Silhouette image on illuminated watch dial

An electroluminescent watch dial is provided with silhouette images on the dial. A transflective film covers an opaque image layer applied to a conventional electroluminescent watch dial. Timekeeping indicia are applied over the transflective film. The image is not seen in ambient light but is visible when the electroluminescent lamp is actuated.

BACKGROUND OF THE INVENTION 
This invention relates generally to improvements in illuminated dials for 
timepieces and more particularly to an improved electroluminescent lamp 
for a timepiece which provides a silhouette image when the lamp is lit. 
A prior art illuminated dial for a timepiece is disclosed in U.S. Pat. No. 
4,775,964 issued Oct. 4, 1988 to Alessio et al. and assigned to the 
Applicant's assignee. This prior art illuminated dial is shown in FIG. 1 
of the drawing, where the timepiece dial comprises the substrate on which 
electroluminescent (EL) layer elements are deposited. As shown in FIG. 1, 
the timepiece case 2 contains the watch hands 3, 4 mounted upon coaxial 
rotating stems 10, 11, connected to a watch movement 12. The case 2 
includes a transparent crystal 13 through which to observe the hands 3, 4 
and their position in relation to indicia 8, 9 on the dial 7. An 
electroluminescent drive circuit 14 supplies drive pulses via output leads 
15, serving as means for selectively illuminating the timepiece dial. Dial 
7 is mounted in case 2 by means of an insulating gasket 16, which 
electrically insulates it from case 2. 
Dial 7 comprises a transparent substrate 17 of Mylar.TM. film having an 
electrically conductive transparent layer 18 of indium tin oxide (ITO). A 
phosphor/binder electroluminescent layer 19 is applied to layer 18. The EL 
layer 19 comprises encapsulated phosphor particles in a polymerized 
suspension medium. A layer 20 of insulating dielectric material having 
reflective qualities, such as barium titanate, is deposited onto layer 19, 
and lastly a conductive electrode layer 21 of metallic aluminum is applied 
on top of layer 20 by vapor deposition. Timekeeping indicia 8, 9 are 
printed on the opposite side of substrate 17, and circumferentially spaced 
around the periphery of the dial 7. The aforementioned dial 7 is provided 
with a central aperture 22 for accommodating the rotatable stems 10, 11. 
The leads 15 are connected to electrodes 18, 21 at connection points 15a, 
15b respectively of dial 7, which is electrically floating with respect to 
the grounded watch case 2. 
The timekeeping indicia 8, 9 are visible in the daytime by reflection of 
the ambient light to the eye of the viewer. The indicia 8, 9 are also 
visible when the electroluminescent layer 19 is illuminated, since the 
indicia are opaque so as to block the light and appear as dark images on a 
lighted background. 
Another type of illuminated dial which is not selectively illuminated is 
described in U.S. Pat. No. 5,426,621 issued Jun. 20, 1995 to Akasaka. 
There a plate is coated with a phosphorescent maintaining luminous agent 
of rare-earth metal oxide and covered with a translucent member which may 
have timekeeping indicia on either its upper or lower surface. The indicia 
are visible against the background of the continuous phosphorescence 
beneath. Various methods of producing the timekeeping indicia are 
discussed, including photoetching patterns from a very thin metal plate. 
However there is no provision for selective display, and the time period 
of luminescence is limited. 
U.S. Pat. No. 4,747,086 issued May 24, 1988 to Shaw discloses a selectively 
illuminated fluorescent display. A thin mercury transflective coating is 
applied to the underside of the lens over the display, causing the lens to 
reflect ambient light and act as a mirror. When the display is actuated, 
conventional timekeeping indicia are viewable through the lens. 
It may be desirable to include images on the dial in addition to the 
timekeeping indicia. Such images might consist of designs, logos or 
pictures on the watch dial for advertising, entertainment or other 
purposes. However, the user of the timepiece may not wish the images to 
appear at all times. 
Accordingly, one object of the invention is to provide an improved 
timepiece dial which permits selective display of images on the dial. 
