Abstract:
An electronic wristwatch without mechanically driven hands has an electromagnetic output which is sensed for measuring the timing rate. A modulated signal applied to the coil of an alarm sounding device produces the electromagnetic field for sensing. The display is fully illuminated while timing in order to eliminate stray electric fields.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to an electronic wristwatch of the type having no mechanically driven hands and more particularly to an electronic wristwatch of this type which outputs electromagnetic signals suitable to measure the timing rate. In the prior art, as an apparatus for measuring the timing rate, there is a device which measures the vibrational rate of a quartz crystal vibrator, which is the time standard source of a wristwatch, by means of a sound detector. The timing rate is the gain or loss in timekeeping of a wristwatch in a day. In an electronic timepiece having hands for indicating time, the timing rate is determined by measuring the magnetic field of the driving motor for the hands by means of an electromagnetic field detector. In a digital display electronic timepiece having a liquid crystal display device, the timing rate is measured by means of an electric field detector based on a 32 Hertz signal used in the AC drive on the display. Especially with a liquid display electronic timepiece, there is no apparatus for measuring the timing rate excepting instruments using an magnetic field detector or a sound detector. In recent years, a device using the above mentioned electromagnetic field detector has been popularized, and as a liquid crystal display electronic timepiece is now widely in use, it is most desirable, if not necessary to measure the timing rate by means of an electric field detector or a sound detector. Therefore, the timing rate is now measured by means of a conventional timing rate measuring device through an adapter making it necessary for the watchmaker to purchase the adapter. Moreover, as compared with an instrument using an electromagnetic field detector, the instrument using an electric field detector or an sound detector is easily influenced by external fields, noises, or the like, and accordingly measurement becomes difficult. 
     What is needed is an electronic wristwatch without mechanically driven hands which can be readily timed using conventional timing instruments which operate on electromagnetic fields. 
     SUMMARY OF THE INVENTION 
     Generally speaking, in accordance with the invention, an electronic wristwatch especially suitable for providing timing rate signals is provided. An electronic wristwatch without mechanically driven hands has an electromagnetic output which is sensed for measuring the timing rate. A modulated signal applied to the coil of an alarm sounding device produces an electromagnetic field used for sensing of timing rate. The display is fully illuminated while timing in order to eliminate stray electric fields. The modulated signal is produced upon closure of switches operated by means of an external member. The wristwatch in accordance with this invention eliminates the above-mentioned difficulties and provides a means by which the timing rate of a liquid crystal display electronic wristwatch is easily measured by using a conventional electromagnetic field detector. 
     In the field of digital display electronic wristwatches, products having an alarm function are now very popular. In such a wristwatch, if a current is applied to a coil of an alarm device, such as a loud speaker and the current has a period by which the timing rate can be measured, the required measuring apparatus is substantially the same as the apparatus for detecting the electromagnetic field of the driving motor when measuring the timing rate of an electronic timepiece having hands for time indication. With the alarm function present, the electronic magnetic field associated with the sounding device replaces the electromagnetic field of the driving motor used for hands. 
     Accordingly, it is an object of this invention to provide an improved electronic wristwatch with alarm function which can be timed using conventional electromagnetic field detectors. 
     Another object of this invention is to provide an improved electronic wristwatch with an alarm function which provides a distinctively modulated signal for use in timing. 
     A further object of this invention is to provide an improved electronic wristwatch with alarm which provides timing signals upon actuation of an external member. 
     Still another object of this invention is to provide an improved electronic wristwatch which illuminates the entire liquid display during timing so that stray electric fields are eliminated. 
     Still other objects and advantages of this invention will in part be obvious and will in part be apparent from the specification. 
     The invention accordingly comprises the features of construction, combination of elements, an arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a fuller understanding of the invention, references is had to the following description taken in connection with the accompanying drawings, in which: 
     FIG. 1 is a circuit drawing of an electronic wristwatch with alarm function in accordance with this invention; and 
     FIG. 2 is a circuit portion used in conjunction with a circuit of FIG. 1 to provide concurrent illumination of all segments of display. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The electronic wristwatch in accordance with this invention is described in detail with reference to the drawings as follows: FIG. 1 shows an exemplary circuit diagram in accordance with this invention. A timepiece includes an oscillator circuit 1, a divider circuit 2 for dividing down the signal applied from the oscillator circuit 1, a counter circuit 3 for counting timekeeping signals from the divider 2, an alarm setting counter 5, which stores data representative of the time at which the alarm should be sounded, a coincidence circuit 4, which determines whether or not the contents of the counter circuit 3 coincides with the contents of the alarm setting counter 5, and a circuit 16 for receiving the chattering inputs of switches 17, 18, 19 and for forming smoothed-out control signals for the timepiece. Further elements of the timepiece are shown in FIG. 2 and are discussed more fully hereinafter. The switches 17, 18, 19 cooperate with an external member or members which are manipulated to operate the switches. In FIG. 1, signals and circuits which are necessary to control the timekeeping and supplemental function of the wristwatch in accordance with this invention are omitted and not described in detail here except those signal and circuits particularly related to this invention. All of the circuit portions which are not described in detail here are conventional. 
     AND gate 6 comprises a first modulation signal producing circuit. The modulation signal is produced using a 1 Hz signal and a 8 Hz signal from the divider circuit 2. When the logical level of the output signal from the coincidence detector is high, the AND gate 6 outputs a signal which is a combination of the 1 and 8 Hz signals. This output signal is input to an AND gate 11 through an OR gate 10 and is modulated to be a 4 kilohertz signal by the AND gate 11. Thus, the alarm sound which is intermittenly emitted at an 8 Hz repetition rate every one second with a high pitched tone of 4 kilohertz is produced at the output of AND gate 11. 
