Abstract:
A date display assembly for a timepiece, wherein the timepiece comprises a casing, an hour wheel that is rotationally engaged with a meshing wheel, and a display window for displaying a date, the date display assembly comprising an outer date ring having a plurality of digits thereon and aligned in the casing such that each of the plurality of digits is appearable in the display window; an inner date ring having a plurality of digits thereon and also aligned in the casing such that each of the plurality of digits is appearable in the display window; a date wheel, rotatably engageable with the meshing wheel, for driving the outer date ring in a first direction; and an inner date ring driving wheel, rotatably engageable with the outer date ring, for driving the inner date ring in a direction opposite the first direction.

Description:
BACKGROUND OF THE INVENTION 
   This invention relates generally to timepieces having a date display, and more particularly, to an improved assembly that is able to facilitate viewing of the date because the date display can be made larger than in conventional timepieces with date displays. 
   Providing a date window in a timepiece, such as in an analog or chronograph watch has been known for many years, and accordingly, the basic mechanism, gear and dial movements used in connection therewith are quite old in the art. 
   However, certain styles of watches are designed to be small, such as those designed for a small wrist, such as in certain ladies style watches. For example, certain watch styles are designed both in a large version for a man, and a somewhat smaller although identical version for a woman. Unfortunately, as the watch casing size decreases, the circumference of the date ring (and corresponding size of the numbers thereon) needs to decrease, thus resulting in a calendar date feature that may be considered harder to see. 
   Accordingly, it would be desirable to provide a way to increase the size of the date that is viewed through the display. One way, of course, would be to either increase the size of the numbers on the date ring or the space available to display the date. While these may be satisfactory in some instances, they are less satisfactory than desired. 
   A more promising way to achieve satisfactory date display sizing is to utilize two date rings, one of which having printed thereon numbers from 0–9, while the other having the digits 1–3 printed thereon. While one such example can be found in DE 41 27 825, a more relevant construction has been proposed and was incorporated in a watch hereinafter believed to be sold under the name RONDA. Three figures showing the RONDA construction are set forth in  FIGS. 7 and 8 . However, for various reasons, it has been determined that such a constructions is less than desirable. For example, while  FIG. 7  simply illustrates the outer date ring  100  and the inner date ring  110 .  FIG. 8  more particularly illustrates the mechanical workings thereof. 
   Specifically,  FIG. 8  illustrates how an outer ring driving wheel  120  can be positioned to drive inner date ring  110 . In turn, outer date ring  100  can be seen to rotate an intermediate wheel  120 , by the meshing of teeth  105  on outer date ring  100  and corresponding teeth  125  and formed valleys on the outer surface of intermediate wheel  120 . Therefore, it can be readily seen that each daily rotation of outer date ring  100  causes a corresponding rotation of intermediate wheel  120 . 
   Furthermore, on intermediate wheel  120  is a finger  130 , which has been highlighted for the convenience of the reader. Also readily viewable is a center wheel  140  (with a  110 . Accordingly, the rotation of centerwheel  140  correspondingly rotates inner date ring  110 . 
   The rotation of centerwheel  140  is caused by the engagement of finger  130  with the plurality of teeth  145 . This engagement can be seen to occur once every 10 th  day. This is, each day outer date ring  100  can be seen to rotate about 360/20 degrees (taking into account that the outer ring digits are repeated only once). Likewise, each day, intermediate wheel rotates about 360/10 degrees, with finger  130  only engaging centerwheel  140  only once every 10 th  day. 
   This construction gives rise to at least one significant perceived disadvantage. 
   Specifically, it can be seen that if intermediate wheel  120  is positioned with finger  130  in any of the 9 positions other than the only one which will cause the proper advancing of centerwheel  140  and thus inter date ring  110 , it is likely that inner date ring  110  may be caused to advance when the “one” digit in the window (not show) is other than the numeral “9”. This result may be caused due to a misalignment of intermediate wheel  120  during manufacture/repair of the watch itself, or may occur for example, if there is a meshing misalignment between teeth  125 , for example (i.e. one of the teeth  105  may be damaged). Other easily envisioned misalignments are possible. 
