วันพฤหัสบดีที่ 24 เมษายน พ.ศ. 2551

Digital clocks


Digital clocks

Digital clock outside Kanazawa Station displaying the time by controlling valves on a fountain
Digital clocks display a numeric representation of time. Two numeric display formats are commonly used on
digital clocks:
the
24-hour notation with hours ranging 00–23;
the
12-hour notation with AM/PM indicator, with hours indicated as 12AM, followed by 1AM–11AM, followed by 12PM, followed by 1PM–11PM (a notation mostly used in the United States).
Most digital clocks use an
LCD, LED, or VFD display; many other display technologies are used as well (cathode ray tubes, nixie tubes, etc.). After a reset, battery change or power failure, digital clocks without a backup battery or capacitor either start counting from 00:00, or stay at 00:00, often with blinking digits indicating that time needs to be set. Some newer clocks will actually reset themselves based on radio or Internet time servers that are tuned to national atomic clocks. Since the release of digital clocks in the mainstream, the use of analogue clocks has dropped dramatically.

ไม่มีความคิดเห็น: