[1]United States Patent Office 3,490,226 3,490,226 CLOCK FACE ASSEMBLY HAVING ILLLTMINATED INDICATING ELEMENTS Wilmer C. Anderson and Louis Altman, Stamford, Conn., assignors to General Time Corporation, Stamford, Conn., a corporation of Delaware Filed Nov. 20, 1967, Ser. No. 684,117 U.S. Cl. 58-50 Int. Cl. G04b 19130 4 Claims ABSTRACT OF THE DISCLOSURE A clock face assembly in which the clock hands or other time indicating elements are illuminated by a single stationary light source located at the center of the assembly. Light transmitting means are mounted for rotational movement at different controlled angular velocities around the light source while continuously transmitting light from the source either into light transmitting illuminatable clock hands, or onto light reflecting surfaces. The light transmitting means which rotate around the stationary light source are shown as being driven either from the periphery of the assembly or by a center drive. In one embodiment, the light transmitting illuminatable clock hands are formed as integral parts of light transniitting sleeves which rotate around the stationary light source. In another embodiment, two sleeves havin.- light transmitting openings therein rotate around the stationary light source and project radial light beams onto continually changing positions on a pair of light reflecting surfaces which surround the rotating sleeves, the two light reflecting surfaces being located at two different radial positions. This invention relates generally to timepiece display arrangements and, more particularly, to an improved clock face assembly having illuminated hands. It is a primary object of the present invention to provide an improved clock face assembly in which the clock hands are continuously illuminated by a single stationary light source. A related object is to provide such an improved clock face assembly which utilizes a single stationary light source to illuminate the clock hands uniformly at all positions and without the production of shadows, even though the cl6ck hands are driven at different controlled angular velocities. A further object of the invention is to provide an improved clock face assembly of the foregoing type which provides a sharp contrast between the illuminated clock hands and the background of the display area. In this connection, it is an object of the invention to provide such a clock face assembly which gives a clear and distinct indication of the time even at substantial distances. Still another object of the invention is to provide a clock face assembly with illuminated hands which is extremely versatile with regard to the variety of illuminative and decorative effects that can be obtained by only slight modifications of the assembly. It is another object of the invention to provide an illuminatedhand clock face assembly of the type described above which requires only a few parts that can be economically manufactured, assembled, and maintained. A related object is to provide such a clock face assembly which is susceptible to high volume production. Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which: FIGURE 1 is a front view of a clock face assembly embodying the present invention; FIG. 2 is a vertical section taken along line 2-2 of FIG. 1; Patented Jan. 20, 1970 2 FIG. 3 is a section taken along line 3-3 in FIG. 1; FIG. 4 is a section taken alorig line 4-4 in FIG. 1; FIG. 5 is a front view of a modified form of a clock face assembly embodying the present invention; F IG. 6 is a vertical section taken along line 6-6 in F IG. 5; F IG. 7 is a section taken along line 7-7 in FIG. 5; a nd . ' FIG. 8 is a partial vertical section of a further modified lo form of a clock face assembly embodying the present invention. While the invention will be described in connection with certain preferred embodiments, it will be understood that it is not intended to limit the invention to these par15 ticular embodiments. On the contrary, it is intended to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention. Referring now to the drawings and turning first to 20 FIGURES 1 through 4, there is shown a clock face assembly which includes an annular dial plate 10 having the usual hour numbers displayed thereon. The dial plate 10 rests on a circular flange 11 extending around the periphery of a circular opening formed by a casing 12 25 which also houses a timing mechanism (not shown) for driving hour and minute hands at the required speeds so that the time is displayed in the usual manner by the position of the hands relative to the numbers on the dial plate. In order to close the front of the opening to pro30 tect the interior of the clock from dust and the like, a transparent lens 13 is fitted against the front of the dial plate 10 and held thereagainst by means of a snap ring 14 which also serves as trim around the periphery of the lens and dial plate. The snap ring 14 is typically provided 35 with a plurality of lugs spaced around its periphery and adapted to fit into corresponding notches formed in the casing 13. In accordance with the present invention, the clock face 40 assembly includes a light source positioned at the center of the dial plate, a pair of hour and minute indicating elements made ofa light transmitting material and mounted for angular movement around the light source so as to transmit light from the source along continually chang45 ing radial paths to indicate the time, and drive means for rotating the indicating elements at different controlled angular velocities while continuously maintaining a light transmission path between the light source and the indicating elements. Thus, in the particular embodiment of the 50 invention illustrated in FIGURES I through 4, a stationary light bulb 20 is mounted in the center of the clock face in a fixed socket 21 connected to an appropriate power source through the rear of the clock. The light source 20 is positioned slightly rearwardly of the 55 dial