Abstract:
An electronic timepiece having a calendar mechanism for displaying a date or date and day includes circuitry for detecting the timing or the movement of the calendar mechanism and for generating a detecting signal. The timepiece also includes means for controlling the electric power supplied to energizing means for the calendar mechanism when the detecting signal is supplied.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to an electronic timepiece with a calendar mechanism which is improved by preventing a decrease in the accuracy of the subject timepiece at the time of operation of the calendar mechanism. 
     In the timepieces with a calendar mechanism power for energizing the calendar mechanism is great in comparison with the power used to energize the timepiece movement. In the case of a completely balanced timepiece, this causes a decrease in accuracy due to the reduction in the amplitude of available power when using a step-motor drive, the deviation from the normal position of the rotor, results frequently in the movement. Such tendencies will increase in those timepieces having the function of displaying both day and month or having a quick or early operation of the calendar display. 
     SUMMARY OF THE INVENTION 
     An object of this invention is to provide an electronic timepiece having a calandar mechanism which is so improved that the timepiece movement is subjected to substantially no influences due to the operation of the calendar mechanism. 
     An electronic timepiece according to this invention essentially comprises means for detecting the operation of the calendar mechanism and means for controlling the electric power supplied to the calendar mechanism when the signal from the detecting means is supplied thereto. The detecting means can operate to generate a signal by detecting the timing of the start of the calendar mechanism or by sensing that the power for energizing the calendar mechanism reaches a predetermined value. 
     Other objects and advantages of this invention will be more fully understood from the following description taken in connection with the accompanying drawings. 
    
    
     In the drawings: 
     FIG. 1 is a schematic front view of a timepiece embodying this invention; 
     FIG. 2 is a schematic rear view of the timepiece shown in FIG. 1; 
     FIG. 3 is a partial section of the timepiece shown in FIGS. 1 and 2; 
     FIG. 4 is a plan view of a calendar wheel, in enlarged scale, used in the timepiece shown in FIGS. 1 to 3; 
     FIG. 5 is an electric circuit diagram of a circuit used in the timepiece of this invention; 
     FIG. 6 is a block diagram of an alternative circuit used in the timepiece of this invention; and 
     FIG. 7 is a diagram showing how the circuit of FIG. 7 modifies pulses. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As seen in FIGS. 1 and 2, a timepiece includes the following elements: a substrate 1, an electric battery cell 2, a crystal oscillator 3, an IC circuit block 4 including oscillating, frequency dividing and dividing circuits and an electric-mechanical transducer 5 having a rotor 5a and a coil 5b. A second wheel 6 is driven by the rotor 5a via a gear train to rotate one revolution every minute and a calendar wheel 7 is driven by the second wheel 6 through a gear train to rotate one revolution by 24 hours. A lever 9 biased by a spring 10 serves as a detent to retain the position a calendar plate 11. 
     As shown in FIGS. 3 and 4, a shaft 1b is journaled on the substrate 1 within an insulating bushing 1a to electrically isolate the shaft and substrate. The calendar wheel 7 is made of an insulating material such as plastic and is supported on the shaft 1b with a metal bushing 7a. A switch shaft 7b projects from the calendar wheel 7 and connects with the bushing 7a via a lead plate 7c. A spring lever 8 having a driving pawl 8a and two spring arms 8b and 8c is supported rotatably on the calendar wheel 7 and held by a rivet 7d. 
     In the normal state, the spring lever 8 is positioned so that the arms 8b and 8c surround a boss 7e of the calendar wheel 7, as shown by the solid line in FIG. 4. When the pawl 8a is subjected to a driving force acting in the direction shown by an arrow 12, the arm 8b is resiliently deformed and when the force increases over a predetermined, amount the arm 8b is more deformed and contacts the switch shaft 7b. 
     On the other hand, when the pawl 8a is pressed in the opposite direction of the arrow 12 at the time, for example, of quick revolution of the calendar plate 11, the other arm 8c is deformed as shown by the two dotted chain in FIG. 4. 
     The pawl 8a of the spring lever 8 acts to rotate the calendar plate 11 against the detent action of the lever 9 and, in this stage, if the load or torque is acting to the spring lever 8, then the pawl 8a contacts the switch shaft 7b due to deformation of the arm 8b. Accordingly, if the substrate is connected to the plus terminal of a direct current source of supply, a plus signal will be sent to the circuit block 4 through a path consisting of the calendar plate 11, spring lever 8, switch shaft 7b, lead plate 7c, metal bushing 7a and shaft 1b. The pawl 8a will disconnect from the shaft 7b when the load decreases. The limit of the load is determined by the resiliency of the arm 8b and, if necessary, a suitable adjustment may be made. One of the applicable adjustment is to use as the shaft 7b a member having an eccentric head which acts to rotate the spring lever 8. When one wishes to obtain an operation so that a signal is supplied to the circuit 4 when the calendar mechanism starts to operate regardless of the size of the load, the spring lever 8 is insulated from the members other than the substrate 1 so as to obtain a signal only when the pawl 8a contacts the calendar plate 11. 
