| 摘要 |
The invention relates to electron tubes, and most especially to beam-indexation display tubes. In order to increase the brightness of the display screen without impairing its resolution, the use is proposed, according to the invention, of an electron gun with two beams F1, F2 which are close together and undergo the same scanning. The beams are modulated independently of one another, so that each point can be illuminated in succession in the course of the same scanning cycle, by the two beams. The video signal applied to the second beam F2 is the same as that of the first beam but shifted temporally by a time corresponding to the overstepping of the distance which separates the points of impact of the beams on the screen (the distance measured along the scanning path). Thus, each point sees the same signal twice and the average brightness is increased by around 50% without bringing about impairment of the resolution as would occur if merely increasing the intensity emitted by a single beam. Preferably, in order to preclude phenomena of mutual repulsion of the beams F1 and F2, the beams are shifted such that, when one beam falls on a band of luminophores of colour R, G or B, the other falls on an opaque band N separating the bands of luminophores. <IMAGE>
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