GB1602034A - Calendar timepiece - Google Patents

Description

(54) CALENDAR TIMEPIECE (71) We, CITIZEN WATCH CO., LTD., a Japanese corporate body of 2-1-1, Nishishinjuku, Shinjuku-ku, Tokyo, Japan do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement:- This invention relates to a calendar timepiece, particularly to a portable timepiece provided with hands, which has a device for automatically correcting the last date of the month.

Heretofore, most hand display electronic timepieces and mechanical timepieces have to be manually corrected in the calendar mechanism at the last day of a month with less than 31 days. It is often forgotten and troublesome for a user to correct the calender display of his watch at the end of the month. In order to prevent this inconvenience, there has been proposed a mechanism in which the discrimination of the month less than 31 days and the month of 31 days is mechanically made by means of a cam, etc. However, this mechanism is complicated since many parts such as wheels and cams have to be increased.

Therefore, the mechanism is not suitable for a portable timepiece which is desired to be made and miniaturized.

Of course, all mechanical timepieces have to put up with such complicated mechanism. However, in an electronic timepiece such as the crystal oscillator type watch recently developed, automatic correction of the last date of the month can be simply and precisely attained by means of a structure which automatically corrects the end of the month in accordance with electrical signals.

An object of the invention is to provide a calendar timepiece in which the above described defects are eliminated.

In accordance with the invention there is provided a calendar timepiece comprising: a) a means for generating a time reference signal: b) a driving means for operating in response to said time reference signal; c) an analogue time display device driven by said driving means through a first transmission mechanism; d) a date dial plate arranged to advance by one step every time said time display device advances by 24 hours so as to change a date display of said time display device; e) a date detecting means arranged to produce a date signal changed every 24 hours in accordance with said time reference signal; f) a month detecting means arranged to detect the last date of each month having days less than 31 days in accordance with said date signals and produce a signal for the end of each such month; and g) a means for automatically correcting a date indication at the end of each month having less than 31 days and operative in response to coincidence of signals produced by said month detecting means and by said date detecting means to advance said date dial plate so as to display the first date of the next month; said means for automatically correcting a date indication at the end of each month having less than 31 days comprising a mechanical coupling means for coupling said date dial plate with said driving means through a second transmission mechanism upon said coincidence of signals so that said date dial plate is advanced in steps of one day, and detecting means for detecting the number of steps advanced by the date dial plate, whereby after the date dial plate has been advanced by the number of steps corresponding to the signal produced by the date detecting means said mechanical coupling means uncouples said second transmission mechanism from said driving means.

According to an advantageous feature of this invention the calendar timepiece is automatically corrected at the last date of the month less than 31 days, inclusive of February in a leap year.

An advantage of this invention is that power consumption for correcting the last date of the month less than 31 days is minimised.

Embodiments of the invention are hereinafter described by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a block diagram showing a calendar timepiece of an embodiment according to this invention Fig. 2 is a plan view in a brief part of a calendar timepiece of an embodiment according to this invention; Fig. 3A and 3B are sectional views to explain the operation of a correction mechanism according to this invention Fig. 4 is a block diagram of a correction control circuit according to another embodiment of this invention; and Fig. 5 is a plan view of a date correction mechanism of Fig. 4.

Fig. 1 is a block diagram showing a system of a calendar timepiece according to this invention, in which reference numeral 101 depicts an ordinary electric timepiece block including an oscillator 1, a frequency divider 2, a converter 3, hands 4, 5, 6, a date dial plate 7 and a day dial plate 8. Reference numeral 102 denotes a block for generating a signal which automatically corrects the end of the month and 103 a block for correcting the last day of the month less than 31 days. The block 102 includes a date counter 9 which detects, for example, a signal of one second delivered from the frequency divider 2 to generate a counting pulse. A decoder 10 reads out the date from the output of the date counter 9.If the contents of the decoder 10 are signals of S28, S2g, Sic or S31 corresponding to dates 28, 29, 30 and 31, they are detected by a date detector 11 and a detection signal is transmitted to AND gate 28, AND gate 29, AND gate 30, or OR gate 13, respectively.

