![](../timeline/time011.jpg)
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.
![](../timeline/time011a.jpg)
This Mullard image published in 1959 shows a length comparison of 70°, 90° and 110° picture tubes.
|