JPS577581A - Time generating device - Google Patents

Abstract

PURPOSE:To prevent reading of erroneous time information by arranging such that, when there is no change from a valid display value to an invalid display value within a predetermined period, an error is recognized and invalid display value is maintained until a next change takes place. CONSTITUTION:A checking circuit 11 is adapted to continuously check for abnormality of time information delivered by a clock circuit 10 through a timinginformation line 100. When any abnormality is found, the checking circuit 11 informs of the abnormality in the clock circuit 10 by means of a time information error signal transmitted to a gate circuit 30 through a signal line 110. Another checking circuit 21 continuously checks for any abnormality of valid display signal which is delivered thereto by a generating circuit 20 through a signal line 200. When any abnormality is found, the checking circuit 21 delivers a signal through a signal line 210 to the circuit 30 to inform the latter of the abnormality in the circuit 20. The effective display signal to the time receiving device 2 is forcibly maintained as an invalid display value till the next change, when abnormality of time information is detected by the circuit 11 or when abnormality in the effective display signal is detected by the circuit 21.