EP0628983A1 - Electron gun for color image receiving tube - Google Patents
Electron gun for color image receiving tube Download PDFInfo
- Publication number
- EP0628983A1 EP0628983A1 EP94903111A EP94903111A EP0628983A1 EP 0628983 A1 EP0628983 A1 EP 0628983A1 EP 94903111 A EP94903111 A EP 94903111A EP 94903111 A EP94903111 A EP 94903111A EP 0628983 A1 EP0628983 A1 EP 0628983A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- electron gun
- electron
- electron beam
- electrode
- focusing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
- H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
- H01J29/58—Arrangements for focusing or reflecting ray or beam
- H01J29/62—Electrostatic lenses
- H01J29/626—Electrostatic lenses producing fields exhibiting periodic axial symmetry, e.g. multipolar fields
- H01J29/628—Electrostatic lenses producing fields exhibiting periodic axial symmetry, e.g. multipolar fields co-operating with or closely associated to an electron gun
Definitions
- This invention relates to an electron gun assembly for a color image receiving tube. Specifically, the invention relates to an electron gun assembly which prevents a lowering of the focusing characteristic of a color image receiving tube from being disturbed by aberrations caused by deviation of the centers of electron beams through holes of a main lens and by the occurrence of uneven magnetic field phenomena upon electron beams, such as deflection yoke, during the operation of the electron gun assembly.
- a color image receiving tube comprises a panel 11 on which a fluorescent film 12 is coated and a funnel 13 attached to the back of the panel 11 as shown in Fig. 1.
- an electron gun assembly 8 emitting thermion and a shadow mask 14 distinguishing colors are installed inside the image receiving tube.
- a deflection yoke 15 is mounted on the outer surface of the funnel 13 in order to deflect the electron beams.
- the electron gun assembly 8 is comprised of a cathode electrode heated and operated by a heater, a controlling electrode, a screen electrode, a focus electrode, an anode electrode and a shield cup which are placed in series in front of the cathode electrode.
- Each electrode is placed apart from each other at regular intervals and supported by bead glass in the shape of a pole or a plate.
- Each electrode has three electron beam passage holes.
- At least two electrostatic lenses are formed in the electron gun assembly; one is a pre-focus lens formed by the potential differences between the applied voltage of the screen electrode and the applied voltage of the focus electrode, and the other is a main lens formed by the potential differences between the applied voltage of the focus electrode and the applied voltage of the anode electrode.
- the pre-focus lens helps prevent the electron beam which emits toward the main lens from scattering, while the main lens converges the electron beam on the screen.
- Fig. 2 is a perspective view of the focus electrode used in the prior art for a electron gun assembly.
- the electrode body 1 three electron beam through holes a, b and c are arranged parallel to each other at regular intervals. If both external electron beams converge on the screen under each of the electron beam through holes of the focus electrode and the anode electrodes are not in accord with each other, an aberrations occur due to the distortion of the main lens, on the electron gun assembly of the prior art when both external electron beams are passing through the main lens, thereby creating a focusing characteristic of low quality.
- An object of this invention is to provide an electron gun assembly that prevents the lowering of the focusing characteristic of a color image receiving tube caused by the aberration of the electron beam which is in turn caused by the deviation of the center of electron beam through holes of the main lens and by uneven magnetic field phenomena such as a deflection yoke.
- the focusing characteristic on the entire screen since the central axis of the electron beam through holes in the focus electrode is accord with the central axis of the electron beam through holes in the anode electrode.
- Voltage of a magnitude greater than that applied to the focus electrode is applied to additional electrode members.
- additional electrode members are arranged in parallel with and between the paths of the electron beams in the focus electrode so that the electron beam is converged accurately on the screen.
- An embodiment of the invention has been illustrated as an electron gun assembly suitable to the separation type of cathode ray tubes, however this invention can be applied to electron gun assembles of other types of cathode ray tubes as well.
- Fig. 3 shows a perspective view of the focus electrode according to the present invention.
- focusing grooves 3 are formed on the focus electrode body 1 in parallel with the path of the electron beam and additional electrode members, each consisting of a flat thin plate, 31 and 32 which are inserted into the focusing grooves 3, respectively.
- Two focusing grooves 3 are made on the one surface of the focus electrode body either on the upper surface, or on the lower surface.
- the invention is not restricted to inserting additional electrode members 31 and 32 into the focusing grooves 3, nor is it restricted to their installation in the focus electrode.
- the additional electrode members 31 and 32 are preferably rectangular, thin plates of uniform length and breadth. However, they can be made in various shapes.
- the voltage Va is applied to the additional electrode members 31 and 32, respectively and this voltage Va is higher than the voltage Vb applied to the focus electrode body 1.
- the electron beam is affected by the electric field formed around the focus electrode as shown in Fig. 4.
- the additional electrode members cause the effect at the four electrode lenses which generates the astigmatism on the electron beam.
- Such additional electrode members generate an electric force which causes outside electron beams to move toward the central electron beam.
- the cross-sectional shape of the electron beam affected by the astigmatism passing through the main lens as shown in Fig. 5B is of greater uniformity than the cross-sectional shape of the electron beam in Fig. 5A.