   However, what is readily apparent is that the precision orientation of finger  130  with respect to the positioning of outer ring and/or the inner ring will be destroyed, thereby resulting in a permanent error in date advancement. For example, in one misalignment, the date will permanently advance for “08” to “19,” “18” to “29” and “28” to “09). Such a result is not readily fixable by the user without taking the entire watch apart. 
   Therefore, further developments to improve the size of the data displayed in the date window by utilizing two date rings are desirous, and are achieved by the present invention. 
   SUMMARY OF THE PRESENT INVENTION 
   Generally speaking, it is an object to provide an improved date display assembly for a timepiece. 
   It is thus another object to provide a date display assembly that be incorporated into a small watch causing and still provide a desired display of the date. 
   Another object of the present invention is to provide a date display assembly that facilitates the reading of the date, even if the watch casing has been made smaller. 
   Another object of the present invention is to provide a date display assembly that can be manufactured easily and is very resilient to breakage or damage by a user. 
   Another object of the present invention is to facilitate the construction of such a date ring assembly, by using for example, a self-locking arrangement. 
   Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification. 
   The invention accordingly comprises the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims. 
   Therefore, in accordance with the present invention, and generally speaking, a date display assembly for a timepiece is provided. In a preferred embodiment, the timepiece comprises a casing, an house wheel that is rotationally engaged with a meshing wheel, and a display window for displaying a date, and the date display assembly comprises an outer date ring having a plurality of digits thereon and aligned in the casing such that each of the plurality of digits is appearable in the display window, wherein the outer date ring comprises at least two signaling notches spaced apart from one another; an inner date ring having a plurality of digits thereon and also aligned in the casing such that each of the plurality of digits is appearable in the display window; a date wheel, rotatably engageable with the meshing wheel, for rotating the outer date ring in a first direction; and an inner date ring driving wheel, rotatably engageable with the outer date ring, for rotating the inner date ring is a direction opposite the first direction. 
   One particular novel feature is that the inner date ring rotates upon each engagement of the at least two signaling notches with the inner date driving wheel. Another novel feature is that each rotation of the inner date driving wheel causes a rotation of the inner date ring. Still further, another novel feature is that the inner date ring driving wheel is provided with a plurality of first slots that engage both the notches on the outer date ring and a plurality of teeth associated with the inner date ring. 
   In another embodiment of the invention, the date display assembly comprises an outer date ring having a plurality of digits thereon and aligned in the casing such that each of the plurality of digits is appearable in the display window; an inner date ring having a plurality of digits thereon and also aligned in the casing such that each of the plurality of digits is appearable in the display window; wherein the outer date ring has an angled inner edge and the inner date ring has a complementary angled outer edge, wherein the angled inner edge of the outer date ring overlies and restricts the movement of the outer edge of the inner date ring towards the display window; and a lockdown ring, coupled to the casing, for locking down the outer date ring. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above set forth and other features of the invention are made more apparent in the ensuing Detailed Description of the Preferred Embodiments, when read in conjunction with the attached Drawings, wherein: 
       FIG. 1  is a perspective view of a timepiece constructed in accordance with the present invention, in which a section of the watch casing has been cut away to more particularly illustrate certain material elements thereof; 
       FIG. 2  is another perspective view of a timepiece constructed in accordance with the present invention, showing the incorporation of the two date ring assembly, along with other material elements being easily seen behind the date ring assembly; 
       FIG. 3  is a perspective view of a timepiece constructed in accordance with the present invention, showing yet further features of the present invention, in particular, parts of the date display assembly and the gear train that enables the present invention; 
       FIG. 4  is a perspective view of the underside of the date rings, again illustrating elements material to the present invention; 
       FIG. 5  is a close-up view of certain elements provided in the view of  FIG. 4 ; 
       FIG. 6  is a cross-sectional view of the timepiece illustrated in  FIG. 2 ; and 
       FIGS. 7–8  illustrate the mechanical workings of a prior art two-date ring construction. 
   

   Identically labeled elements appearing in different ones of the above-described figures refer to the same elements but may not be referenced in the description for all figures. 
