1983 Volume 67 Issue 2 Pages 43-48
When the numerical display devices with 7 segments were minutely observed on segments constituting figures, the luminous unevenness within a segment and the luminous difference among each segments had been found.
If the luminous unevenness exists, visual impression is not only bad, but it is feared to cause misreading by decreasing the visibility of figures.
Then various tests were carried to investigate throughly the relations between the luminous unevenness and visibility.
The following results were given from the various tests.
(1) The permissible luminous difference was 1.4% to 4.2% among segments with rated luminance.
(2) The luminous ununiformity caused from figures have given the different visibility and also shown the more difference of the threshold to recognize figures.