Electronic timepiece with stop watch

An electronic timepiece comprises a first time counting circuit including a time counter and adapted to count reference clock signals of an oscillator as time data at all times, and a time interval counting circuit provided independently of the time counting circuit and adapted to perform the function of a stopwatch based on a time count start instruction and time count stop instruction. The timepiece further includes a control circuit in which a minute/hour data and a date data are selectively displayed by the operation of a first switch on a digital type indicator and when the timepiece functions as a stopwatch a time interval data is displayed by the operation of a second switch on the indicator based on the time count start instruction and time count stop instruction. The control circuit has additional functions that, while the timepiece functions as a stopwatch, a normal minute/hour data from the time counting circuit can be switched by the operation of the first switch to a minute/hour time interval data (stopwatch) for display on the indicator and after display of the minute/hour time interval data a time interval data corresponding to a second or less can be displayed by the operation of the first switch on the indicator.

BACKGROUND OF THE INVENTION 
This invention relates to a date display type electronic timepiece capable 
of functioning as a stopwatch. 
With the advent of a digital display type electronic timepiece a variety of 
compact wristwatches of such type have been devised. Such wristwatches are 
adapted to display time data corresponding to minutes and hours on a 
display section made of a liquid crystal, LED etc. An attempt is made to 
display a date data on the display section. In this case, a date data is 
displayed on the display section by the operation of a display changeover 
switch. An attempt is also made to incorporate, in addition to such 
functions, other functions such as the function of a stopwatch into the 
wristwatches. It is necessary in this case to give a time count start 
instruction and time count stop instruction and display an involved time 
interval on the display section. Such a time interval needs to be 
displayed on a time or date display section in view of a limited display 
space. When the wristwatch performs the function of a wristwatch, if a 
long time interval is involved, there arises a necessity for reading a 
normal time data on the same wristwatch. As a result, many change-over 
switch mechanisms are required to effect a time count control and display 
changeover control, providing a bar to the miniaturization of the 
wristwatch. 
It is accordingly the object of this invention to provide an electronic 
timepiece which can readily and effectively perform a date display 
function and a stopwatch function selectively, and also normal as 
corresponding time data on the same display section, as required, through 
the control of two switches. This is a great merit when the timepiece is 
made compact as in the case of a wristwatch. 
SUMMARY OF THE INVENTION 
According to this invention there is provided an electronic timepiece 
comprising on oscillator for generating reference clock signals; a 
frequency divider for frequency dividing the reference clock signals from 
the oscillator to generate time counting signals; a time counting circuit 
including a calender data counter and adapted to count at all times the 
time counting signals of the frequency divider as a normal time data; a 
time interval counting circuit provided independently of the time counting 
circuit and adapted to perform the function of a stopwatch based on a time 
count start instruction and a time count stop instruction; a digital type 
indicator for selectively displaying a minute/hour data or a date data 
corresponding to the time count data of the time counting circuit and a 
minute/hour data or a second or less data corresponding to the time 
interval of the time interval counting circuit; first and second switches 
for causing desired functions to be selectively displayed on the 
indicator; and a control circuit in which a normal minute/hour data is 
switched upon closure of the first switch to a date data corresponding to 
the output of the calendar date counter for display on the indicator, the 
minute/hour data or date data is switched to a time interval data based on 
a time count start instruction and time count stop instruction issued upon 
the repetative operation of the second switch, and after the display of 
the time interval data a second or less time interval data from the time 
interval counting circuit can be displayed upon the operation of the first 
switch on the indicator. 
The electronic timepiece according to this invention can display a date 
data on the indicator through the control of the two switches and provide 
a great merit when the timepiece is made compact as in the case of a 
wristwatch.

DETAILED DESCRIPTION 
In the drawing a reference clock signal is generated from an oscillator 11. 
The reference clock signal is properly frequency divided at a frequency 
divider 12 to produce, for example, a one pulse 0.1 second (1P/0.1S) clock 
signal. The clock signal of the frequency divider 12 is supplied as a 
count step signal to a second counting circuit 13 comprised of, for 
example, scale of 10 and scale of 60 counters. The second counting circuit 
13 produces a one pulse per second (1P/1M) output signal. The 1P/1M signal 
of the second counter 13 is supplied as a count step signal to a time 
counting circuit 14 comprised of a scale of 60 and scale of 12 counters 
etc. The time counting circuit 14 provides a minute and hour indication. 
