Abstract:
A clock is disclosed having a seemingly gravity-defying time-indicating element adjacent a substantially vertically disposed dial. A magnetic guide element is positioned behind the dial for movement around the dial as a function of time. A magnetically responsive time-indicating element such as a metallic-appearing sphere is positioned for viewer visibility in front of the dial, and is less dense than it appears. The time-indicating element is magnetically coupled to the time-indicating element for movement therewith around the front of the dial in apparent defiance of gravity to indicate the time without becoming decoupled from the guide element.

Description:
[0001]    This invention relates in general to clocks and, more particularly, to a clock having at least one magnetically-responsive time-indicating element disposed in front of a dial that is moved by a guide element disposed behind the dial via magnetic interaction.  
         BACKGROUND OF THE INVENTION  
         [0002]    Chronometric instruments are frequently designed to include visually engaging characteristics. Since all such instruments perform the basic utilitarian function of indicating time, purchasers typically select a particular clock or watch based upon other factors such as aesthetics, eye-catching mechanisms, and the like which render the instrument a conversation piece.  
         DESCRIPTION OF THE PRIOR ART  
         [0003]    In the past, disclosed clocks and watches have utilized magnetically responsive elements in an attempt to create eye-catching illusions. U.S. Pat. No. 5,805,531 for example discloses a watch having a guide element, a time indicator element and a dial interposed between the two. The guide element moves clockwise behind the dial as a function of time. The indicator element is magnetically coupled to the guide element to accordingly move clockwise around the front of the dial. The patent discloses that the indicator element can become decoupled from the guide element, however, so a cage structure is provided between the dial and the watch glass to capture the time indicator and prevent it from being lost when decoupled. The decoupled time indicator is permitted to move freely about the cage. The watch can consequently be pivoted back and forth until the indicator element is recaptured by the magnetic field of the guide element, enabling the time to be read. This watch lacks a gravity-defying structure or appearance and, in fact, provides for the visually-apparent capture of the time-indicating element in normal use.  
           [0004]    Another use of a magnetic field is disclosed in U.S. Pat. No. 5,638,340 wherein a ferromagnetic ball is described as being magnetically levitated for reciprocal movement under feedback control to appear as a levitated pendulum.  
           [0005]    Still another use of a magnetic field to create a visual illusion is disclosed in U.S. Pat. No. 4,723,232 wherein a clock has a pendulum suspended from a point above the clock dial. The pendulum comprises a magnetically responsive bob that is intermittently coupled to an electrically-pulsed electromagnet under the dial that momentarily holds the bob at time indicating positions vis-à-vis the dial. Unlike the time indicator element in the &#39;531 Patent, above, this ball is tethered by a string, rather than free and also lacks a gravity-defying appearance  
           [0006]    It is an object of this invention to provide a clock that displays time in a novel and innovative manner through the use of a seemingly gravity-defying time-indicating element.  
           [0007]    It is a further object of this invention to provide a clock, which reliably indicates the time at a glance.  
         SUMMARY OF THE INVENTION  
         [0008]    The invention herein is a clock with a seemingly gravity-defying time-indicating element comprising a dial, a guide element formed at least in part from magnetically responsive material and positioned behind the dial for movement around the dial as a function of time, a time-indicating element positioned for viewer visibility in front of the dial, the time-indicating element being less dense than the density of magnetically-responsive material, and a magnetically-responsive coupling element mechanically coupled to the time-indicating element for movement therewith and magnetically coupled to the guide element through the dial for responsive movement of the time-indicating element.  
           [0009]    These and other features of the invention will become apparent from the following description of the preferred embodiment, of which the drawing is a part. 
       
    
    
     DESCRIPTION OF THE DRAWING  
       [0010]    In the drawing,  
         [0011]    [0011]FIG. 1 is a front elevation view of a preferred clock constructed in accordance with the invention; and.  
         [0012]    [0012]FIG. 2 is a cross-sectional view of the clock depicted in FIG. 1, taken along line  2 - 2  in FIG. 1;  
         [0013]    [0013]FIGS. 3 a - d  are respectively enlarged sectional views of the time-indicating element of FIG. 2 showing alternative structures thereof;  
         [0014]    [0014]FIG. 4 is an enlarged view of a portion of FIG. 2 showing the area of the clock adjacent the time-indicating element; and  
         [0015]    [0015]FIG. 5 is a front sectional view in schematic along the line  5 - 5  in FIG. 2 showing a preferred arm mounted for rotational movement within the clock housing. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0016]    [0016]FIG. 1 is a front elevation view of a preferred clock  10  constructed in accordance with the invention. The clock  10  comprises a generally vertically oriented diall 2  having conventional time-indicative indicia circumscribing the dial in the conventional manner. It should be recognized, of course, that other indicia may be used instead, and that no indicia may even be necessary, owing to the viewers&#39; inherent knowledge of the numbers that should be at the respective positions on the face of the dial. Indicia may be placed on the dial by silk screening, engraving, embossing or any other imprinting process. Those skilled in the art will recognize that the dial may be integral with the clock housing  42 , as by forming indicia directly onto the housing, or may be a separate structure affixed to the clock in any manner.  