Each time a signal arrives at an input of OR gate 13 a detection signal 03t is delivered to a month counter 14 composed of a counter carried up every 12 bits; also, the date counter 9 is reset by a signal on a line 19. As a result, the count value is advanced by one in the month counter 14. The count content of the month counter 14 is decoded by a decoder 15. A month detector 16 detects months less than 31 days, i.e: February, April, June, September and November among the contents of the decoder 15 and delivers a detection signal 030 on line 18' through OR gate 17 to AND gate 30.Therefore, if there is delivered a signal h, corresponding to a month less than 31 days from OR gate 17 and a signal corresponding to 30 days is transmitted to AND gate 30 from date detector 11, signal +30 is transmitted from AND gate 30 and further delivered through OR gate 13 to the month counter 14.

When the month detector 16 detects February, an output signal is delivered on a line 18 so that when the date detector 11 detects 28th day, a signal 028 is delivered from AND gate 28 to the month counter 14 through OR gate 13.

In a leap year, an output signal is transmitted from leap year counter 20 composed of a counter carried up every four bits, this signal being transmitted to AND gate 29. Thus, when the month detector 16 detects February and the date detector 11 detects 29th day the above three signals are delivered to AND gate 29 which delivers the signal 029 to the month counter 14 through OR gate 13. The output signal from leap year counter 20 is also transmitted to AND gate 28 through an invertor 44 whereby this gate is inhibited.

The signals 028, 029, 030 of the end of the month less than 31 days are delivered to a control circuit 40 respectively so that the control circuit 40 turns on, e.g., a transistor 42, to cause a current to flow through a coil 41 whereby the control circuit 40 effects date correction in correspondence with the signals #28 028, 029, 030 respectively. When the coil 41 is energized, a mechanism 43 for correcting the date at the end of the month is operated so as to be driven from the converter 3 by the driving system of the hour hand 6, date dial plate 7 and day dial plate.

The correction of the date is detected by means of a detector 45 which produces a detection signal which is fed back to the correction control circuit 40 so that transistor 42 turns off. Thus date correction is effected in correspondence with the date correction signal 028, 029s or 030. This correction is described in greater detail below.

The date counter 9 is reset by means of a reset switch 47 and a correction switch 46 is turned on and off by the number of the date dial plate 7 so that the contents of the date counter 9 are in accord with those of the date dial plate 7.

Fig. 2 is a plan view of the end of the month correction mechanism 43 and the ordinary date advancing mechanism. In the ordinary date advancing mechanism, ordinary date advancing is effected such that a clutch wheel 50 of the hour 6 rotates a date wheel 53 through a date transmission wheel 52 and a small wheel 52a fixed to the wheel 52. Then, a pin 55 provided on the date wheel 53 rotates a date dial 7 and a pin 56 provided on the date wheel 53 revolves a day transmission wheel 57 so as to rotate a daily star wheel 58 which rotates day dial 8, and as the result, the correction of both the day and the date is effected. Reference numerals 59 and 60 depict clutch wheels, 61 depicts a date transmission wheel, 62 a date wheel, and 63 a spring, which together constitute the end of the month correction mechanism 43.This structure will be described in greater detail with reference to Figs. 3A and 3B along with Figs. 1 and 2.

When one of the signals 0285 029' 030 is delivered to the correction control circuit 40 the transistor 42 turns on and thereby the coil 41 is energised and as a result magnetises a ferromagnetic core 71. The clutch wheel 60 made of a magnetic material is usually separated from the clutch wheel 59 by means of the spring 63 as shown in Fig. 3A. When the coil 41 is energised, the clutch wheel 60 is attracted by the core 71 so as to be engaged with the clutch wheel 59, Fig. 3B and thereby the date transmission wheel 61 is rotated. Thus, the date wheel 62 is rotated so that the date dial plate 7 is advanced. The number of days by which the date wheel 62 is advanced is detected by means of the detector 45 which thus detects the number of days by which the date dial 70 is advanced.A signal from the detector 45 is transmitted to the correction control circuit 40. As shown in Figure 2, the detector 45 comprises a switch which is operated by the date wheel 62 to produce a pulse each time the wheel 62 advances by one step to advance the date dial plate 7 by one day.

The block 103 operates as follows.

Assuming a signal 028 corresponding to 28th day of February arrives at the correction control circuit 40, the circuit 40 energises coil 41 four times through the transistor 42 and the date dial plate 7 is advanced four days. The detector switch 45 transmits four pulses to the circuit 40 so that after the transistor 42 has been turned on four times further turning-on of the transistor is prevented. Thus, the calendar indicates the Ist day of March. Similarly, the signals 429, 030 cause the date dial plate 7 to be advanced by three and two days respectively. Thus, the date dial 7 is advanced by a necessary number of days in accordance with the signals )28, 029 030 corresponding to 28th date, 29th date and 30th date respectively.When the correction has been made, the signal supplied from the circuit 40 to the transistor 42 ceases so that the transistor 42 turns off and thereby the clutch wheel 60 is disengaged from the clutch wheel 59. As the result, there is completed the correction of the end of a month which has less than 31 days.

