Methods and apparatus for post-assembly custom fine-tuning of an electron beam characteristic in a cathode ray imaging tube

Claim 3

The method in accordance with claim 1, said removal step comprising selectively operating a laser disposed exteriorly of the tube so as to burn away with the laser, through the sealed envelope of the tube, the resistive material in at least a portion of said region.

Claim 4

The method in accordance with claim 1, further comprising: operating the tube, while applying said voltage difference across said region of resistive material, so as to cause the electron beam to produce an image on the screen; examining the image produced on the screen; and selectively removing the resistive material in at least a portion of said region on the basis of said examination of the image produced on the screen so as to adjust said image for imparting the predetermined cross-sectional shape to the beam by selectively varying the positionally-varying electrostatic field generated by the voltage difference applied across said region of resistive material.

Claim 5

The method in accordance with claim 1, wherein the substantially continuous region of electrically resistive material is deposited o a substrate disposed within the interior of the tube.

Claim 6

The method in accordance with claim 4, wherein the substrate is the tube envelope.

Claim 7

The method in accordance with claim 1, wherein the tube envelope has a neck disposed remote from the imaging screen and through which the electron beam operatively passes to produce an image on the screen, the substantially continuous region of electrically resistive material being deposited proximate the neck of the tube envelope.

Claim 8

The method in accordance with claim 6, wherein the electrically resistive material is deposited on the tube envelope.

Claim 9

The method in accordance with claim 1, wherein the electrically resistive material is deposited substantially in the form of a cylinder through which the beam operatively passes in the operation of the tube.

Claim 10

The method in accordance with claim 6, wherein the electrically resistive material is deposited substantially in the form of a cylinder through which the beam operatively passes in the operation of the tube.

Claim 11

The method in accordance with claim 9, wherein the electrically resistive material is deposited on the envelope of the tube.

Claim 12

The method in accordance with claim 1, wherein said removing step further comprises selectively removing resistive material from said region so as to produce at least an area of said region having a substantially constant voltage within said area and correspondingly produce in said electrostatic field at least an area having a substantially constant electrostatic field.

Claim 13

The method in accordance with claim 1, wherein said resistive material is nichrome.

Claim 14

The method in accordance with claim 1, wherein said resistive material is a ceramic conductive material.

Claim 15

The method in accordance with claim 1, wherein said electrically resistive material is deposited within the tube so as to provide a substantially uniform resistance throughout said region.

Claim 16

The method in accordance with claim 1, wherein said depositing step further comprises depositing at least two areas of conductive material at spaced apart locations of said region, said voltage difference being applied to said region at said two areas of conductive material to produce a voltage gradient across said region and thereby generate said positionally-varying electrostatic field.

Claim 17

An electrostatic lens operable for focusing an electron beam on a focusing screen in a sealed envelope cathode ray tube, comprising: a lens element having an axially-defined substantially central opening through which the electron beam passes and to which an electrical potential is operatively applied; a substantially continuous region on said lens element formed of an electrically resistive material and providing a voltage gradient across said region to generate a substantially uniformly positionally-varying electrostatic field which operates on the electron beam as the beam passes through said lens element opening; said region having at least a discontinuity lacking said resistive material so as to create a nonuniformity in said substantially uniformly positionally-varying electrostatic field; said discontinuity being defined with a configuration and at a location of said region predeterminately selected in accordance with the operating characteristics of the particular tube by operating the tube to produce an image on the screen, examining the image, and defining in accordance with said examination of the image a suitable configuration and location for said discontinuity by which the cross-sectional shape of the electron beam is adjusted by the electrostatic field as the beam passes through said lens opening to attain a predetermined cross-sectional shape of the beam, whereby said discontinuity provides compensation for tube-to-tube beam focus-affecting variations in the operating characteristics of the tube so as to assure attainment of the predetermined cross-sectional shape to the beam in each particular tube.

Claim 18

An electrostatic lens operable for focusing an electron beam on a focusing screen in a sealed envelope cathode ray tube, comprising: a lens element having an axially-defined substantially central opening through which the electron beam passes and to which an electrical potential is operatively applied; a substantially continuous region on said lens element formed of an electrically resistive material and providing a voltage gradient across said region to generate a substantially uniformly positionally-varying electrostatic field which operates on the electron beam as the beam passes through said lens element opening; said region having at least a discontinuity lacking said resistive material so as to create a nonuniformity in said substantially uniformly positionally-varying electrostatic field; said discontinuity being defined with a configuration and at a location of said region predeterminately selected in accordance with the operating characteristics of the particular tube by operating the tube to produce an image on the screen, examining the image, and defining in accordance with said examination of the image a suitable configuration and location for said discontinuity by which the cross-sectional shape of the electron beam is adjusted by the electrostatic field as the beam passes through said lens opening to attain a predetermined cross-sectional shape of the beam, whereby said discontinuity provides compensation for tube-to-tube beam focus-affecting variations in the operating characteristics of the tube so as to assure attainment of the predetermined cross-sectional shape to the beam in each particular tube.

