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Wider than Wide-Angle TV Tube

Wireless World, February, 1957.
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A Wider than Wide-Angle television tube recently introduced by RCA in America makes one wonder if the flat 'picture-on-the-wall' display device will really be necessary after all. The tube is a 21-inch rectangular type (21EP4) and has a diagonal deflection angle as large as 110° (or a line scan angle of 106° as shown)! This has reduced the overa11 length by about 5= inches over comparable tubes with the same size of screen and 90° deflection angles. Another feature is a narrow neck diameter (l 1/8 in), which makes it possible to deflect the beam through the extra wide angle with only slightly more power than is required to scan a tube with a 90° angle. An electrostatic focusing system is incorporated for maintaining uniformity of focus over the whole screen. Other American tube manufacturers are following suit with the new angle.

This Mullard image published in 1959 shows a length comparison of 70°, 90° and 110° picture tubes.
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