Figs. 4 and 5 show a modified embodiment of the invention in which the same blocks 101, 102 are provided and only a modified correction control circuit 203 is shown. In Fig. 4 reference numeral 141 depicts an OR gate to which date correction signals 028 029s 030 are respectively delivered from AND gates 28, 29, 30 (See Fig. 1).The number of the date to be corrected is thus determined bv the date correction signals 028s 029, 030- For example, when the signal pub is delivered from AND gate 28 (see Fig. 1) to OR gate 141 of the correction control circuit 203, a signal appears on a line 142 so as to reset a counter~143 and a shift register 144 simultaneously. Thus, the shift register 144 is reset so that the potential of a line 145 becomes high and thereby a driving signal of one second is transmitted from AND gate 146 to a coil 147, and at the same time the shift register 144 is shifted.

In this embodiment a plurality of driving pulses may be used to engage and disengage the mechanical connection between the end of month correcting mechanism 150 and the ordinary date advancing mechanism. The number of pulses is determined by the design of the mechanism 150, that is the number of the teeth of a ratchet wheel 213, Figure 5, and the number of projections 212a of a cam 212 corresponding thereto. In the following description it is assumed that three pulses need to be applied to the coil 147 for engagement or disengagement of the correcting mechanism 150. Thus, the shift register 144 is constructed so that, after three pulses of one second have been transmitted by the AND gate 146, the potential of the line 145 becomes low so that the signal of one second is stopped.

It is to be noted that, although it has been assumed that three pulses need to be applied to the coil 147 for engagement or disengagement of the correcting mechanism 150, Figure 5 of the drawings shows the ratchet wheel 213 as having 24 teeth. Thus, in the construction shown, only two pulses are required to engage or disengage the mechanism 150 since there are six projections 212a on the cam 212. When three pulses are used, as described, the ratchet wheel 213 would need to have 36 teeth.

The date correction mechanism 150 is thus engaged with the timepiece wheel train to advance the date dial 7 and a switch 151 is closed upon each advance by one date of the date dial whereby the counter circuit 143 is applied with a signal. In the case that there is displayed February 28, the switch 151 is turned on and off four times so that the date dial 7 (see Figure 1) is advanced by four dates and thereby the first date of the next month is displayed. In this case, the counter 143 counts numeral "4" so that the potential on line 161 becomes high and thereby signal 028 is transmitted from AND gate 152 and thus from OR gate 165. Then, one pulse signal is transmitted from AND gate 166 and thereby the shift register 144 is reset again.Thus, AND gate 146 is opened to again apply a driving signal of three pulses to the coil 147 whereby the date correction mechanism 150 is disengaged from timepiece wheel train. As the result, the correction of the end of the month of February is completed. This operation is described in greater detail below.

Similarly, the signal 02Y is delivered to the counter 143 so that the counter 143 counts numeral "3". When the potentials on lines 162, 163 becomes high, the output signal is transmitted from AND gate 153 so that the coil 147 is applied with a driving signal.

Furthermore, in case of signal 030 the counter 143 counts numeral "2" to obtain the output from AND gate 154 and thereby applies a driving signal to the coil 147 and as the result, required date correction can be effected. Switches 46 and 47 (Fig. 1) are used to correct the content of the date counter. In addition, it is possible to adjust date, month and year by separately accommodating a setting switch into a month counter of a counter carried up every 12 bits and a year counter of a counter carried up every 4 bits.

There is now described in greater detail the operation of the date correction mechanism 150 with reference to Fig. 5 together with Fig. 4. Reference numeral 7 depicts a date dial, 202 an hour hand clutch wheel, 203 a date transmission wheel, 204 the ordinary date advancing wheel, 205 a daily star wheel which constitute a conventional date dial advancing apparatus.

The date advancing apparatus of this invention for automatically making a correction at the end of the month comprises a coil 147, cam member 212, ratchet wheel 213 ratchet lever spring 214, engaging wheel 215, engaging lever 216, transmission wheel 218 and date advancing wheel 219. The date feeding apparatus and the circuit of Fig. 4 constitute an apparatus requiring no manual attention at the end of the month.