   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Prior to making specific reference to the Figures, it should be understood that omitted herein are certain basic and very well known concepts as to the construction and function of an analog or chronograph watch. Accordingly, reference shall be made only to the important and material features of the present invention, it being assumed that one skilled in the art would be well able to construct the basic, and underlying analog watch without reference having to be made to the present application. For example, it is assumed that one skilled in the art is well able to design and construct a timepiece that has a conventional date ring, such as one having 31 numbers around the periphery thereof, and a gearing arrangement in which the turning of a series of gears, such as the center, hour and minute gears, permits and causes the date ring to rotate accordingly. 
   Therefore, while what will now be disclosed will completely enable one skilled in the art to construct a timepiece that incorporates an improved two date ring assembly in accordance with the present invention, the application is drafted with the underlying assumption that the basic workings of an analog gear movement and date ring assembly are known. 
   Accordingly, taking the following disclosure in connection with the Figures herein, it will be seen that the present invention is directed to an improved date display assembly for a timepiece, which is generally indicated at  1 . Timepiece  1  comprises a casing  10 , and a setting stem generally indicated at  15 , details of which will are well known in the art. 
   From the disclosure of the patents and applications incorporated by reference herein and as set forth below, it should be well understood how setting stem  15  will preferably include a toothed wheel (not shown) that can rotatably engage a setting wheel  20 . Setting wheel  20  in turn is in rotational engagement with a center wheel  23  (see  FIG. 3 ) which is mounted on a center stem  22 . A minute wheel  25  is mounted on or includes its own stem (not shown) and is in rotational meshing with center wheel  23 . A pinion  26  on minute wheel  25  is in rotational engagement with an hour wheel  30 , that is also mounted on center stem  22 , all of which is well known in the art. A meshing wheel  35 , mounted on (or including its own) stem (not shown), is rotatably engageable with hour wheel  30 . A display window  3  is provided through a dial  5 . 
   The objective of the present invention and as discussed below, is to maximize the size of the date digits that appear in date window  3 , while keeping the overall size of the watch within a desired (i.e. small) size. 
   Therefore, in accordance with the present invention, the date display assembly of the present invention comprises an outer date ring, generally indicated at  50 , that has a plurality of digits (see  FIG. 2 ) thereon (such as by printing them on or other known methods), all of which are aligned on the ring such that each of the digits will appear in display window  3  when outer date ring  50  rotates. 
   The date display assembly also comprises an inner date ring, generally indicated at  70 , that also has a plurality of digits thereon (see  FIG. 2 ), again such as by printing or the like. In a similar manner, ring  70  and the placement of the digits thereon are also aligned in the casing such that each of the digits can appear in display window  3 . 
   As illustrated, the present invention contemplates that there two series of digits ( 0 – 9 ) on outer date ring  50  and three series of digits ( 0 – 3 ) on inner date ring  70 . This 2:3 multiple is preferred because of the construction set forth below. 
   Driving outer date ring  50  is a date wheel  40  mounted on or including its own stem (not shown), which is rotatably engageable with meshing wheel  35 , and in particularly with a pinion  37  (see  FIG. 4 ) that is attached to or otherwise integral with meshing wheel  35 . Use of pinion  37  provides for the correct turning ratio between hour wheel  30  and outer date ring  50 , all of which should be understood by one skilled in the art. Details of the particular features and construction of date wheel  40  are discussed further below. 
   The date display assembly also comprises an inner date ring driving wheel  45 , mounted on stem  49 , rotatably engageable with outer date ring  50 , for driving inner date ring  70  in a direction opposite the direction in which the outer date ring  50  turns. 
   Generally speaking the novelty of the present invention resides in the idea that hour wheel  30  drives meshing wheel  35  which in turn drives date wheel  40  which in turn drives outer date ring  50  which in turn drives inner date ring driving wheel  45  which in turn drives inner date ring  70 . The coordinated gearing action and the particulars of each of the aforementioned elements to carry out this novel method of date display shall now be disclosed. 