plate 10 for purposes which will become apparent from the ensuing description. For the purpose of indicating the time on the dial plate 10, a pair of illuminatable clock hands 22 and 23 made of a light transmitting material extend radially outward60 ly from a pair of integral sleeves 24 and 25, respectively, disposed concentrically around the light source 20. The clock hands 22, 23 and the integral sleeves 24, 25 are suitably made of clear polystyrene, an acrylic resin such as "Lucite" or "Plexiglas," or any other suitable illumi65 natable light transmitting material. As the clock hands 22, 23 rotate around the light source 20, light is continuously transmitted through the sleeves 24, 25 and on through the radially extending hands 22, 23 so as to illuminate the hands uniformly along the entire length thereof. To make 70 the visible portion of the hour hand 22 shorter than the minute hand 23, the radially outer portion of the hour hand 22 is coated with an opaque material such as ail
[2]3)4901226 3 opaque black paint, as indicated at 26, so that only the radially inner portion of the hour hand is illuminated, while the minute hand 23 is illuminated all the way out to the edge of the dial plate 10. If desired, the opaque coating can be replaced by an appropriate light shield made of opaque material. It will be understood that the relative lengths of the visible portions of the two hands 22, 23 may be varied to any desired length by simply coating more or less of the two light transmitting rods. Also, an endless variety of different designs and illuminative effects can be achieved by simply varying the configuration of the light transmitting materials. If desired, different color effects may be obtained by simply adding a suitable pigment to the indicating elements when they are molded. In order to make the illuminated clock hands 22, 23 distinctly visible, a dark background plate 30 is fitted against a complementally formed shoulder 31 on the inside surface of the casing 12 so as to provide a dark background against which the clock hands 22, 23 are viewed. This provides a sharp contrast between theilluminated hands and the background area of the display field. A forwardly projecting ffange 32 on the inner periphery of the background plate 30 fits into the rear sleeve 25 to provide a supplemental guiding support for the time indicating elements. The background sleeve 30 is held firmly in place by means of a conventional snap ring 33 fitted within a cooperating groove formed in the casing 12 just behind the plate 30, so that it can be quickly assembled for high volume production. For the purpose of restricting the light transmitted from the source 20 through the sleeves 24, 25 to the @particular portions of the sleeves that merge with the clock hands 22, 23, the outside surfaces of the two sleeves 24, 25 are preferably coated with an opaque material similar to that applied to the radially outer portion of the hour hand 22. This opaque coating prevents the diffusion of light from around the entire circumference of the two sleeves 24, 25, so as to eliminate or minimize illumination of the background plate 30 and maintain a maximum contrast between the illuminated hands and the dark background. In addition, an opaque cap 34 is snapped over the front end of the sleeve 24 so as to conceal both the light source 20 and the sleeves 24, 25 from the viewer in front of the clock. This cap may be removable to facilitate replacement of the bulb 20. In addition, it should be noted that the opposed ends of the two sleeves 24, 25 are preferably ,provided with overlapping flanges as indicated at 35 so as to provide an interlocking arrangement which helps maintain the two sleeves in alignment with each other an,d to strengthen the unit against mechanical shocks or vibration. In keeping with the present invention, the two illuminated clock hands 22, 23 are driven at controlled angular velocities by a drive arrangement which does not interfere with the light transmission path between the light source 20 and the inner ends of the two hands 22, 23. Thus, in the illustrative embodiment of FIGURES I through 4, a pair of ring gears 40, 41 are provided at the outer ends of the two hands 22, 23 as integral parts thereof. The two ring gears 40, 41 mesh with a pair ofcooperating pinions 42, 43 connected to the timing mechanism (not shown) so that the pinion 42 drives the hour hand 22 at a controlled speed of one revolution per twelve hours, while the pinion 43 drives the minute hand 23 at a controlled speed of one revolution per hour. The pinions 42, 43 are preferably mounted in the clearance provided between one of the corners of the square casing 12 and the circular dial. Since the drive for the clock hands 22, 23 is thus located beyond the outer ends of the hands, the light transmission path between the source 20 and the inner ends of the hands is never obstructed at any angular position of the hands. The same integral rings which form the two gears 40, 41 project forwardly from the gear teeth so as to form a pair of continuous circumferential guide beads 44, 45 4 which cooperate with three identical pairs of complementally formed guide wheels 46, 47 mounted within the other three corners of the casing 12. To reduce wear on the guide beads 44, 45 and also facilitate assembling of the unit, each of the guide wheels 46, 47 is journaled on the end of a supporting arm 48 which is pivoted at its outer end on the casing 12 and biased inwardiy toward the guide beads 44, 45 by means of a spring 49. Consequently, the entire movable portion of the time indicat10 ing arrangement is supported at all four comers, with three of the support points being provided by the biased guide wheels 46, 47 and the fourth support point being provided by the drive pinions 42, 43. The resilient supports at three of the f our corners enable the unit to ab15 sorb mechanical shocks and vibration without excessive wear or breakage. In accordance