In Fig. 4, the signal 028 corresponding to February 28 is delivered to the coil 147, and three pulses of one second are transmitted to the coil 147 so that the coil 147 attracts the ratchet lever spring 214 to the centre of the coil 147 three times. Each time this attraction of the ratchet lever spring 214 is released, the spring advances the ratchet wheel 213 by one tooth thereof. The three pulses are applied to the coil 147 so that the ratchet wheel 213 is advanced by three teeth. The cam 212 is rotated with the wheel 213 so that a projection 212a of the cam engages the shaft 215a of an engaging wheel 215 to cause the wheel 215 to engage with clutch wheel 202 and with transmission wheel 218, the shaft 215a being carried by a lever 216 biassed counterclockwise by a spring 216'.Thus, the hour hand clutch whee 202 drives the date advancing wheel 219 to advance the date dial 7 for correction of the last date of the month.

In the case that the signal 028 is delivered to OR gate 141 to effect date advancing of four days, the switch 151 turns on and off four times and thereby pulses are transmitted to the counter 143. The counter 143 counts numeral "4" so that a high potential signal appears on the line 161.

Thus required date correction is completed in such operation of the circuit as set forth above so that the shift register 144 is reset and thereby three pulses of one second, as a set signal, which functions to disengage wheel 218, are delivered to the coil 147. The cam 212 is thus rotated so that the shaft 215a of the engaging wheel 215 falls into a groove of the cam 212 under the action of a returning force provided by the spring 16'.

As the result, the wheels 218, 219 for correcting the end of the month are disengaged from the hour hand clutch wheels 202.

As set forth above, this invention enables that there may be automatically corrected the last day of the month shorter than 31 days inclusive of a leap year, by electrically synthesizing a signal for instructing the correction of the end of the month and by mechanically engaging the end of the month correction mechanism with the ordinary hand driving system. Therefore, there is not required any converter such as motor to correct the end of the month and as the result, this invention is particularly effective in case that it is required to minimise the size of a wristwatch and to make it thin.

Further, this invention provides an advantage of reducing power consumption since the cam 212 is driven by a driving current of one or several pulses only on the month shorter than 31 days.

WHAT WE CLAIM IS: 1. A calendar timepiece comprising; a) a means for generating a time reference signal; b) a driving means for operating in response to said time reference signal; c) an analogue time display device driven by said driving means through a first transmission mechanism; d) a date dial plate arranged to advance by one step every time said display device advances by 24 hours so as to change a date display of said time display device; e) a date detecting means arranged to produce a date signal changed every 24 hours in accordance with said time reference signal; f) a month detecting means arranged to detect the last date of each month having days less than 31 days in accordance with

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   pulses to the coil 147 whereby the date correction mechanism 150 is disengaged from timepiece wheel train. As the result, the correction of the end of the month of February is completed. This operation is described in greater detail below.

   Similarly, the signal 02Y is delivered to the counter 143 so that the counter 143 counts numeral "3". When the potentials on lines 162, 163 becomes high, the output signal is transmitted from AND gate 153 so that the coil 147 is applied with a driving signal.

   Furthermore, in case of signal 030 the counter 143 counts numeral "2" to obtain the output from AND gate 154 and thereby applies a driving signal to the coil 147 and as the result, required date correction can be effected. Switches 46 and 47 (Fig. 1) are used to correct the content of the date counter. In addition, it is possible to adjust date, month and year by separately accommodating a setting switch into a month counter of a counter carried up every 12 bits and a year counter of a counter carried up every 4 bits.

   There is now described in greater detail the operation of the date correction mechanism 150 with reference to Fig. 5 together with Fig. 4. Reference numeral 7 depicts a date dial, 202 an hour hand clutch wheel, 203 a date transmission wheel, 204 the ordinary date advancing wheel, 205 a daily star wheel which constitute a conventional date dial advancing apparatus.

   The date advancing apparatus of this invention for automatically making a correction at the end of the month comprises a coil 147, cam member 212, ratchet wheel 213 ratchet lever spring 214, engaging wheel 215, engaging lever 216, transmission wheel 218 and date advancing wheel 219. The date feeding apparatus and the circuit of Fig. 4 constitute an apparatus requiring no manual attention at the end of the month.

