Abstract:
A timepiece movement ( 10 ) is disclosed as including an hour-wheel ( 12 ) with an hour-shaft ( 12   a ) to which an hour-hand is securable, a minute-wheel ( 14 ) with a minute-shaft ( 14   a ) to which a minute-hand is securable, a seconds-wheel ( 16 ) with a seconds-shaft ( 16   a ) to which a seconds-hand is securable, a light emitter ( 18 ) for emitting light, and a light receiver ( 20 ) for receiving the light emitted by the light emitter ( 18 ), in which the hour-shaft ( 12   a ) includes a first aperture ( 12   b ), the minute-shaft ( 14   a ) includes a second aperture ( 14   b ) and the seconds-wheel ( 16 ) includes a third aperture ( 16   b ), and the apertures ( 12   b,    14   b,    16   b ) allow the light emitted by the light emitter ( 18 ) to pass through, and to be received by the light receiver ( 20 ) only when the hour-wheel ( 12 ), the minute-wheel ( 14 ) and the seconds-wheel ( 16 ) are in a respective predetermined reference position.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    This invention relates to a timepiece movement and, more particularly, a timepiece movement which can detect when an hour wheel and a minute wheel are in predetermined reference positions, e.g. at the 12 o&#39;clock position (i.e. 12 hours and zero minute), detect any difference between the time at which this 12 o&#39;clock time is displayed and the actual time, e.g. as received from an external source by a receiver of the timepiece, and correct any error in the time displayed by the timepiece.  
           [0002]    There are in existence a number of prior arrangements of timepiece movements. U.S. Pat. No. 4,645,357 issued to Allgaier et al. discloses a timepiece which receives an externally transmitted radio signal corresponding to an accurate time of day. Disposed within the timepiece is a detecting mechanism for detecting the time of day being displayed by the timepiece. The signals are compared to determined the accuracy of the timepiece. The detection mechanism comprises an optoelectrical system which includes an emitter for directing a beam of radiation towards a sensor. The wheel of the gearworks intersect the beam ahead of the sensor to normally block the beam from the sensor. The wheels include orifices which, when aligned with the beam, permit the beam to reach the sensor, thereby providing an indication of the position of the wheels, and thus of the time being displayed.  
           [0003]    U.S. Pat. No. 5,231,612, also issued to Allgaier et al., discloses a radio-controlled timepiece with a mechanism for the detection and correction of a hands setting. A hands setting mechanism includes an hour wheel, a minute wheel, and a second wheel, each possessing an aperture therethrough. The hour wheel has a front mirror located proximate a beam sender for reflecting a beam to a receiver. The front mirror has an interruption defined by the aperture of the hour wheel in order to pass the beam through that aperture to a rear mirror disposed remote from the beam sender, such that a beam reflects from the rear mirror only after passing through aligned apertures in the wheels. The hour wheel is movable independently of the minute wheel and seconds wheel, and the minute wheel and seconds hand are rotatably interconnected.  
           [0004]    U.S. Pat. No. 5,566,140 issued to Kohata et al. discloses a clock movement including a circuit board, first and second motors, a minute wheel connected to the first motor by a first gear train and an hour wheel connected to the second motor by a second gear train. A first detection device detects when the minute hand is in a predetermined reference position and a second detection device detects when the hour hand is in a predetermined reference position. The first detection device includes a minute detection sensor mounted on the circuit board and having a first light-emitting device and a first light-receiving device. The second detection device includes an hour detection sensor mounted on the circuit board and having a second light-emitting device and a second light-receiving device.  
           [0005]    U.S. Pat. No. 5,930,205 issued to Baba et al. discloses a timepiece movement comprising a light-emitting device for emitting light and a light-receiving device for receiving the light emitted by the light-emitting device. An hour wheel has a number of apertures through which light from the light-emitting device may pass. A minute hand has an aperture through which light from the light-emitting device may pass, the aperture being positioned to become aligned with respective ones of the apertures of the hour wheel during rotation of the minute and hour wheels. Minute and hour wheel gear trains respectively rotate the minute wheel and the hour wheel as a function of minute and hour time.  
           [0006]    The contents of these prior art documents are incorporated by reference herein.  
           [0007]    In these conventional arrangements, the light passes through apertures provided on the hour wheels and minute wheels. As there is a relatively large gap between these wheels, there will be loss due to light refraction. Some of these prior arrangements, e.g. the timepiece movements disclosed in U.S. Pat. Nos. 4,645,357 and 5,566,140, include two sets of light-emitting members and light-receiving members, which adds to the cost of production.  
           [0008]    It is thus an object of the present invention to provide a timepiece movement in which the aforesaid shortcomings are mitigated, or at least to provide a useful alternative to the trade and public.  