   Particularly reference is now made to  FIGS. 4 and 5  for a disclosure on how date wheel  40  drives outer date ring  50 . Specifically, date wheel  40  includes a resilient arm  42  with a hand  43  at the end thereof, all of which may be integrally molded together from plastic. From the perspective of  FIG. 3 , date wheel  40  (and hence outer date ring  50 ) will rotate in the clockwise direction (of course due to hour wheel  30  rotating in the clockwise direction), while in the view of  FIG. 5 , date wheel  40  (and hence outer date ring  50 ) will rotate in the counterclockwise direction. Each time date wheel  40  rotates one revolution, it is desirable that hand  43  of resilient arm  42  engage and cause the incremental rotation of outer date ring  50 . 
   Specifically, outer date ring  50  includes a plurality of triangularly shaped teeth  51 . With each rotation of resilient arm  42 , hand  43  will rotate around and urge forward (in the counterclockwise direction when viewed in  FIG. 5 ) the tooth with which it will next contact, thus causing outer date ring  50  to rotate once every 24 hours of perceived or actual rotation of hour wheel  30 . From the foregoing, one can therefore see how outer date ring  50  rotates upon the rotation of hour wheel  30 , as the sizing of the wheels are coordinated so that each two revolutions (i.e. 24 hours) of wheel  30  causes a full revolution of wheel  40  which causes the appropriate angular rotation of outer date ring  50 . 
   Outer date ring  50  further includes two notches  52 ,  53  located slightly inwardly and, in the preferred embodiment, slightly below the plane that includes teeth  51 . In this way, notches  52 ,  53  lie in the plane with wheel  45 . These two notches  52 ,  53  are preferably molded on the underside surface of outer date ring  50  and are spaced directly opposite each other so as to cause the rotation of driving wheel  45  once every 10 th  actual or perceived day. These notches  52 ,  53  can be thought of as the “tens digit” driving information, because it is the interaction of wheel  45  (as discussed below) with these notches that cause the incrementing of the tens digit (i.e. from “09” to “10” and from “19” to “20” for example). These notches are the elements that are responsible for “signaling” the needed change of the tens digit of the date and the corresponding engagement of wheel  45  with one of the notches  52 ,  53 . Moreover, driving wheel  45  rotates only when it is time to rotate the inner date ring. 
   From the foregoing, it can be seen that there is no need to precisely align either the inner date ring or driving wheel  45 , since any initial or later resulting misalignment can be easily corrected by the appropriate advancement of the outer date ring, since the signaling elements, namely notches  52 ,  53  are always aligned in the same location on outer date ring  50 . With the “signaling” occurring by the notches on the outer date ring  50  and the advancement of the inner date ring occurring as a result of the rotation of wheel  45  as disclosed herein, the inventors hereof are assured a workable orientation no matter what the alignment is during assembly of the related components or resulting from a intermittent misalignment during later operation. That is, there is no possibility of permanent misalignment. 
   Moreover, notches  52 ,  53  are aligned and located on the undersurface of date ring  50  so that when the date goes from the 9 th  to the 10 th  of the month, from the 19 th  to the 20 th  of the month or the 29 th  to the 30 th  of the month, the respective notch  52  or  53  will engage driving wheel  45  and urge it in a counterclockwise direction (when viewing from  FIG. 5 ). It should thus be understood that notches  52  and  53  need to be positioned taking into consideration the location of the display window and the positions of the various wheels. In the preferred embodiment, although this is only by way of example and not limitation, the notches are located approximately under the “4&#39;s” of outer date ring  50 . It can also be seen that this arrangement advantageously does not require the precision alignment of the outer date ring with respect to the inner date ring because the notches are positioned on the underside of outer ring  50 . 
   Turning to the particulars of driving wheel  45 , it can be seen to have a plurality of slots, preferably four larger slots  46  alternating with four smaller slots  47 . As outer date ring  50  rotates counterclockwise in  FIG. 5 , notches  52  and  53  will each respectively contact an inner wall  48  of the larger slot  46  to thus urge driving wheel  45  in the counterclockwise direction about its stem  49 . The engagement of the respective notch  52  or  53  with each inner wall  48  is sufficient to cause driving wheel  45  to rotate sufficiently so that upon the next engagement of the other of notches  52  and  53 , it is with the next larger slot  46 , and not undesirably with one of the smaller slots  47 . From the foregoing, one skilled in the art could properly dimension driving wheel  45 , its respective slots  46  and  47  and the size of notches  52 ,  53  to ensure the proper amount of rotation of driving wheel  45  with each successive rotation caused by the notches  52 ,  53 . 