         [0017]    A time-indicative element  14  is positioned on the face of the dial  12  at the 12 o&#39;clock position. As will be explained below, the element  14  moves clockwise around the dial as a function of time with no visible means of support. The illustrated clock has a minimalist design in that the element  14  functions as an hour hand, and the time between whole hours is estimated by its position between adjacent indicia. Those skilled in the art will recognize that the clock herein need not be limited to a single indicating element, however.  
         [0018]    Turning to FIG. 2, the clock dial  12  is mounted for support on the front exterior surface of the clock housing  42 . The time-indicating element  14  is held against the dial  12  by the magnetic attraction to a guide element  16  mounted within the clock housing behind the dial and on one end of a clock arm  18 . The arm  18  has a spindle-accommodating aperture  20  through its mid-region which accommodates the spindle of a clock motor (not shown) for rotation about axis  22  as a function oftime. The guide element is preferably formed with a pocket  17  in which a small magnet  19  is retained. Those skilled in the art will recognize that numerous other techniques for rendering the guide element  16 , or the end of the arm  18 , magnetic could be employed without departing from the scope of the invention.  
         [0019]    AS best shown in FIG. 4, the pocket  17  is preferably sized to loosely capture the magnet  19  so that the magnet can still move towards the dial in response to the magnetic coupling with the time-indicating element. Allowing this movement substantially prevents the time-indicating element  14  from tending to pivot the arm  18  about the spindle. That pivoting movement could bend the arm  18 , unduly wear bearings within the clock motor which support the spindle, and otherwise impose an undesirable force on the clock movement. The magnet  19  can be any of a number of shapes including but not limited to cylindrical, annular cubic, etc.  
         [0020]    Returning to FIG. 2, the guide element  16  is positioned behind the clock dial  12  for clockwise movement around the dial as a function of time. The time-indicating elementl 4  is magnetically coupled through the dial  12  to the guide element  16  for movement around the dial therewith. The time-indicative element  14  is preferably ball-shaped or cylindrically shaped to minimize the area of surface contact between the element  14  and dial  12 , and thereby minimize friction as the element moves upon the dial surface.  
         [0021]    It is highly desirable to prevent the time-indicating element  14  from falling off the generally vertical dial of the clock because the clock will be non-functional without it. Unlike the watch disclosed in U.S. Pat. No. 5,805,531 which has a generally horizontal dial that is easily pivoted by wrist motion and the like to recapture the time-indicating element if it becomes decoupled, the clock herein has a generally vertical dial, is typically much larger than a watch and is typically mounted in a stationary manner. It is desirable to accomplish this without the use of heavy powerful magnets, since the use of such magnets would increase the torques required to move the time-indicating element as well as the amount of friction between the time-indicating element and the clock&#39;s dial. Accordingly, the element  14  is preferably formed as a substantially hollow ball or cylinder of lightweight plastic. By providing a density much lighter than that of an element formed wholly of magnetically responsive material, less force is required to reliable retain magnetic coupling between the generally vertically oriented clock dial and the time-indicating element  14 . Moreover, the element  14  may be painted to appear metallic, enhancing the visual perception of a relatively heavy metallic element that is defying gravity.  
         [0022]    To make the element  14  magnetically responsive, a small lightweight magnet or magnetically responsive element  24  is positioned within the element  14  to couple it to the guide element  16  without adding an amount of weight that would tend to decouple it from the clock. It should be recognized, of course, that one or both of the element  24  and guide element  16  could comprise a magnet, and that one of the two could alternatively be formed from a magnetically-responsive metal without departing from the invention. In the preferred embodiment, the guide element  16  and the element  24  both comprise rare earth magnets, providing strong magnetic attraction with less required weight.  
