US5287038A
Expired / Lapsed
US
⏱️ 0.0 years remaining
High resolution electron gun
Assignee: L3 Technologies Inc
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Filing: 1992-05-14
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Granted: 1994-02-15
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Expires: 2012-05-14
Abstract
Abstract An improved resolution electron gun for a cathode ray tube(CRT) is provided having a cathode, a control grid and an anode. A positive voltage is applied to the anode for the purpose of drawing the electron beam from the cathod, which emits the electron beam along its principal axis. The control grid between the cathode and the anode has a modulating drive voltage to modulate the emitted beam. The anode and the grid are aligned along the principal axis of the cathode and are adjacent to one another. A limiting aperture is mounted along the principal axis to clip the beam and reduce its diameter. A screen is provided along the principal axis within the CRT to receive the projected beam. To obtain increased resolution, the modulating drive voltage is increased while the aperture size is decreased. More specifically, the modulating drive voltage is increased beyond 25% of a predetermined maximum cutoff value, and the limiting aperture permits less than 50% of beam current to transmit.
Inventors
- 👤 Robert A. Hagar
- 👤 Arthur J. Ingle
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 20:50
CPC Classifications
H; H01; H01J; H01J29/00; H01J29/46; H01J29/48; H01J29/488
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
222 words
An electron gun of a cathode ray tube to project an electron beam onto a screen of said cathode ray tube, said electron gun comprising: a cathode having an electron emitting surface, a first anode having a high positive voltage, and a control grid between said cathode and said first anode and aligned along an axis formed by said cathode and said first anode, intensity of said electron beam varying in response to a drive voltage applied to said control grid, said drive voltage being greater than 30% of a maximum cutoff voltage; a second anode located beyond said first anode and aligned along said axis, said second anode having a relatively high positive voltage to accelerate said electron beam, said voltage at said second anode being substantially higher than said voltage at said first anode; and a clipping aperture located within said anode aligned along said axis and receiving a centermost portion of said accelerated electron beam therethrough with an outer portion of said beam being shunted off, said clipping aperture allowing transmission of less than 50% of said beam and being less than 0.070 inches in diameter; wherein, said screen receives said centermost portion of said electron beam, and an increase in said drive voltage results in a corresponding decrease in line width of said beam measured at said screen.
Claim 2
Dependent Claim
222 words
An electron gun of a cathode ray tube to project an electron beam onto a screen of said cathode ray tube, said electron gun comprising: a cathode having an electron emitting surface, a first anode having a high positive voltage, and a control grid between said cathode and said first anode and aligned along an axis formed by said cathode and said first anode, intensity of said electron beam varying in response to a drive voltage applied to said control grid, said drive voltage being greater than 30% of a maximum cutoff voltage; a second anode located beyond said first anode and aligned along said axis, said second anode having a relatively high positive voltage to accelerate said electron beam, said voltage at said second anode being substantially higher than said voltage at said first anode; and a clipping aperture located within said anode aligned along said axis and receiving a centermost portion of said accelerated electron beam therethrough with an outer portion of said beam being shunted off, said clipping aperture allowing transmission of less than 50% of said beam and being less than 0.070 inches in diameter; wherein, said screen receives said centermost portion of said electron beam, and an increase in said drive voltage results in a corresponding decrease in line width of said beam measured at said screen.
Claim 3
Dependent Claim
15 words
The electron gun as defined in claim 1, wherein said electron beam is magnetically focused.
Claim 4
Dependent Claim
15 words
The electron gun as defined in claim 1, wherein said electron beam is electrostatically focused.
Claim 5
Dependent Claim
22 words
The electron gun as defined in claim 1, wherein the clipping aperture allows transmission of less than 25% of said electron beam.
Claim 6
Dependent Claim
21 words
The electron gun as defined in claim 1, wherein said drive voltage is greater than 35% of said maximum cutoff voltage.
Claim 7
Dependent Claim
22 words
The electron gun as defined in claim 5, wherein the clipping aperture allows transmission of less than 5% of said electron beam.
Claim 8
Dependent Claim
20 words
The electron gun as defined in claim 6, wherein drive voltage is greater than 40% of said maximum cutoff voltage.
Claim 9
Dependent Claim
21 words
The electron gun as defined in claim 7, wherein said drive voltage is greater than 45% of said maximum cutoff voltage.
Claim 10
Dependent Claim
175 words
An electron gun of a cathode ray tube to project an electron beam onto a screen of said cathode ray tube, said electron gun comprising: a cathode having an electron emitting surface, a first anode having a high positive voltage to draw said beam from said surface, and a means for controlling intensity of said electron beam in response to a drive voltage applied to said controlling means, said drive voltage being greater than 25% of a maximum cutoff voltage; a second anode located beyond said first anode and having a relatively high positive voltage to accelerate said electron beam, said voltage at said second anode being substantially higher than said voltage at said first anode; and a clipping means for receiving a centermost portion of said accelerated electron beam therethrough with an outer portion of said beam being shunted off, said clipping aperture allowing transmission of less than 50% of said beam; whereby, an increase of said drive voltage results in a corresponding decrease of line width of said beam measured at said screen.
