pattern of supply voltages from the power supply to form an electron spot on the screen of the tube, comprising, in closely spaced relationship: first and fifth end electrodes for receiving substantially equal, relatively high supply voltages, second and fourth intermediate electrodes for receiving substantially equal, relatively intermediate supply voltages, and a central third electrode for receiving a relatively low supply voltage.

Claim 20

For use in a color television cathode ray tube having associated therewith a power supply for developing discrete supply voltages, an electron gun of the type constituting one of a delta or three-in-line gun cluster for receiving supply voltages from the power supply to produce a focused beam of electrons, comprising: electron source means comprising cathode means and grid means; and main focus lens means for receiving electrons from said electron source means and a predetermined pattern of supply voltages from the power supply to form an electron spot on the screen of the tube, comprising, in closely spaced relationship: first and fifth end electrodes for receiving substantially equal, relatively high supply voltages, second and fourth intermediate electrodes for receiving substantially equal, relatively intermediate supply voltages, and a central third electrode for receiving a relatively low supply voltage.

Claim 21

The lens defined by claim 15 wherein said relatively intermediate supply voltage is in a range from about 30 to 70% of said relatively high supply voltage, wherein said relatively low supply voltage is in the range from about 15 to 35% of said relatively high supply voltage but always lower than said relatively intermediate supply voltage, and wherein the progression from said relatively low supply voltage to said relatively intermediate supply voltage to said relatively high supply voltage is monotonic.

Claim 22

The lens defined by claim 15 wherein said central electrode has an axial length of about 0.5 to 2.0 times its inner diameter.

Claim 23

The lens defined by claim 15 wherein all of said electrodes have an equal inner diameter.

Claim 24

The lens defined by claim 15 wherein each of said intermediate electrodes has an axial dimension which is less than about 1.5 times its inner diameter.