- the electron beams show less aberration.
- an astigmatism resulting from an uneven magnetic field such as deflecting yoke is offset by the astigmatism caused by the additional electrode members, thereby remarkably improving the focusing characteristic around the screen.
- the application of dynamic focus voltage to the additional electrode members 31, 32 causes the focusing characteristics of the entire surface of the screen to improve remarkably thereby enabling an in-line type electron gun assembly having greater picture definition and high picture resolution.
- the present invention has improved the convergence and focusing characteristics of the electron beam by means of converging electron beams before their passage through the main lens.
- the present invention has enhanced the focusing characteristic of the electron gun assembly.
Landscapes
- Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
- Video Image Reproduction Devices For Color Tv Systems (AREA)
Abstract
The focusing characteristic of this electron gun is not impaired by the aberration caused by the deviation of the centers of the holes on both sides of the main lens, through which the electron beams are passed, and the astigmatism of the electron beams due to the uneven magnetic field such as of a deflecting yoke when the electron gun is in operation. In the focusing electrode (1) of the electron gun, a plurality of focusing grooves are formed in parallel with the direction in which the electron beams are passed. A plurality of additional electrode members, each consisting of a flat thin plate, are inserted into the focusing grooves, respectively.
Description
- This invention relates to an electron gun assembly for a color image receiving tube. Specifically, the invention relates to an electron gun assembly which prevents a lowering of the focusing characteristic of a color image receiving tube from being disturbed by aberrations caused by deviation of the centers of electron beams through holes of a main lens and by the occurrence of uneven magnetic field phenomena upon electron beams, such as deflection yoke, during the operation of the electron gun assembly.
- Generally, a color image receiving tube comprises a
panel 11 on which afluorescent film 12 is coated and afunnel 13 attached to the back of thepanel 11 as shown in Fig. 1. Inside the image receiving tube, anelectron gun assembly 8 emitting thermion and ashadow mask 14 distinguishing colors are installed. Adeflection yoke 15 is mounted on the outer surface of thefunnel 13 in order to deflect the electron beams. - The
electron gun assembly 8 is comprised of a cathode electrode heated and operated by a heater, a controlling electrode, a screen electrode, a focus electrode, an anode electrode and a shield cup which are placed in series in front of the cathode electrode. - Each electrode is placed apart from each other at regular intervals and supported by bead glass in the shape of a pole or a plate. Each electrode has three electron beam passage holes.
- Further, at least two electrostatic lenses are formed in the electron gun assembly; one is a pre-focus lens formed by the potential differences between the applied voltage of the screen electrode and the applied voltage of the focus electrode, and the other is a main lens formed by the potential differences between the applied voltage of the focus electrode and the applied voltage of the anode electrode. The pre-focus lens helps prevent the electron beam which emits toward the main lens from scattering, while the main lens converges the electron beam on the screen.
- If the central axis of the electron beam does not impact upon the center axis of the main lens, a halo phenomena results at the beam spots on the screen and the resolution of the color image receiving tube diminishes.
- Fig. 2 is a perspective view of the focus electrode used in the prior art for a electron gun assembly. In the electrode body 1, three electron beam through holes a, b and c are arranged parallel to each other at regular intervals. If both external electron beams converge on the screen under each of the electron beam through holes of the focus electrode and the anode electrodes are not in accord with each other, an aberrations occur due to the distortion of the main lens, on the electron gun assembly of the prior art when both external electron beams are passing through the main lens, thereby creating a focusing characteristic of low quality.
- An object of this invention is to provide an electron gun assembly that prevents the lowering of the focusing characteristic of a color image receiving tube caused by the aberration of the electron beam which is in turn caused by the deviation of the center of electron beam through holes of the main lens and by uneven magnetic field phenomena such as a deflection yoke.
- To achieve the electron gun assembly for a color image receiving tube according to the present invention can be improved the focusing characteristic on the entire screen since the central axis of the electron beam through holes in the focus electrode is accord with the central axis of the electron beam through holes in the anode electrode. Voltage of a magnitude greater than that applied to the focus electrode is applied to additional electrode members. Such additional electrode members are arranged in parallel with and between the paths of the electron beams in the focus electrode so that the electron beam is converged accurately on the screen.
-
- Fig. 1 is a side view of a conventional color image receiving tube.
- Fig. 2 is a perspective view of a focus electrode according to the prior art.
- Fig. 3 is a perspective view of a focus electrode according to the present invention.
- Fig. 4 shows distribution of electric field around the A-A line cross section of Fig. 3.
- Fig. 5A shows the cross sections of the electron beam passing through the main lens of the prior art.
- Fig. 5B shows the cross sections of the electron beam passing through the main lens of the invention .
- An embodiment of the invention has been described with reference to the accompanying drawings.
- An embodiment of the invention has been illustrated as an electron gun assembly suitable to the separation type of cathode ray tubes, however this invention can be applied to electron gun assembles of other types of cathode ray tubes as well.
