Electric lamp and discharge devices – Cathode ray tube – Plural beam generating or control
Patent
1984-05-09
1986-09-16
Willis, Davis L.
Electric lamp and discharge devices
Cathode ray tube
Plural beam generating or control
313413, H01J 2950
Patent
active
046124748
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an in-line electron gun built in a color picture tube.
BACKGROUND ART
Generally, in a color picture tube comprising an in-line type electron gun from which three electron-beams are emitted into a plane, as shown in FIG. 1, a center beam 1a and side beams 1b, 1c pass through main lenses 2a, 2b, 2c, respectively, to be focussed. In order that the side beams 1b, 1c are converged to a point 3 at the center of the phosphor screen together with the center beam 1a, a beam convergence angle .theta. is given between each of the side beams 1b, 1c and the center beam 1a. Also, a self-convergence deflection magnetic field is provided so that the convergence of the three beams 1a, 1b, 1c is performed automatically even at deflection to the peripheries of the screen. In the picture tube system thus constructed, the beam convergence angle .theta. affects the beam convergence characteristics over the entire phosphor screen.
The beam convergence angle .theta. can be given by arranging three electron guns obliquely. But, in that method, the beam convergence angle .theta. is liable to be varied by assembly errors that occur when the three independent electron guns are integrated into an assembled gun. Generally, therefore, a unitized electron gun structure in which the relative displacement of the three electron beams is expected to be small is employed as shown in FIG. 2. A unitized electron gun is described in detail in Japanese Patent Publication No. 4905/77 and others. The center axes 6b, 6c of the side beam apertures 5b, 5c among the beam apertures 5a, 5b, 5c at the end of a focussing electrode 4 on the side of an anode electrode, and the center axes 9b, 9c of the side beam apertures 8b, 8c among the beam apertures 8a, 8b, 8c at the end of the anode electrode 7 on the side of the focussing electrode are displaced or offset to each other to obtain axially asymmetric side main lenses 10b, 10c, so that the side beams are electrostatically deflected by the beam convergence angle .theta..
Incidentally, in this unitized electron gun structure, the beam convergence angle .theta. is determined by the relative positions of the side beam apertures 5b, 5c of the focussing electrode 4 and the side beams apertures 8b, 8c of the anode electrode 7, and therefore a very severe manufacturing accuracy is required for the electrodes 4 and 7.
SUMMARY OF THE INVENTION
In the in-line type electron gun according to the present invention, the center axis common to the respective side beam apertures of the control electrode and the accelerating electrode is offset toward the tube axis from the center axis of the side beam aperture of the focussing electrode end surface on the side of the accelerating electrode, and at the same time, the center axis common to the respective side beam apertures at the opposite side surfaces of the focussing electrode and the anode electrode is offset toward the tube axis from the center axis common to the respective side beam apertures of the control electrode and the accelerating electrode.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram for explaining the convergence of three electron beams by a conventional in-line type electron gun,
FIG. 2 is a side sectional view showing the electrode configuration of a part of the same electron gun,
FIG. 3 is a side sectional view of an in-line type electron gun embodying the present invention, and
FIG. 4 is a diagram for explaining the convergence of three electron beams from the electron gun shown in FIG. 3.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
In the preferred embodiment of the invention shown in FIG. 3, three cathode electrodes 11a, 11b, 11c, arranged on a horizontal straight line, a control electrode 12, an accelerating electrode 13, a focussing electrode 14 and an anode electrode 15 make up a unitized in-line electron gun. A center beam aperture 16a and side beam apertures 16b, 16c of the control electrode 12 share common central axes 18a, 18b, 18c respectively with a center beam aperture
REFERENCES:
patent: 4291251 (1981-09-01), Bijma et al.
Ashizaki Shigeya
Muranishi Hideo
Natsuhara Masao
Sugahara Koichi
Matsushita Electronics Corporation
Oen William L.
Willis Davis L.
LandOfFree
In-line type electron gun does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with In-line type electron gun, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and In-line type electron gun will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1997338