The invention relates to a display device for a wristwatch having a luminescent surface for the background illumination of a display element.
It is known from the prior art for digital displays for dates, days of the week and/or chronometer functions to be provided with numbers, in which case an analog movement mechanism simultaneously displays hours, minutes and seconds using hands.
Such timepieces have the advantage that they can be configured purely mechanically and thus do not require any energy source such as a battery and/or a solar cell in order to function. The problem with these analog timepieces, then, is to render the display visible in the dark. For this purpose, it is possible to provide a battery or rechargeable storage battery, by means of which a luminous unit is supplied with energy. U.S. Pat. No. 6,208,591 utilizes a luminescent layer which is arranged in and beneath the then transparent face. This luminescent layer illuminates the hands of the timepiece from behind. However, it is thus not possible to render additional digital information of the timepiece readable in the dark.
It was also known to apply luminescent materials to the hands in order for the latter to be luminous in the dark. The application of these materials to numbers which indicate the digital time units, however, is associated with two significant problems. On the one hand, the application of these materials results in these digital time displays becoming considerably thicker. Furthermore, such displays only appear in a window during the corresponding time unit and are otherwise covered by the face, with the result that they are not recharged to a sufficient extent.
There is no question of using radioactive products for sales of timepieces in the civilian sector.
Wristwatches, finally, are often provided exclusively with a digital display of time units. These watches are usually with an LCD display. Such watches require a power source.
Taking this prior art as the departure point, the object of the invention is to configure a display device of the type mentioned in the introduction such that the digital time display is also visible in the dark.
This object is achieved according to the invention, for a display device for a wristwatch of the type mentioned in the introduction, by the features of claim 1.
Since it is exclusively the region behind the window in the face which is coated with the luminescent material, it can be ensured that this region is constantly recharged when the watch is worn, provided the watch is not covered by clothing. The numbers which appear in the window either are introduced in a transparent disk or consist essentially of a punched-out material, the parts of which are connected to one another merely via thin connecting crosspieces. This has the advantage that it is only in the region of this window that account has to be taken of the considerable thickness of the luminescent material, but the number disks, which bear the digital time-display units, may be of very thin configuration, in the customary manner.
Further advantageous embodiments are characterized in the subclaims.
The invention will now be described by way of example using exemplary embodiments and with reference to the attached drawings, in which:
The hands 2, 3 and 4 and also 14 in the exemplary embodiments according to
The disk 21 which is illustrated here by way of example comprises a region 23 of transparent material which has arranged in its interior 25 or on its surface at the top 24 or bottom 26, preferably at the top 24, an opaque display element, in this case the number “8”, which is designated 22. Arranged beneath this rotating disk 21, opposite the window 5, is a disk 19 which is fixed in relation to the housing of the watch and, in its central region, is provided with luminescent material, designated 29 here. The surface coated by the luminescent material 29 is advantageously somewhat larger than the opening of the window 5, with the result that even slanting incident light through the window 5, this light passing through the disk 21, illuminates border regions of the luminescent material and thus also charges the same.
The disk 21 is advantageously highly transparent and has a slightly diffusing action on its underside 26, with the result that, irrespective of the region covered by the display element 22, those sub-regions of the surface 29 which are located directly beneath the display element 22 also receive light. It is thus the case with each type of display, i.e. with each date and/or each day of the week and/or the chronometer numbers, that most of the surface 29 in each case is illuminated, with the result that, when it is light, the (dark) display element 22 can be read against the light background and, in the dark, it is visible as a negative in relation to the light-emitting element 29.
It is thus possible for the light passing in through the window 5 to act on the luminescent surface 29 without obstruction, with the exception of the region covered by the display element 32. All the crosspieces 33 and/or the carrier structure 34 may be of transparent configuration and only the display element 32 is opaque, or is made of the same transparent material as the crosspieces 33 but coated with an opaque material.
Both the cases mentioned in
Number | Date | Country | Kind |
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2073/01 | Nov 2001 | CH | national |
Filing Document | Filing Date | Country | Kind |
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PCT/CH02/00592 | 11/4/2002 | WO |