Claim 11
Dependent Claim
175 words
An electron gun of a cathode ray tube to project an electron beam onto a screen of said cathode ray tube, said electron gun comprising: a cathode having an electron emitting surface, a first anode having a high positive voltage to draw said beam from said surface, and a means for controlling intensity of said electron beam in response to a drive voltage applied to said controlling means, said drive voltage being greater than 25% of a maximum cutoff voltage; a second anode located beyond said first anode and having a relatively high positive voltage to accelerate said electron beam, said voltage at said second anode being substantially higher than said voltage at said first anode; and a clipping means for receiving a centermost portion of said accelerated electron beam therethrough with an outer portion of said beam being shunted off, said clipping aperture allowing transmission of less than 50% of said beam; whereby, an increase of said drive voltage results in a corresponding decrease of line width of said beam measured at said screen.
Claim 12
Dependent Claim
38 words
The electron gun as defined in claim 9, wherein said controlling means further comprises a control grid disposed between said cathode and said first anode and aligned along an axis formed by said cathode and said first anode.
Claim 13
Dependent Claim
33 words
The electron gun as defined in claim 10, wherein said clipping means comprises a clipping aperture located within said second anode aligned along said axis and is less than 0.070 inches in diameter.
Claim 14
Dependent Claim
19 words
The electron gun as defined in claim 11, wherein said screen receives said centermost portion of said electron beam.
Claim 15
Dependent Claim
21 words
The electron gun as defined in claim 12, wherein said drive voltage comprises at least 40% of a maximum cutoff voltage.
Claim 16
Dependent Claim
27 words
The electron gun as defined in claim 9, wherein said maximum cutoff voltage is -60 volts and said drive voltage has a static value of -27 volts.
Claim 17
Independent Claim
167 words
A method for improving resolution of an electron beam projected by an electron gun onto a screen of a cathode ray tube, said electron gun comprising a cathode having an electron emitting surface, a first anode having a high positive voltage, and a control grid between said cathode and said first anode and aligned along an axis formed by said cathode and said first anode, intensity of said electron beam varying in response to a drive voltage applied to said control grid, the method comprising the steps of: passing a centermost portion of said electron beam through a clipping aperture which shunts off an outer portion of said beam, said clipping aperture allowing transmission of less than 50% of said beam, said clipping aperture being disposed within a second anode of said electron gun, said second anode having a voltage which is substantially higher than said voltage at said first anode; and increasing said drive voltage to a value greater than 25% of a maximum cutoff value.
Claim 18
Independent Claim
167 words
A method for improving resolution of an electron beam projected by an electron gun onto a screen of a cathode ray tube, said electron gun comprising a cathode having an electron emitting surface, a first anode having a high positive voltage, and a control grid between said cathode and said first anode and aligned along an axis formed by said cathode and said first anode, intensity of said electron beam varying in response to a drive voltage applied to said control grid, the method comprising the steps of: passing a centermost portion of said electron beam through a clipping aperture which shunts off an outer portion of said beam, said clipping aperture allowing transmission of less than 50% of said beam, said clipping aperture being disposed within a second anode of said electron gun, said second anode having a voltage which is substantially higher than said voltage at said first anode; and increasing said drive voltage to a value greater than 25% of a maximum cutoff value.
Claim 19
Dependent Claim
35 words
The method for improving resolution of an electron beam as defined in claim 15, wherein a size of said clipping aperture is selected to produce a negative sloping curve on a drive voltage-line width graph.
Claim 20
Dependent Claim
26 words
The method for improving resolution of an electron beam as defined in claim 16, wherein said clipping aperture has a diameter of smaller than 0.070 inch.
Claim 21
Dependent Claim
31 words
The method for improving resolution of an electron beam as defined in claim 15, wherein said drive voltage is increased to -27 volts and said maximum cutoff voltage is -60 volts.
Claim 22
Dependent Claim
21 words
The method for improving resolution of an electron beam as defined in claim 18, wherein said electron beam is magnetically focused
Claim 23
Dependent Claim
21 words
The method for improving resolution of an electron beam as defined in claim 18, wherein said electron beam is electrostatically focused.
References Cited (Backward Citations)
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1997-02-14 | 1997-08-16 | 1998-02-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-02-14 | 2001-08-16 | 2002-02-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-02-14 | 2005-08-16 | 2006-02-15 | $7700.00 | Window Closed / Lapsed |