         SUMMARY OF THE INVENTION  
         [0009]    According to a first aspect of the present invention, there is provided a timepiece movement including at least a first wheel with a shaft to which an hour-hand or a minute-hand is securable; a signal emitter adapted to emit signals; and a signal receiver adapted to receive said signals emitted by said signal emitter; wherein said shaft includes an aperture allowing said signals emitted by said signal emitter to pass through when said first wheel is in a predetermined reference position.  
           [0010]    According to a second aspect of the present invention, there is provided a timepiece including a timepiece movement, said timepiece movement including at least a first wheel with a shaft to which an hour-hand or a minute-hand is securable; a signal emitter adapted to emit signals; and a signal receiver adapted to receive said signals emitted by said signal emitter; wherein said shaft includes an aperture allowing said signals emitted by said signal emitter to pass through when said first wheel is in a predetermined reference position. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    A preferred embodiment of the present invention will now be described, by way of an example only, with reference to the accompanying drawings, in which:  
         [0012]    [0012]FIG. 1 is a partial sectional view of a timepiece movement according to the present invention;  
         [0013]    [0013]FIG. 2 is a side view of an hour-wheel of the timepiece movement shown in FIG. 1;  
         [0014]    [0014]FIG. 3 is a side view of a minute-wheel of the timepiece movement shown in FIG. 1;  
         [0015]    [0015]FIG. 4 is a top view of a seconds-wheel of the timepiece movement shown in FIG. 1; and  
         [0016]    [0016]FIG. 5 is a block diagram of a microcontroller unit suitable for use in the timepiece movement shown in FIG. 1. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0017]    A partial sectional view of a timepiece movement, e.g. a movement for a watch, according to the present invention is shown in FIG. 1, and generally designated as  10 .  
         [0018]    The timepiece movement  10  includes an hour-wheel  12  fixedly secured with a hollow hour-shaft  12   a , to which an hour-hand (not shown) may be fixedly secured. The hour-wheel  12  is rotatable by a motor (not shown) as a function of hour time. As can be seen more clearly in FIG. 2, near the bottom of the hour-shaft  12   a  is provided with a small opening  12   b , the function of which will be discussed below.  
         [0019]    The timepiece movement  10  also includes a minute-wheel  14  fixedly secured with a hollow minute-shaft  14   a , to which a minute-hand (not shown) may be fixedly secured. The minute-wheel  14  is rotatable by a motor (not shown) as a function of minute time. The minute-shaft  14   a  is sized and configured to be receivable within the hollow hour-shaft  12   a  for co-axial rotational movement about a longitudinal axis L-L, which is parallel to the longitudinal axis of the hour-shaft  12   a  and that of the minute-shaft  14   a . As in the case of the hour-shaft  12   a , and as shown in FIG. 3, near the bottom of the minute-shaft  14   a  is provided with a small opening  14   b . The positions of the small openings  12   b  and  14   b  are such that when the hour-wheel  12  and the minute-wheel  14  are assembled for co-axial rotational movement about the axis L-L, the openings  12   b  and  14   b  may be rotated into alignment with each other to collectively form a continuous and straight channel, the function of which will be discussed below.  
         [0020]    The timepiece movement  10  further includes a seconds-wheel  16  fixedly secured with a seconds-shaft  16   a , to which a seconds-hand (not shown) may be fixedly secured. The seconds-wheel  16  is rotatable by a motor (not shown) as a function of second time. The seconds-shaft  16   a  is receivable within the hollow minute-shaft  14   a  for co-axial rotational movement about the axis L-L. As can be seen in FIG. 4, through the seconds-wheel  16  is provided with a small opening  16   b , the function of which will be discussed below.  
         [0021]    Returning to FIG. 1, such shows the timepiece movement  10  in which the hour-wheel  12 , the minute-wheel  14  and the seconds-wheel  16  are assembled for co-axial rotational movement about the axis L-L. A light emitter  18 , e.g. a light-emitting diode for emitting light and a light receiver  20  for receiving and detecting the light emitted by the light emitter  18  are connected with and controlled by a microcontroller unit (MCU)  30 . While a wide variety of microcontroller units are suitable for the present purpose, an appropriate microcontroller unit may be one traded by Novatek Microelectronics Corp., Ltd., of Taiwan, under Model No. NT6613.  
         [0022]    It can be seen in FIG. 1 that the light emitter  18  is positioned at the level of the openings  12   b ,  14   b  and next to the opening  14   b . Next to the opening  12   b  is provided with an optical fibre  22 , whose one end  22   a  is close to the opening  12   b  for receiving light emitted by the light emitter  18  and transmitted through the openings  12   b ,  14   b . Another end  22   b  of the optical fibre  22  is close to an upper surface  16   c  of the seconds-wheel  16 . The light receiver  20  is positioned vertically below the end  22   b  of the optical fibre  22 , for receiving the light transmitted through the optical fibre  22 .  