     A D-type flip-flop 8 and AND gate 9 comprise a second modulation producing circuit. A control circuit which controls the second modulation signal producing circuit includes a D-type flip-flop 15 and AND gate 7. When switches 17, and 18 are closed at the same time by the operation of an external member (not shown), a clock signal is input at the C terminal of the D-type flip-flop 15, and the logical level at the output Q of the flip-flop 15 becomes high. As a result, blockage of the AND gate 7 is released, and the 1 Hz signal, output of the divider 2, that is the other input to the AND gate 7, is outputted from the AND gate 7. The 1 Hz output of the gate 7 then is applied to the data input D of a D-type flip-flop 8. A 32 Hz output signal from the divider circuit 2 is applied as the clocking input C to the D-type flip-flop 8. A reverse of the 1 Hz signal which is applied to the data input D is output at the Q terminal of the D-type flip-flop 8 with a 1/32 second delay. When the 1 Hz signal of the data input D and the output Q of the flip-flop 8 are applied to an AND gate 9, the second modulation signal is obtained. This signal has a 1/32 of a second pulse width with a period of 1 second. This second modulation signal and the first modulation signal produced in the AND gate 6 are applied as inputs to an OR gate 10, and the output of the gate 10 is applied as one input to an AND gate 11. The four kilohertz output of the divider circuit 2 is applied to the other input to the AND gate 11 to provide a driving signal at the output of the AND gate 11. 
     This driving signal is applied to the base electrode of a npn-type transistor 12, and the transistor 12 is switched on and off by the 4 kilohertz signal, whereby a sound generating device 13 is driven and emits a sound. 
     When an electromagnetic field detector in a timing rate measuring device 14 is used while the transistor 12 is being switched on and off, a signal can be picked up by electromagnetic induction between the electromagnetic field detector 14 and the coil 24 used in the sound generating device 13. Thus, the timing rate can be easily measured. The pulse width of the second modulation signal may have an arbitrary value. However, if the pulse width is wider than necessary for detection, power consumption is increased and a malfunction may be caused by the voltage drop during generation of the second modulation signal. A pulse width of less than 1/16 seconds is found to be suitable. Moreover, the period of the second modulation signal is also arbitrary, but a period less than 10 seconds is preferred so as to shorten the time used in measuring the timing rate. 
     When it is not necessary to measure the timing rate, the switch 19 is pushed by operation of an external member. By doing so, a signal is supplied to the reset terminal R of the D-type flip-flop 15 by way of the circuit 16 for preventing and controlling chattering. When the reset signal is applied, the logical level of the output Q of the flip-flop 15 becomes low. As a result, the 1 Hz signal of the divider output is blocked by the AND gate 7, so that the second modulation signal is not produced. 
     As described above, a signal necessary for measurement of the timing rate is easily produced. Because a conventional timing rate device can detect a 10 second signal or a one second signal to measure the timing rate, the timing rate of this wristwatch is easily measured by a conventional timing rate measuring device using an electromagnetic field detector. This is possible if the alarm, which is the sound generating device is driven by the second modulating signal described above. Accordingly, when checking performance of an electronic wristwatch without a driving motor, an adaptor, or similar device need not be installed on a timing rate measuring device, and the timing rate can be measured in the conventional manner. 
     In accordance with this invention, either an electromagnetic type or a piezoelectric type device can be adapted to work in an alarm function as the sound generating device. Furthermore, the timing rate can be measured not only by using an electromagnetic field detector but also by using a sound detector. 
     If all of the segments (not shown) of a display are lit at the time of measuring the timing rate, the timing rate can be readily measured by using an electric field detector because no segment of the display is flickering. If the display is flickering or portions of the display are flickering, the driving signal for making the display flicker is detected along with the 32 Hz modulating signal because flickering of the display is accomplished by periodically reversing one electric potential of the liquid crystal display device. Thus, the electric field detector senses an electric field caused by a 32 Hz signal used for an AC drive which is applied to the electrodes of the liquid crystal display device. Moreover, with this structure, a test whether all of the segments are lit or not can be made. Therefore, all three kinds of detectors which are now in general use can be used at the time of measuring the timing rate of a wristwatch in accordance with this invention when the circuit as shown in FIG. 2 is included. The measuring technique using an electromagnetic field detector, namely the easiest measuring method, is possible because of the 1 Hz signal applied from the sound generating device. 
     FIG. 2 shows a circuit which has been described above for lighting all of the segments. A decoder circuit 20 converts each output T of the counters 3 into a segment signal necessary for display. An OR gate 22 when driven causes every segment to be illuminated in a segment driving circuit and display device 21. The lead 23 of FIG. 2 is connected to the signal lead 23 of FIG. 1. Because the logical level of the signal 23 becomes high, as stated above, when switches 18, 19 are closed, the logical level of all of the outputs is made high by means of the OR gate 22 regardless of the segment signals for any numeral, which signals are applied from the decoder 20. Thus the signal on lead 23 overrides the signals from the decoder 20. The output signals of the timekeeping counter 3 are fed to the decoder 20. By adding a very simple circuit, the timing rate measurement and testing of whether all the display segments are lit or not are easily performed simultaneously. 
     Adoption of this invention has a great effect on the post sales servicing of the wristwatch. For a user, it is possible to use the sound which is generated from the sound generating device at the time of measuring the timing rate as one supplemental function, e.g. a pacemaker. The usefulness of the wristwatch as a product is increased by this simple circuit structure. 
     When this invention is applied to an analog timepiece not having a seconds hand where it normally takes considerable time to measure the timing rate in the conventional manner and where the interval of time between advances of the minute hand is long, rapid measurement of the timing rate is possible. Thus, this invention can also be applied to an analog timepiece. 
     It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above construction without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. 
     It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.