Display screen with a scan button icon

FIG. 1 shows a front view of a portion of a display screen with the scan button icon of the claimed design. The portion of the display screen shown, which has been isolated and enlarged for clarity of disclosure, corresponds to a portion of a smartphone display screen as shown in FIG. 2 ; and,

FIG. 2 shows a front view of a display screen of a smart phone with the scan button icon of the claimed design.

The broken lines in FIG. 1 illustrate an enlarged, isolated portion of the display screen shown in FIG. 2 . The sharp-cornered, vertical-oriented broken-line rectangle shown in FIG. 2 illustrates the perimeter of the display screen of a smart phone. The broken lines outside this perimeter illustrate portions of the smart phone. The broken lines within this perimeter illustrate portions of a graphical user interface. The broken lines form no part of the claimed design.