Multiple beam electron discharge tube having bipotential acceleration and convergence electrode structure

In a multiple beam electron discharge tube having beam-producing means for producing plural electron beams directed along a central longitudinal axis and focusing means for focusing the electron beams toward a display screen, the improvement comprising:

• first array generating means receiving the plural electron beams generated by the beam-producing means to form a first array of electron beam crossovers having a first diameter;
• second array generating means including first and second partly overlapping cylindrical electrodes axially aligned with the central longitudinal axis and further including biasing means for applying a potential difference between the first and second electrodes to form a second array of electron beam crossovers having a second array diameter that differs from the first array diameter, the second array being focused toward the display surface by the focusing means which provides at the display surface a third array diameter that is proportional to the second array diameter;
• deflection means for scanning the electron beams across plural scan positions on the display surface;
• and
• compensating means communicating with the deflection means for generating a compensation signal corresponding to the scan position of the electron beams, the biasing means being responsive to the compensation signal to change the potential difference applied between the first and second electrodes, whereby the deflection means magnifies the electron beams by different amounts at different scan positions and the biasing means in response to the compensation signal compensates for the different magnifications and provides substantially uniform magnification at the different scan positions.