         [0023]    [0023]FIGS. 3 a - d  are enlarged sectional views of the time-indicating element  14  showing some of the alternative structures that may be utilized. FIG. 3 a  illustrates the embodiment shown in FIG. 2. The time-indicating element  14  of FIG. 3 a  comprises a pair of mating hemispheres  32 ,  34  that sealingly abut along respective generally circular faces at  36  to form a generally hollow sphere. Each of the hemispheres  32 ,  34  has an open-ended, generally cylindrical wall  37 ,  38  extending inwardly from the inside wall of the hemisphere towards and beyond the plane of the hemisphere&#39;s circular face. The diameters of the cylindrical spacesthus enclosed are such that the inwardly extending cylindrical wall of one hemisphere extends within the cylindrical wall of the other hemisphere when the two hemispheres are brought into abutting position as illustrated. The magnet or magnetically responsive element  24 , as the case may be, is cylindrically shaped, and placed within the narrower of the two cylindrical spaces prior to assembling and sealing the hemispheres, capturing it within the close-ended tubular space thusly formed. As illustrated in FIG. 3 a,  the magnetic element  24  is freely movable in only one direction (i.e., horizontally), keeping the magnet&#39;s poles oriented for best magnetic coupling when the time-indicating element is positioned onto the dial  12 . Moreover, the orientation of the tubular space defined by this configuration ensures that the equatorial seam formed at the interface between the abutting hemispheres will be generally parallel to the face of the dial and, therefore, less visible to an observer so that the visual effect of a seemingly solid element is enhanced.  
         [0024]    Alternatively, as shown in FIG. 3 b,  a spherically shaped element  24   a  of magnetically responsive material may be placed within a hollow sphere or cylinder-shaped time-indicating element  14   a,  and permitted to freely move into a magnetically coupled position when placed against the clock dial. This permits the time-indicating element to be mounted to the dial in any orientation. As illustrated in FIG. 3 c,  a spherically shaped element  24   b  can be placed within a pair of hemisphere-shaped bodies having an internal structure like that shown in FIG. 3 a.  As shown in FIG. 3 d,  a lightweight foam element  14   c  of open-celled or closed-cell material, for example, can also be utilized with a spherical, cylindrical or other conveniently-shaped magnetic element  24   c.  Lastly, a lightweight material can be mixed with iron filings to form the time-indicating element as well.  
         [0025]    Naturally, semi-cylindrical bodies could be used to form a cylindrical time-indicating element, etc. The invention is not limited to the particular shape of the time-indicating element in that regard. In addition, the magnetic element  24 ,  24   a  can alternatively be affixed in place by glue or other means, although the permitted free movement within the enclosed time-indicating element  14  permits the element  14  to be placed in a coupling relationship with the guide element  16  with less manual manipulation since the magnetic element  24  can move within the element  14  to correctly align with the magnetic field.  
         [0026]    In accordance with the invention, the preferred clock has a number of features incorporated to enhance the movement of the time-indicating element  14  and guide element  16  in a reliable manner. As shown most clearly in FIGS. 4 and 5, the preferred dial is mounted on the front exterior surface of the clock housing  42 . The rear face of the dial is provided with a circumferential rib  44  in the region contacted by the magnet  19  as it travels clockwise as a function oftime. Those skilled in the art will recognize that this rib is formed in the interior front face of the clock housing when the dial is integrated part of the housing such as by molding, engraving, embossing the indicia onto the exterior front face of the housing. The rib  44  substantially reduces the contact surface area of the magnet  19  and rear dial surface, reducing the generated friction for smooth movement and reduced wear. Alternatively, the rib can be formed on the frontward-facing surface of the guide element  16 , and other friction reducing means known in the art can be used in addition to, or instead of, the rib.  
         [0027]    To further reduce friction and wear, the arm  18  on which the guide element  16  sits is counter-weighted at the end opposite the guide element to balance the moment arms about the motor spindle. As shown in FIG. 5, the arm  18  has a relatively wider distal segment  52  at the end opposite the guide means  16 . When the clock motor rotates the arm  18 , it is working against the weight of the magnet  19  and the friction between the magnet  19  and rear dial face (with or without a friction-reducing structure such as the rib  44 ). These forces act through moment arms in accordance with known physical laws. The counterweight of the arm&#39;s distal end serves to substantially offset these forces through an opposing moment arm.  
         [0028]    While the foregoing description includes detail, which will enable those skilled in the art to practice the invention, it should be recognized that the description is illustrative in nature and that many modifications and variations will be apparent to those skilled in the art having the benefit of these teachings. It is accordingly intended that the invention herein be defined solely by the claims appended hereto and that the claims be interpreted as broadly as permitted in light of the prior art.