- Fig. 3 shows a perspective view of the focus electrode according to the present invention. In order to enhance the focusing characteristic of the electron beam, focusing
grooves 3 are formed on the focus electrode body 1 in parallel with the path of the electron beam and additional electrode members, each consisting of a flat thin plate, 31 and 32 which are inserted into thefocusing grooves 3, respectively. - Two focusing
grooves 3 are made on the one surface of the focus electrode body either on the upper surface, or on the lower surface. The invention is not restricted to insertingadditional electrode members grooves 3, nor is it restricted to their installation in the focus electrode. - The
additional electrode members - The voltage Va is applied to the
additional electrode members - Accordingly, when the electron gun assembly is operated, the electron beam is affected by the electric field formed around the focus electrode as shown in Fig. 4.
- The additional electrode members cause the effect at the four electrode lenses which generates the astigmatism on the electron beam. Such additional electrode members generate an electric force which causes outside electron beams to move toward the central electron beam.
- Therefore, since both outside electron beams converge before they pass through the main lens, the cross-sectional shape of the electron beam affected by the astigmatism passing through the main lens as shown in Fig. 5B is of greater uniformity than the cross-sectional shape of the electron beam in Fig. 5A. As a result, the electron beams show less aberration.
- Further, an astigmatism resulting from an uneven magnetic field such as deflecting yoke is offset by the astigmatism caused by the additional electrode members, thereby remarkably improving the focusing characteristic around the screen.
- Accordingly, the application of dynamic focus voltage to the
additional electrode members - As described above, the present invention has improved the convergence and focusing characteristics of the electron beam by means of converging electron beams before their passage through the main lens. Using plate electrodes to correct the deviational errors of the electron beam caused by deflection yokes, the present invention has enhanced the focusing characteristic of the electron gun assembly.
Claims (1)
1. An in-line type electron gun assembly for a color image receiving picture tube comprised of a plurality of electrodes characterized in that additional electrode members 31, 32 are inserted parallel to the path of electron beam and between electron beam paths in the focus electrode.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR92028105U KR950003539Y1 (en) | 1992-12-31 | 1992-12-31 | Electron gun for color tv |
KR1992281U | 1992-12-31 | ||
PCT/KR1993/000118 WO1994016457A1 (en) | 1992-12-31 | 1993-12-28 | Electron gun for color image receiving tube |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0628983A1 true EP0628983A1 (en) | 1994-12-14 |
EP0628983A4 EP0628983A4 (en) | 1995-06-07 |
Family
ID=26629475
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP94903111A Withdrawn EP0628983A4 (en) | 1992-12-31 | 1993-12-28 | Electron gun for color image receiving tube. |
Country Status (1)
Country | Link |
---|---|
EP (1) | EP0628983A4 (en) |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4208610A (en) * | 1978-06-09 | 1980-06-17 | Zenith Radio Corporation | Television picture tubes having an electron gun with aperture electrode shielding means |
JPS59171434A (en) * | 1983-03-18 | 1984-09-27 | Hitachi Ltd | Electron gun structure for color picture tube |
US4498026A (en) * | 1982-02-03 | 1985-02-05 | Hitachi, Ltd. | Electron gun for color picture tube |
DE3614700A1 (en) * | 1985-04-30 | 1986-11-06 | Hitachi, Ltd., Tokio/Tokyo | CATHODE RAY TUBE |
JPS61264642A (en) * | 1985-05-20 | 1986-11-22 | Matsushita Electronics Corp | Inline type electron gun |
EP0241218A2 (en) * | 1986-04-03 | 1987-10-14 | Mitsubishi Denki Kabushiki Kaisha | Cathode ray tube apparatus |
-
1993
- 1993-12-28 EP EP94903111A patent/EP0628983A4/en not_active Withdrawn
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4208610A (en) * | 1978-06-09 | 1980-06-17 | Zenith Radio Corporation | Television picture tubes having an electron gun with aperture electrode shielding means |
US4498026A (en) * | 1982-02-03 | 1985-02-05 | Hitachi, Ltd. | Electron gun for color picture tube |
JPS59171434A (en) * | 1983-03-18 | 1984-09-27 | Hitachi Ltd | Electron gun structure for color picture tube |
DE3614700A1 (en) * | 1985-04-30 | 1986-11-06 | Hitachi, Ltd., Tokio/Tokyo | CATHODE RAY TUBE |
JPS61264642A (en) * | 1985-05-20 | 1986-11-22 | Matsushita Electronics Corp | Inline type electron gun |
EP0241218A2 (en) * | 1986-04-03 | 1987-10-14 | Mitsubishi Denki Kabushiki Kaisha | Cathode ray tube apparatus |
Non-Patent Citations (3)
Title |
---|
PATENT ABSTRACTS OF JAPAN vol. 009 no. 027 (E-294) ,6 February 1985 & JP-A-59 171434 (HITACHI SEISAKUSHO KK) 27 September 1984, * |
PATENT ABSTRACTS OF JAPAN vol. 011 no. 117 (E-498) ,11 April 1987 & JP-A-61 264642 (MATSUSHITA ELECTRONICS CORP) 22 November 1986, * |
See also references of WO9416457A1 * |
Also Published As
Publication number | Publication date |
---|---|
EP0628983A4 (en) | 1995-06-07 |
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