For example, a one pulse per 24 hours (1P/24H) carry signal is generated 
from the time counting circuit 14. The carry signal of the time counting 
circuit 14 is fed to a date counting circuit 15 from which is generated, 
for example, a count signal representative of "a month", "a date" and "a 
day of the week". 
The count signals of the counting circuits 14 and 15 are supplied to AND 
circuits 16 and 17 and the output signals of the AND circuits 16 and 17 
are supplied, as a display signal, through an OR circuit 18 to a digital 
type indicator 19 having a display section indicating a time unit of "an 
hour" and "a minute". 
The 1P/0.1S signal of the frequency divider circuit 12 is coupled as a 
count step signal through an AND circuit 20 to a smaller time unit 
counting circuit 22 which constitutes a time count circuit for performing 
the function of a stopwatch. A carry signal from the counting circuit 22 
is coupled as a count step signal to a greater time unit counting circuit 
23. The counting circuits 22 and 23 are constructed in the same way as the 
second counting circuit 13 and time counting circuit 14. That is, the 
counting circuit 22 is adapted to count the time in smaller time units of 
0.1 to 60 seconds while the gate of the AND circuit 20 is opened and the 
counting circuit 23 is adapted to count the time in greater time units of 
minutes and hours. The count signals of the counting circuits 22 and 23 
are supplied to AND circuits 24 and 25, respectively, and the outputs of 
the AND circuits 24 and 25 are coupled through the OR circuit 18 to the 
indicator 19 so as to function as a stopwatch. 
An electronic timepiece includes a first switch KA of auto-return type 
which is opened during a normal time counting period and closed to select 
a specific function, and a second switch KB for a stopwatch. These 
switches generate a +V signal upon closure. A signal generated upon the 
closure of the first switch KA is coupled to the AND circuits 17 and 24 
and to AND circuits 26 and 27 and inverter 28. When the switch KA is 
opened, the inverter 28 produces an output signal. The output of the 
inverter 28 is coupled as a gate signal to AND circuits 25 and 29. The 
outputs of the AND gates 27 and 29 are coupled to an OR 30 and the output 
of the OR circuit 30 is supplied as a gate signal to the AND circuit 16. 
A signal generated upon the closure of the second switch KB is supplied as 
an inversion trigger signal to a binary flip-flop 31 adapted to invert the 
above-mentioned signal for each operation of the switch KB. The 
above-mentioned signal is also connected to the AND circuit 26. The AND 
circuit 26 is adapted to generate an output signal upon the simultaneous 
operation of the switches KA and KB and the output of the AND circuit 26 
is supplied as a reset instruction to the time counting circuit 21 and to 
an RS flip-flop 32. The binary flip-flop 32 is set when the binary 
flip-flop 31 produces an output "1". The output "1" of the binary 
flip-flop 31 is supplied as a gate signal to the AND circuit 20. The set 
output of the flip-flop 32 is applied as a gate signal to the AND circuit 
25. The output of the binary flip-flop 31 is also coupled through an 
inverter 33 to one gate of the AND circuit 35, and the output of the 
binary flip-flop 31 and the set output of the flip-flop 32 are coupled to 
an AND circuit 34. The set output of the flip-flop 32 is also coupled to 
the AND circuit 35. The output of the AND circuit 34 is connected to the 
AND circuit 27 and the output of the AND circuit 35 is connected to the 
AND circuit 24. The reset output of the flip-flop circuit 32 is connected 
to the AND circuits 29 and 27. 
When the electronic timepiece functions as a normal timepiece, not as a 
stopwatch, the binary flip-flop 31, flip-flop 32 and time counting circuit 
21 are all in the reset state, the second counting circuit 13 is counting 
the time in units of a second and the time counting circuit 14 is counting 
the time as units of minutes and hours. In this state, the flip-flop 32 is 
in the reset state and an output signal of the AND circuit 29 is supplied 
through the OR circuit 30 to the AND circuit 16. In consequence, a time 
count signal of the time counting circuit is supplied to the indicator 19 
where the time is being displayed. 
