US 2823512 A
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Feb. 18, 1958 J. 0. LE VAN 2,823,512
LUMINOUS WATCH DIAL Filed Sept. 8, 1954 6 v .uues'o; u: ww
IIIIIIIII/IIIIIIIA Fl6.8 BY
ATTORNEY INVENIOR III United Eitates Patent LUMINOUS WATCH DIAL James Oliver Le Van, Lancaster, Pa., assignor to Hamilton Watch Company, Lancaster, Pa.
Application September 8, 1954, Serial No. 454,728
1 Claim. (CI. 58-50) This invention relates to a luminescent watch dial which has a phosphor composition which is bombarded by beta rays emanating from either moving or stationary parts adjacent the watch dial, and causing the phosphor portions to glow.
It is a further object of the present invention to present a decorative watch dial which in the darkness would be caused to glow adjacent the hands.
It is a still further object of the present invention to provide a phosphor coating on the watch dial minute track and to provide on a sweep second hand a beta ray emitting substance which will cause the phosphor track to glow brightly directly under the hand and at a diminishing intensity in back of the hand to provide a cometlike effect moving around the minute track of the watch.
It is a still further object of the present invention to provide a coating of beta ray emitting substance for the undersurface of the minute and hour hands and to coat the surface of the dial with a phosphor so that the hands will cause that portion of the dial directly below them to glow brightly and to cause the remainder of the dial to have a slight radiance.
The invention is illustrated in the accompanying drawing in which:
Figure 1 is a top plan view of a watch dial showing numerals and markers having a phosphor associated therewith and a pair of hands carrying a beta ray emitting substance.
Figure 2 is a section on line 2-2 of Figure 1.
Figure 3 is a section on line 33 of the minute hand, showing a method of limiting the radiated area.
Figure 4 is a plan view of a dial having a phosphor coated track and a beta ray emitting sweep second hand.
Figure 5 is a section on line 55 of Figure 4.
Figure 6 is a plan view of a dial having its surface coated with a phosphor and a pair of hands having its undersurface coated with a beta ray emitting substance, the dial surface covered with phosphors, and numerals or markers of solid non luminous material.
Figure 7 is a section on line 7-7 of Figure 6.
Figure 8 is a partial cross section of a watchcase, dial and crystal showing a beta ray emitting ring around the circumference of a phosphor coated dial for continuous radiation of the dial and marker phosphors.
Referring particularly to Figures 1, 2, and 3, a dial 12 has attached thereto numerals 13 and markers 14. The numerals are coated with a phosphor composition such as calcium or zinc sulphide, while the markers 14 have a hollow well which may be filled with the same substance. A minute hand 15 and an hour hand 16 is formed to provide a slight recess in the undersurface of the hand which may be filled with a beta ray emitting substance 17 such as nickel 63 or iron 55. The hour hand 16 is likewise formed and the passage of these hands in close proximity to and across the face of the dial will cause the beta rays to strike the phosphor coated surface of the numerals and the filled wells of the markers, giving off a glow which is sulficient to enable the user to see the numerals and ascertain the time in the dark.
Referring particularly to Figure 4, a decorative watch dial 18 is provided with a phosphor coated minute track 19 and a sweep second hand 2t having a head 21 formed similar to the hands 15 and 16 of Figure l which is filled with a small amount of beta ray emitting material. In its-rather rapid passage around the dial, the hand provides a comet like efiect as the track lights brilliantly directly under the head 21 and provides a light of diminishing intensity over a trailing arc of approximately A third form involving the use of the beta ray emitting substance and a glowing phosphor is shown in Figures 6 and '7, the dial 22 being coated with the phosphor as shown at 23 and the bottom of the hands 24 and 25 coated as at 26 with a beta ray emitting substance. With the applied numerals 27 uncoated the passage of the hands around the dial will cause a brilliant light directly under the hands showing the numerals silhouetted and a diminished glow over that portion of the dial not directly under the hands.
Figure 8 shows a watchcase 28 having a dial 29 and a crystal 30. Adjacent the bezel 31 and at the outer rim of the dial 29 is a ring 32. This ring is formed of a beta ray emitting substance such as nickel 63 and the surface of the dial 29 is coated as at 33 with a phosphor, the beta rays causing the outer rim of the dial to glow very distinctly while the center of the dial will have less glow but still capable of being distinguished in the dark.
What is claimed is:
In a watch, a dial having a phosphor coated minute track, a hand revolving in close proximity to the dial, the coating to be such as to glow for fifteen seconds after exposure to ray emanations, a beta ray emitting substance carried on the undersurface of said hand and directly above said minute track.
References Cited in the file of this patent UNITED STATES PATENTS 394,386 Nicholson Dec. 11, 1888 863,287 Kunz Aug. 13, 1907 2,403,316 Wallhausen July 2, 1946 FOREIGN PATENTS 232,944 Switzerland Sept. 16, 1944 271,166 Switzerland Jan. 3, 1951 OTHER REFERENCES Reviews of Modern Physics publication, vol. 16, No. 1 of January 1944, pp. 1, 2, 7 and 8.
General Electric Co. Research Lab. publication No. 1041 of June 1940, p. 148.