One-gun two-beam cathode ray tube

• US 4,371,808 A
• Filed: 11/24/1980
• Issued: 02/01/1983
• Est. Priority Date: 12/07/1979
• Status: Expired due to Term

• Current Assignee: Iwatsu Electric Company Limited
• Original Assignee: Iwatsu Electric Company Limited
• Inventors: Kaneko, Isamu, Urano, Tadao
• Primary Examiner(s): Anderson, Bruce C.
• Application Number:
  US06/209,484
• Time in Patent Office: 799 Days
• Field of Search: 313/411, 313/414, 313/426, 313/432, 313/429, 313/460, 315/13 R
• US Class Current: 313/411
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: H01J 29/46 Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement transit time tubes H01J23/00, H01J25/00; X-ray tubes H01J35/00; beam tubes for examining ions, e.g. electron or ion microscopes, or processing of objects or materials, e.g. electron or ion beam tubes H01J37/04; electron multipliers H01J43/04; handling of radiation or particles, e.g. focusing, deviating, not otherwise provided for G21K1/00
• CPC Class Codes: H01J 29/803 for post-acceleration or post-deflection, e.g. for colour switching
• CPC Class Codes: H01J 31/12 with luminescent screen

Abstract

The electron beam emanated by a single electron gun falls, after traversing two successive quadrupolar electron lenses, on a beam separator electrode having a pair of vertically spaced apertures formed therethrough for permitting the passage of fractions of the incident beam as two separate beams for dual image display. Subsequently deflected vertically by respective pairs of vertical deflection plates, the two display beams follow their trajectories to a target screen through a focus corrector device, a third quadrupolar electron lens, a pair of horizontal deflection plates, and a dome-shaped scan expansion mesh. Were it not for the focus corrector device, the spots of the display beams on the screen would differ in size according to whether they were deflected upwardly or downwardly by the vertical deflection plate pairs disposed respectively above and below the tube axis. Comprising four plates arranged in boxlike configuration with insulating gaps therebetween, the focus corrector device functions to compensate for spot size variations in the vertical direction.

Claims

1. A one-gun two-beam cathode ray tube comprising:

(a) an envelope having a target screen;

(b) an electron gun for producing an electron beam directed toward the target screen;

(c) a first quadrupolar electron lens disposed along the path of the beam for diverging the beam in a first direction and for converging the beam in a second direction, the first and the second directions being at right angles with each other;

(d) a second quadrupolar electron lens disposed along the path of the beam from the first electron lens for converging the beam in the first direction and for diverging the beam in the second direction;

(e) beam separator means disposed across the path of the beam from the second electron lens and defining a pair of apertures equidistantly spaced from, and aligned in the first direction with, the geometrical center of the cross section of the incident beam, whereby two separate fractions of the incident beam are admitted through the apertures to provide first and second display beams of smaller cross sectional size;

(f) a first pair of deflection plates for deflecting the first display beam from the beam separator means in the first direction;

(g) a second pair of deflection plates for deflecting the second display beam from the beam separator means in the first direction;

(h) focus corrector means disposed along the paths of the first and the second display beams from the first and the second pairs of deflection plates, the focus corrector means comprising first and second opposed pairs of electrodes which are arranged in generally boxlike configuration and which are separated from one another, the first opposed pair of electrodes being spaced from each other in the first direction and so positioned that the first and the second display beams pass the opposite sides of the midpoint between the first pair of electrodes, the second opposed pair of electrodes being spaced from each other in the second direction to an extent necessary for the passage of each display beam, the first pair of electrodes being set at a potential higher than the potential of the second pair of electrodes, whereby the first and the second display beams are diverged in the first direction to a greater extent as the display beams pass closer to the respective electrodes of the first pair;

(i) a third quadrupolar electron lens for diverging the first and the second display beams from the focus corrector means in the first direction and for converging the first and the second display beams in the second direction; and

(j) a third pair of deflection plates for deflecting the first and the second display beams from the third electron lens in the second direction.

2. The cathode ray tube as set forth in claim 1, further comprising means for independently adjusting the potentials of the first opposed pair of electrodes of the focus corrector means.

3. The cathode ray tube as set forth in claim 1 or 2, wherein the second pair of electrodes of the focus corrector means are set at a potential equal to the nondeflecting potential of the first and the second pairs of deflection plates.

4. The cathode ray tube as set forth in claim 1, further comprising a scan expansion mesh interposed between the third pair of deflection plates and the screen.

5. The cathode ray tube as set forth in claim 1, further comprising a pair of brightness control electrodes interposed between the electron gun and the first quadrupolar electron lens for controlling the relative brightnesses of the displays created by the first and the second display beams.