When the date is to be displayed on the same indicator 19, the first switch 
KA is closed. Since the inverter 28 produces an output "0", the gate of 
the AND circuit 29 is closed and the gate of the AND circuit 16, to which 
the minute/hour count signal is coupled, is closed, interrupting a time 
display on the indicator 19. At the same time, the gate of the AND circuit 
17 is opened and a time count signal of the date counting circuit 15 is 
coupled to the indicator 19, thus effecting a date display on the 
indicator 19. That is, the time and date are selectively displayed on the 
indicator 19 in response to the closure of the first switch KA and the 
timepiece is used as a normal timepiece having a date display. 
Where the timepiece is to be used as a stopwatch, the second switch KB is 
closed with the first switch KA in the open state. The binary flip-flop 31 
is set to cause the gate of the AND circuit 20 to be opened. A clock 
signal of the frequency divider 12 is delivered to the time count circuit 
21. That is, upon the closure of the second switch KB the timepiece starts 
to function as a stopwatch. At the same time the set output of the 
flip-flop 31 causes the flip-flop 32 to be set, supplying a gate signal to 
the AND circuit 25. Since at this time the output of the inverter 28 is 
"1" with the first switch KA in the open state, the gate of the AND gate 
25 is opened, a time count signal of the greater time unit counting 
circuit is coupled to the indicator 19, effecting a minute/hour time 
display. When in this state the second switch KB is again operated, the 
output of the binary flip-flop 31 is reversed. That is, the binary 
flip-flop 31 produces an output "0". The gate of the AND circuit 20 is 
closed, thus stopping the time counting operation of the time counting 
circuit 21. That is, the timepiece functions as a stopwatch and a 
start/stop operation is so repeated. Since at this time the flip-flop 32 
is being set by the initial operation of the second switch KB, the count 
value of the minute/hour time counting circuit 23 in the start/stop time 
counting circuit 21 is displayed on the indicator 19. 
While the timepiece is working as a stopwatch, if a long time interval is 
involved, there arises the necessity of reading an actual time during the 
time counting period. Since the time is read with the binary flip-flop 31 
in the set state and the gate of the AND circuit 20 in the open state, the 
user closes the first switch KA. Since at this time the flip-flop circuit 
32 is set, the set output of the flip-flop circuit 32 is coupled as a gate 
signal to the AND circuit 27 through the AND circuit 34. Upon the closure 
of the first switch KA the AND circuit 27 generates an output signal to 
cause the gate of the AND circuit 16 to be opened. Since the inverter 28 
produces an output "0", the gate of the AND circuit 25 is closed, a time 
count signal of the minute/hour counting circuit 14 is coupled to the 
indicator 19 for time display, while the time counting circuit 21 
continues its time counting operation. That is, upon the closure of the 
first key KA a time display can be effected on the indicator 19 without 
interrupting the stopwatch function. In this case, the time display is 
effected in time units of minutes and hours. However, there arises the 
necessity of effecting a time display in a smaller time unit of a second 
and 0.1 second. Where a smaller time unit is to be displayed on the 
indicator 19, the first switch KA is closed under the condition that the 
above-mentioned time counting is completed and the result of counting is 
held in the time counting circuit 21. That is, the first key switch KA is 
closed when the flip-flop 31 is in the reset state and the flip-flop 
circuit 32 is in the set state. In this state, the inverter 33 produces an 
output "1" and the AND gate 35 generates an output. Simultaneously with 
the closure of the first key switch KA the gate of the AND circuit 25 is 
closed and the gate of the AND circuit 24 is opened. That is, a signal of 
the smaller time unit counting signal is coupled to the indicator 19, 
effecting a time display in time units of a second and 0.1 second. 
If in this state the electronic timepiece is to be used as a normal 
timepiece, the first and second switches KA and KB are simultaneously 
operated. Then, the AND circuit 26 produces an output signal, and the 
flip-flop 32 and time count circuit 21 are reset by the output of the AND 
circuit 26. At this time, the output of the binary flip-flop 31 becomes 
zero. 
Although in the above-mentioned embodiment the clock signal counting 
circuit is used for time display and time counting, any counting means 
such as a combination of a memory means and adding means may be employed 
as such. This invention can be modified in a variety of ways without 
departing from the spirit and scope of this invention.