Another object of the invention is to provide an improved 
electroluminescent timepiece dial with an illuminated silhouette image. 
SUMMARY OF THE INVENTION 
Briefly stated the invention is practiced by providing a timepiece dial 
with an illuminated silhouette image, comprising an electroluminescent 
lamp adapted to serve as the dial for the timepiece and having an upper 
surface, means to selectively illuminate the lamp, a silhouette image 
comprising an opaque object covering a portion of the upper surface, a 
transflective layer covering both the upper surface and the silhouette 
image, and opaque timekeeping indicia disposed on the transflective layer.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to FIG. 2 of the drawing, the improvement of the present 
invention may be described. Substrate 17 and layers 18, 19, 20 and 21 are 
constructed in the same manner as previously described to provide an 
electroluminescent lamp, shown generally as 23, adapted to serve as a dial 
for a timepiece and having an upper surface 17a. 
In accordance with the present invention, one or more silhouette images 
designated as reference numeral 24 in FIG. 2 are applied to the upper 
surface 17a of substrate 17. Image 24 may be a design, logo, figure or 
image of any type comprising an opaque layer covering a portion of the 
upper surface. Silhouette image 24 may be applied by printing or painting 
on the upper surface, or by hot-stamping a foil, or it may be a separate 
pre-cut film of plastic or metal adhered to the upper surface 17a with an 
adhesive or by other suitable means. Preferably image 24 is an opaque ink 
of a color that will easily blend with the color of the electroluminescent 
lamp. 
Subsequently, a transflective layer 25 is applied over the entire surface, 
covering also the silhouette image 24. Transflective layer 25 is 
sufficiently thin so as not to block the light from the electroluminescent 
layer 19, but sufficiently thick so as to hide the opaque image from view 
and reflect ambient light in the daytime. A preferred material for the 
transflective layer is vinyl ink or paint, 6-9 microns (0.006-0.009 mm) in 
thickness. Alternatively, a thin sheet of vinyl with adhesive back, such 
as used on stickers and decals, may be used. Lastly, opaque timekeeping 
indicia 8, 9 are applied on top of the transflective layer 25 by printing, 
silk screening or attaching with adhesive. 
Referring now to FIGS. 3 and 4 of the drawing, top plan views are shown of 
the EL lamp 23 in the daytime and FIG. 4 when the EL lamp is illuminated. 
FIGS. 5 and 6 are simplified cross sectional views of EL lamp 23, wherein 
FIG. 5 corresponds to FIG. 3 in the daytime and FIG. 6 corresponds to FIG. 
4 when the EL lamp is selectively illuminated. 
Referring first to FIGS. 3 and 5, the transflective film or layer 25 
reflects ambient light. Since it covers the silhouette image 24, the image 
is not visible. However timekeeping indicia 8, 9 are visible, since light 
from them is also reflected. 
Referring to FIGS. 4 and 6, the transflective film 25 transmits light from 
the illuminated layer of the EL lamp to the eye as indicated by the arrow. 
However, light from the EL layer is blocked by the opaque image 24, as 
well as by the timekeeping indicia 8, 9. For this reason, both the 
silhouette image 24 and the timekeeping indicia 8, 9 will be visible at 
night. 
By means of the described invention, logos, designs or pictures on the 
timepiece dial may be invisible from view during the daylight hours, but 
selectively displayed as silhouette images when the user actuates the 
electroluminescent lamp. Although the lamp is ordinarily actuated in the 
nighttime, the images are also visible in subdued ambient light at any 
time of day when the EL lamp is actuated. 
While the invention has been described in connection with the preferred 
embodiment of an electroluminescent lamp, the invention is also applicable 
to other types of illuminated timepiece dials which may be selectively 
illuminated by a suitable light source. 
While there has been described what is considered to be the preferred 
embodiment of the invention, other modifications will occur to those 
skilled in the art, and it is desired to secure in the appended claims all 
such modifications as fall within the true spirit and scope of the 
invention.