   In Fig. 4, the signal 028 corresponding to February 28 is delivered to the coil 147, and three pulses of one second are transmitted to the coil 147 so that the coil 147 attracts the ratchet lever spring 214 to the centre of the coil 147 three times. Each time this attraction of the ratchet lever spring 214 is released, the spring advances the ratchet wheel 213 by one tooth thereof. The three pulses are applied to the coil 147 so that the ratchet wheel 213 is advanced by three teeth. The cam 212 is rotated with the wheel 213 so that a projection 212a of the cam engages the shaft 215a of an engaging wheel 215 to cause the wheel 215 to engage with clutch wheel 202 and with transmission wheel 218, the shaft 215a being carried by a lever 216 biassed counterclockwise by a spring 216'.Thus, the hour hand clutch whee 202 drives the date advancing wheel

   219 to advance the date dial 7 for correction of the last date of the month.

   In the case that the signal 028 is delivered to OR gate 141 to effect date advancing of four days, the switch 151 turns on and off four times and thereby pulses are transmitted to the counter 143. The counter

   143 counts numeral "4" so that a high potential signal appears on the line 161.

   Thus required date correction is completed in such operation of the circuit as set forth above so that the shift register 144 is reset and thereby three pulses of one second, as a set signal, which functions to disengage wheel 218, are delivered to the coil 147. The cam 212 is thus rotated so that the shaft 215a of the engaging wheel 215 falls into a groove of the cam 212 under the action of a returning force provided by the spring 16'.

   As the result, the wheels 218, 219 for correcting the end of the month are disengaged from the hour hand clutch wheels 202.

   As set forth above, this invention enables that there may be automatically corrected the last day of the month shorter than 31 days inclusive of a leap year, by electrically synthesizing a signal for instructing the correction of the end of the month and by mechanically engaging the end of the month correction mechanism with the ordinary hand driving system. Therefore, there is not required any converter such as motor to correct the end of the month and as the result, this invention is particularly effective in case that it is required to minimise the size of a wristwatch and to make it thin.

   Further, this invention provides an advantage of reducing power consumption since the cam 212 is driven by a driving current of one or several pulses only on the month shorter than 31 days.

   WHAT WE CLAIM IS: 1. A calendar timepiece comprising; a) a means for generating a time reference signal; b) a driving means for operating in response to said time reference signal; c) an analogue time display device driven by said driving means through a first transmission mechanism; d) a date dial plate arranged to advance by one step every time said display device advances by 24 hours so as to change a date display of said time display device; e) a date detecting means arranged to produce a date signal changed every 24 hours in accordance with said time reference signal; f) a month detecting means arranged to detect the last date of each month having days less than 31 days in accordance with

   said date signal and produce a signal for the end of each such month; and g) a means for automatically correcting a date indication at the end of each month having less than 31 days and operative in response to coincidence of signals produced by said month detecting means and by said date detecting means to advance said date dial so as to display the first date of the next month; said means for automatically correcting a date indication at the end of each month having less than 31 days comprising a mechanical coupling means for coupling said date dial plate with said driving means through a second transmission mechanism upon said coincidence of signals so that said date dial plate is advanced in steps of one day, and detecting means for detecting the number of steps advanced by the date dial plate, whereby after the date dial plate has been advanced by the number of steps corresponding to the signal produced by the date detecting means said mechanical coupling means uncouples said second transmission mechanism from said driving means.
2. 2. A calendar timepiece as claimed in Claim 1 wherein said mechanical coupling means comprises an electro-magnetic actuator energized in response to said coincidence of signals for the end of the month and a clutch wheel coupling said date dial plate with said driving means through said second transmission mechanism when said electro-magnetic actuator is energized.
3. 3. A calendar timepiece as claimed in Claim 1 or Claim 2 wherein said mechanical coupling means comprises an electromagnetic actuator energized by a plurality of pulses generated at the end of each month having less than 31 days in response to said coincidence of signals, a ratchet device provided with a ratchet wheel rotating stepwise upon every energization of said electro-magnetic actuator, and a cam device driven by said ratchet wheel and operative to couple said driving means to said date dial plate through said second transmission mechanism when said ratchet wheel rotates through a predetermined angle.
4. 4. A calendar timepiece as claimed in claim 1, comprising a year counter driven by said month detecting means, said year counter being carried up every four bits to produce a signal for the end of the month corresponding to 29th date every four years for the last day of February, so that the calendar is corrected at the end of February in a leap year.
5. 5. A timepiece having a calendar mechanism substantially as hereinbefore described with reference to the accompanying drawings.