   Inner date ring  70  also includes a plurality of teeth on an interior sprocket that is preferably molded therewith, although the sprocket may be separate therefrom and coupled thereto, such as in a way similar to the cited prior art centerwheel. The teeth are preferably comprised of alternating larger teeth  71  and smaller teeth  72 . 
   Driving wheel  45  is oriented such that the smaller slots  47  receive and engage the smaller teeth  72 , while the larger slots  46  receive and engage the larger teeth  71 . Specifically, it was determined that the size of large slot  46  did not provide the desired amount of urging force to the sprocket of inner date ring  70 , thus requiring the assistance of the plurality of smaller slots  47 . More specifically, the slots of the wheel  45  and meshing teeth of the inner date ring are designed to avoid torque peaks while gearing, so as to not unduly burden the driving motor. As such, slots  46 ,  47  and corresponding teeth  71 ,  72  comprise a geometry to provide a very homogeneous transmission rate, another novel feature provided hereby. Hence, the sprocket of inner date ring  70  needs correspondingly sized teeth to accommodate and engage each sized slot  46 ,  47 . 
   It can thus be seen how the rotation of outer date ring  50  is directly caused by the rotation of driving wheel  40 , and in particular, the urging of arm  42  against each one of the teeth  51 . In turn, it can be seen how the rotation of driving wheel  45  is directly caused by the urging of notches  52 ,  53  against the inner walls  48  of larger slots  46 . Still further, it can thus be seen how the rotation of inner date ring  70  is caused by the urging of the inner walls of the respective larger slots  46  and smaller slots  47  against teeth  71 ,  72 . 
   From the foregoing, it can be seen that an improved date display assembly can be provided by the use of two date rings. Furthermore, the use of the date rings in accordance with the foregoing will require a user to adjust the displayed date at or about the end of each month, because it can be seen that the next displayed date after “31” for example will be “32,” and not “1.” Thus a user is required to be more aware of the settings on his/her own watch, another advantage afforded by the present invention. 
   In accordance with another feature of the present invention, outer date ring  50  comprises an angled inner edge  56 , while inner date ring  70  comprises a complementary angled outer edge  76 . In this way, only the outer date ring  50  needs to be locked down by conventional methods such as by ring  80 . Outer ring  70  is also biased in place by one or more spring arms  85 . In this way, the present invention allows for the outer date ring  50  to provide a self-locking inner date ring feature. The construction is as follows: inner date ring  70  is restrained from vertical movement at its outermost edge by the complementary beveled edge  56 , thereby ensuring that the inner date ring  70  can remain properly positioned without the use of any clamps, springs or other lockdown components on the outer edge of ring  70 . On the other hand, outer date ring  50  is held down by ring  80 . Hence a two-ring date display assembly can be configured with a minimum number of parts, thus achieving another advantage of ease and simplicity in assembly construction. Moreover, it can be seen that the wheel  45  is horizontally aligned with the inner and outer date rings, as set forth above. Still further, the dial, which one would readily appreciate is positioned on top of the inner and outer date rings, also provides the function of keeping the rings vertically restrained. 
   While the invention has been particularly shown and described with respect to preferred embodiments thereof, it will be understood by those skilled in the art that changes in form and details may be made therein without departing from the scope and spirit of the invention. It should also be understood that reference to rotatable “engagement” or “meshing” or similar terms are all used interchangeably and not intended to indicate different meanings. 
   For example, the present invention has been disclosed above with particular reference to timepieces. However, one skilled in the art shall now appreciate that the present invention is equally applicable, and as claimed herein, to devices other than timepieces, such as, but not limited to clocks. 
   By way of background, one may wish to review U.S. Pat. No. 5,305,291, 5,742,565, 5,446,703, or 5,210,772, or the subject matter of a copending application entitled Hour Hand Setting Assembly For An Analog Timepiece, Attorney Docket No. A0713A, filed on Dec. 30, 2002 to Siegfried Grau, the subject matter of all these patents and application being incorporated by references as if fully set forth herein.