     Electrical energy for use in operation of the calendar mechanism to change the indication relating to date, day or month is supplied from a direct current source of supply to the transducer 5 under the control of controlling means after the circuit 4 is supplied with a signal in the manner as described above. 
     One of the suitable controlling means is shown in FIG. 5, in which a detector 21 utilizes an inverter 22 and two MOSTS (Metal-Oxide-Semiconductor Transistors) 23 and 24. The detecting signal of the detector is kept H during the operation of the calendar mechanism and the detector is supplied by a pair of input terminals 25. When the level of the signal is L or when the calendar mechanism is out of operation, the first MOST 23 is maintained OFF and the second MOST 24 is held ON. On the other hand, when the level of the signal is H, the first MOST 23 is turned on and the second MOST 24 turned OFF. 
     The reference numeral 26 denotes a direct current source of supply having a plus terminal 27 and a minus or ground terminal 28. A booster 30 comprises three diodes 31, 32, and 33 and three condensers 34, 35 and 36. A signal having a higher frequency than the driving cycle of the transducer 5 is supplied to a pair of terminals 37 and 38 in reverse phase to the driving cycle. 
     When the level at the terminal 38 becomes H, the first condenser 34 is charged and when the level at the other terminal 37 becomes H due to the inversion in phase, the second condenser 35 is charged at the voltage twice the terminal voltage of the first condenser 34. Accordingly, the potential at the terminal 39 becomes twice the voltage of the source. 
     A driving circuit denoted by the reference numeral 40 comprises a pair of CMOST (Complementary Metal-Oxide Semi-conductor Transistor) 41 and 42 having gates that are alternately energized once per second by the signal supplied from the frequency divider through terminals 43 and 44, respectively. 
     When the level at the terminal 25 is L, the coil 5b of the driving circuit 40 is driven at the voltage impressed between the terminals 27 and 28 which is equal to that of the source and when the level is H, or when the calendar mechanism is in operation, the driving circuit 40 is driven at the voltage twice the voltage of the source. 
     In FIG. 6 there is shown a modified controlling means which functions to elongate the width of driving pulses. The level at a terminal 50 which corresponds to the terminal 26 in FIG. 5 is kept at L and rises to H when the calendar mechanism is in operation. From output terminals denoted by 51 and 52 signals are generated which have levels that are mutually changed by two seconds. A series of flip-flop circuits 53 through 56 constitute a frequency divider. With a standard oscillator having an oscillator frequency of 32,768 KHz, the flip-flop 53 forming the 10th step generates a signal having a frequency of 32 Hz; the flip-flop 54 forms an 11th step generating a 16 Hz signal, the flip-flop 55 15th step generating 1 Hz signal and the flip-flop 56 16th step generating 0.5 Hz signal. The reference numeral 57 designates a first NAND gate for the terminal 50 and 16 Hz pulse train, 58 a second NAND gate for the terminal 50 and 32 Hz pulse trains and 59 a NOR gate for the first and second NAND gates. 
     Typical wave forms of the signals in the circuit of FIG. 6 are given in FIG. 7 wherein the letters A, B, C, D1 and D2 corresponding to the points shown in the same letters. When the level at the terminal 50 is kept at L (when the calendar mechanism is out of operation), the output of the NAND gate 58 is maintained L level and the following elements are controlled by the output of the first NAND gate 57. Accordingly, a pulse train having a duration of 1/64 second as shown by D1 in FIG. 7 is obtained from the terminals 51 and 52. 
     When the level at the terminal 50 is H (when the calendar mechanism is in operation), the output of the first NAND gate 57 becomes level L and the other elements are placed under the control of the second NAND gate 58, so that a pulse train having a duty of 1/32 second as shown by D2 in FIG. 7 is taken from the terminals 51 and 52. 
     The duration of the pulses is determined in accordance with the step of the frequency divider from which the signal is obtained, so that a driving pulse train having a desired wave form can be obtained by selecting the cycle depending on the condition of the calendar mechanism. 
     In the above embodiments, a pulse motor is used as an electric-mechanical transducer. However, another type of transducer such as a completely balanced motor or a driving mechanism used with a pallet fork and staff can be employed. 
     According to this invention, as has been stated hereinbefore, the electrical energy supplied to the calendar mechanism is increased when the power or load produced for driving the calendar mechanism increases over a predetermined value or when such a load is created, so that the undesirable effects incurred by driving the calendar mechanism, such as decreased accuracy of the timepiece movement will be eliminated. Accordingly, it is possible to introduce into a calendar mechanism a function displaying the date or month and a quick change of the function at midnight. In addition, the power consumption can be minimized since the increase in electrical energy is limited within the requisite period of time.