         [0023]    During the rotation of the seconds-wheel  16 , the opening  16   b  will be brought into rotational movement about the longitudinal axis of the seconds-shaft  16   a , which coincides with the axis L-L. The opening  16   b  is so positioned that, once every revolution of the seconds-wheel  16 , the opening  16   b  will be brought between the end  22   b  of the optical fibre and the light receiver  20 , thus providing a clear line-of-sight between the end  22   b  of the optical fibre and the light receiver  20 . When the seconds-wheel  16  is in this position, light transmitted by the optical fibre  22  can be received, and thus detected, by the light receiver  20 .  
         [0024]    During the operation of the timepiece movement  10 , the light emitted by the light emitter  18  will normally not reach, and thus not detected by, the light receiver  20 , because of blocking by the minute-shaft  14   a , and/or the hour-shaft  12   a , and/or the seconds-wheel  16 . Only when the hour-wheel  12 , the minute-wheel  14  and the seconds-wheel  16  are in the position as shown in FIG. 1 will the light emitted by the light emitter  18  be receivable and detectable by the light receiver  20 . In this particular position, the openings  12   b ,  14   b  are aligned with each other to form a continuous and straight channel next to the light emitter  18 , allowing the light emitted by the light emitter  18  to pass through in a direction perpendicular to the axis L-L, and be received by the optical fibre  22 , through its end  22   a . The light so received is transmitted via the optical fibre  22  to its another end  22   b . As, in this position, the opening  16   b  is positioned between the end  22   b  of the optical fibre  22  and the light receiver  20 , the light so transmitted by the optical fibre  22  will be transmitted through the opening  16   b  in a direction parallel to the axis L-L, and be received and detected by the light receiver  20 .  
         [0025]    The hour-hand, minute-hand and seconds-hand are arranged such that when the hour-wheel  12 , the minute-wheel  14  and the seconds-wheel  16  are in the respective position as shown in FIG. 1, the time displayed is meant to correspond to 12 o&#39;clock, 0 minute, 0 second or 24 o&#39;clock, 0 minute, 0 second. Once light is received by the light receiver  20 , a signal will be sent to the MCU  30 . The MCU  30  will then check radio signals received by a receiver (not shown) from an external source corresponding to the accurate time of the day. The signals are then compared with the time when the signal indicative of the reception or detection of light by the light receiver  20 . Corrective actions are then carried out to bring the hour-hand and/or the minute-hand and/or the seconds-hand to the respective correct position to show the correct time of the day, as is well known in the conventional manner. For example, if when the hour-wheel  12 , the minute-wheel  14  and the seconds-wheel  16  are in the respective position as shown in FIG. 1, i.e. when the hour-hand, the minute-hand and the seconds-hand are aligned, the actual time is 1 o&#39;clock, the MCU  30  will generate 60×60 (3,600) pulses (each pulse representing one second) to drive the hour-hand, the minute-hand and the seconds-hand to the 1 o&#39;clock position.  
         [0026]    Turning to FIG. 5, a block diagram of an exemplary microcontroller unit  100  appropriate for use as the MCU  30  in the timepiece movement  10  is shown. The unit  100  includes, among other components:  
         [0027]    a. a central processing unit (CPU) core  102 , containing the following function blocks: program counter, arithmetic logic unit (ALU), carry flag, accumulator, table branch register, data pointer and stack;  
         [0028]    b. a 4096×16 bit read-only-memory (ROM)  104 ;  
         [0029]    c. a random access memory (RAM)  106 , containing general-purpose data memory, liquid crystal display (LCD) RAM, and system registers;  
         [0030]    d. an oscillator module  108 , with two on-chip oscillation circuits OSC and OSCX;  
         [0031]    e. an 8-bit timer  110 , which consists of an 8-bit up counter and an 8-bit preload register. The timers provide programmable internal timer function and read the counter values; and  
         [0032]    f. a programmable sound generator (PSG)  112 ;  
         [0033]    It can be seen that the present invention includes at least the following advantages over the prior art arrangements. As the gap between the hour-shaft  12   a  and the minute-shaft  14   a  is very small, when compared with the gap between the hour-wheel and the minute-wheel, light refraction loss is thus minimized. As the optical fibre  22  is bendable, it makes possible the alignment of shafts and gears in different positions of the timepiece movement  10 . Only a single light beam is used for alignment of the hour-hand, the minute-hand and the seconds-hand, and only one set of light emitter and light receiver is used.  
         [0034]    The present invention also allows pre-set alarm function, in which a user may program the MCU  30 , to cause the timepiece to generate an alarm, e.g. sound, at a certain pre-determined time, e.g. 3 o&#39;clock, every day.  
         [0035]    It should be understood that the above only illustrates an example whereby the present invention may be carried out, and that various modifications and/or alterations may be made thereto without departing from the spirit of the invention. For example, while the invention is explained above with reference to a timepiece with an hour-shaft, a minute-shaft and a seconds-shaft, it is equally applicable to a timepiece with an hour-shaft and a minute-shaft only.  
         [0036]    It should also be understood that various features of the invention which are, for brevity, described here in the context of a single embodiment, may be provided separately or in any appropriate sub-combinations.