Claim 19

An electrostatic lens in accordance with claim 16, wherein said substantially continuous region of resistive material is in the form of a cylinder through which the electron beam passes.

Claim 20

An electrostatic lens in accordance with claim 16, wherein said region of resistive material is formed on the tube envelope.

Claim 21

An electrostatic lens in accordance with claim 17, wherein said region of resistive material is formed on the tube envelope.

Claim 22

An electrostatic lens in accordance with claim 16, wherein said region of resistive material is depositedon a substantially nonconductive substrate.

Claim 23

An electrostatic lens in accordance with claim 16, wherein said discontinuity is defined after sealing of the tube envelope.

Claim 24

An electrostatic lens in accordance with claim 16, wherein the tube envelope has a neck disposed remote from the imaging screen and through which the electron beam passes to produce an image on the screen, the substantially continuous region of resistive material being disposed proximate the neck of the tube envelope.

Claim 25

An electrostatic lens in accordance with claim 16, wherein said discontinuity defines an area of resistive material having a substantially constant voltage within said area for generating a corresponding area of said field having a substantially constant electrostatic field.

Claim 26

An electrostatic lens in accordance with claim 16, wherein said resistive material has a substantially uniform resistance throughout said region so as to provide a substantially uniform voltage gradient across said region.

Claim 27

An electrostatic lens in accordance with claim 16, wherein said resistive material is one of nichrome and a ceramic conductive material.

Claim 30

A method in accordance with claim 26, further comprising operating the cathode ray tube to produce a beam-generated image on the screen, examining said characteristic of the beam in the image generated on the screen, and controlling said removing of at least one selected portion of said region of resistive material in accordance with said examination of the beam characteristic to thereby adjust the electrostatic field for optimizing said beam characteristic.

Claim 31

A method in accordance with claim 26, wherein the field-generating device controls the focus of the electron beam on the imaging screen.

Claim 32

A method in accordance with claim 28, wherein said characteristic is the cross-sectional shape of the electron beam.

Claim 33

A method in accordance with claim 26, wherein said characteristic is the cross-sectional shape of the electron beam.

Claim 34

A method in accordance with claim 26, wherein the support on which the resistive material is deposited is the tube envelope.

Claim 35

A method in accordance with claim 26, wherein the tube envelope has a neck disposed remote from the imaging screen and through which the electron beam operatively passes to produce an image on the screen, the region of electrically resistive material being deposited proximate the neck of the tube envelope.

Claim 36

A method in accordance with claim 32, wherein the support on which the resistive material is deposited is the tube envelope.

Claim 37

A method in accordance with claim 26, wherein the electrically resistive material is deposited substantially in the form of a cylinder through which the beam operatively passes in the operation of the tube.

Claim 38

A method in accordance with claim 31, wherein the electrically resistive material is deposited substantially in the form of a cylinder through which the beam operatively passes in the operation of the tube.

Claim 39

A method in accordance with claim 26, wherein said electrostatic field generated by said voltage difference is positionally-varying field, and said removing step further comprises selectively removing resistive material from said region so as to produce at least an area of said region having a substantially constant voltage within said area and correspondingly produce at least an area of said field having a substantially constant electrostatic field.

Claim 40

A method in accordance with claim 26, wherein said electrostatic field generated by said voltage difference is a substantially uniformly positionally-varying field, and said removing step further comprises selectively removing resistive material from said region so as to produce at least an area of said region having a substantially constant voltage within said area and correspondingly produce at least an area of said field having a substantially constant electrostatic field.

Claim 41

A method in accordance with claim 26, wherein said electrically resistive material is deposited within the tube so as to provide a substantially uniform resistance throughout said region.

Claim 42

A method in accordance with claim 26, wherein said resistive material is nichrome.

Claim 43

A method in accordance with claim 26, wherein said resistive material is a ceramic conductive material.

Claim 44

A method in accordance with claim 26, wherein said depositing step further comprises depositing at least two areas of conductive material at spaced apart locations of said region, said voltage difference being applied to said region at said two areas of conductive material to produce a voltage gradient across said region and thereby generate said positionally-varying electrostatic field.