with a modified embodiment of the invention, the time indicating elements which move around the light source direct the light radially outwardly to a 20 pair of stationary reflecting members which reflect the light forwardly toward the viewer in front of the clock lens. Thus, in the particular embodiment illustrated in FIGURES 5, 6, and 7, the drive train of the clock is connected to a pair of concentric sleeves 50 and 51 which 25 rotate around a stationary light source 52 at speedscorresponding to those of conventional hour and minute hands. An integral flange 50a on the outside of the inner sleeve 50 engages the inside surface of the outer sleeve 51 to hold the forward portions of the concentric sleeves 30 slightly spaced apart. The two sleeves 50 and 51 are provided with light transmitting openings 53 and 54, respectively, which transmit light from the source 52 radially outwardly to a pair of beveled reflecting surfaces 55 and 56. The surfaces 55, 56 in turn reflect the light beams 35 from the openings 53, 54 forixiardly through the clock lens, as indicated by the arrows in FIG. 6. The two reflective surfaces 55, 56 extend continuously around the entire circumference of the sleeves 51, 52 so that as the sleeves are rotated the light beams transmitted 40 through the sleeve openings 53, 54 move angularly over the reflective surfaces, with a constant shape defined by the configuration of the two openings 53, 54. In the particular embodiment illustrated, the light beam indicating the minutes, i.e., the light transmitted through the inner 45 sleeve 53, is diamond-shaped, while the light beam indicating the hours is square, to enable the viewer to readily distinguish between the hour and minute indications. in addition, the hour indicator is spaced radially inwardly from the diamond-shaped hour indicator so that the reIjo flected light areas seen by the viewer appear as shown in FIG. 5, with the hourindicating area closer to the center of the face than the minute-indicating area. In order to provide a dark background for maximum contrast with the illuminated clock hands, a background plate 57 similar 55 to the plate 30 described above is mounted behind the rear reflector element 56. The two reflector elements are held in place against the clock casing 58 by means of the same snap ring 59 that holds the background plate 57 in place. (o In accordance with one particular aspect of this invention, the light source 52 in the embodiment of FIGURES 5 through 7 is mounted in a socket 60 supported within a concealing cap 61 directly in front of the two rotating sleeves 50, 51. The outside diameter of the cap 61 is slightly greater than the outside diameter of the outer 6,5 sleeve 51 so that the sleeve stack is completely concealed from the viewer in front of the clock lens. To support the concealing cap 61 and the socket 60 mounted therein, a pair of thin supporting legs 62 mount the cap 61 on the forward reflective member 55. One of the supporting legs 70 62 is hollow so as to serve as a conduit for carrying the electrical wires from the socket 60 to a contact element 63 extending back through the two reflective members (see FIGURE 7) for connection to a power line 64. It will be appreciated that the two supporting legs 62 may 7,5 be made extremely thin and may even be made of trans-
[3]5 parent material so that there is practically no visibleobstruction of the reflected-light time indicators as they pass the legs. In order to transmit the light through the opening 54 in the outside sleeve 51, that portion of the inner sleeve 50 underlying the opening 54 must be made of a transparent material. The balance of the outside surfaces of both sleeves 50 and 51 are preferably coated with an opaque material in order to prevent diffusion of light onto the background panel 57 and the portions of the reflective surf aees 55, 56 which are not directly illuminated by the light beams from the two openings 53, 54. In addition, the interior surfaces of the two sleeves 50, 51 are preferably coated with a highly reflective material (except for the transparent portion of sleeve 50 underlying opening 54) to increase the intensity of the light beams transmitted through two openings. In a further emb.(>diment of the invention, illustrated in FIGURE 8, the time indicator arrangement is similar to that of FIGS. 5-7 except that the light is transmitted directly from a pair of concentric sleeves 70, 71 into a pair,of illuminatable clock hands 72, 73 made of a light transmitting material similar to that employed for the hands 22, 23 in the embodiment of FIGURES I through 4. In order to permit the transmission of -light through the inner sleeve 70 to the minute hand 73, that portion of sleeve 70 underlying the minute hand 73 must be transparent, although it is preferred to coat the balance of the exterior sleeve surfaces with an opaque material to minimize light diffusion as described previously. Similarly, the interior sui-faces of the sleeves are preferably made reflective (except for the portion of the inside sleeve 7 1 0 underlying minute hand 73) to intensify the light transmitted through the hands. As can be seen from the foregoing detailed description, this invention provides an improved cl<)ck face assembly in which the clock hands are continuously illuminated by a single stationary light source located at the center of the assembly. The clock hands are uniformly illuminated at all positions without the production of shadows, and with a sharp contrast between the illuminated hands and the background of the display area so as to give a clear and distinct indication of the time even at substdntial distances from the clock. The assembly is extremely versatile in that a variety of illuminative and decorative effects can be obtained by only slight modifications. Moreover, the assembly can be economically manufactu@ed from only a relatively small number of parts, and is readily susceptible of high volume production. We
