Electronic watch
AssigneeEbauches S.A.
InventorFridolin Wiget
Life of this patent
Estimating the term…
Abstract
In an electronic watch, the content of the memory associated with the adjusting circuit of the division ratio of the frequency divider is modified at each correction of the display to compensate for the frequency error of the crystal oscillator and to thereby reduce the running error of the watch. Such electronic watches use a crystal oscillator whose frequency is not optimum. To compensate for the frequency variations due to manufacturing tolerances, age and temperature, correction circuits are incorporated into such watches. When an operator acts on a switch on the case of the watch to correct the time display indication, the content of the memory is modified to correct for the frequency error of the crystal oscillator.
Claims3
An electronic watch comprising
- a quartz oscillator;
- a frequency divider having an adjustable division ratio, connected to receive electrical pulses from said oscillator and produce time standard pulses;
- an adjusting circuit connected to said frequency divider for adjusting said division ratio;
- a memory circuit connected to said adjusting circuit for storing information relating to the value of said division ratio, said memory circuit including a reversible binary counter having a first and a second input for respectively incrementing and decrementing said information;
- time counting circuit having time information outputs and including a seconds counter connected to receive time standard pulses from said frequency divider;
- a display circuit for displaying time information, connected to receive time information signals from said time counting circuit;
- a first logic circuit connected to said seconds counter and having an output which takes a first state when the content of said seconds counter is from 0 to 29 and a second state when the content of said seconds counter is from 30 to 59;
- a correction circuit for setting said time counting circuit to a predetermined time information state;
- means for controlling said correction circuit;
- and
- a second logic circuit having a first input connected to said controlling means, a second input connected to the output of said first logic circuit, a first and a second output connected respectively to the first and second input of said reversible binary counter, said first and second outputs being respectively enabled by the first and second state of the output of said first logic circuit, and said enabled output being activated by an action on said controlling means,
- whereby an action on said controlling means sets said time counting circuit to a predetermined time information state and increments or decrements said division ratio information by one unity step in a direction corresponding to the correction of the period of said time standard pulses.
Dependencies are inferred from the claim text.