Open main menu
Home
Random
Recent changes
Special pages
Community portal
Preferences
About Wikipedia
Disclaimers
Incubator escapee wiki
Search
User menu
Talk
Dark mode
Contributions
Create account
Log in
Editing
Clock
(section)
Warning:
You are not logged in. Your IP address will be publicly visible if you make any edits. If you
log in
or
create an account
, your edits will be attributed to your username, along with other benefits.
Anti-spam check. Do
not
fill this in!
==Types== Clocks can be classified by the type of time display, as well as by the method of timekeeping. ===Time display methods=== ====Analog==== {{See also|Clock face}} [[File:Rew17h09 1977.jpg|thumb|A modern quartz clock with a 24-hour face]] [[File:Picadillycircuslinearclock.jpg|thumb|right|A linear clock at London's [[Piccadilly Circus tube station]]. The 24 hour band moves across the static map, keeping pace with the apparent movement of the sun above ground, and a pointer fixed on London points to the current time.]] Analog clocks usually use a [[clock face]] which indicates time using rotating pointers called "hands" on a fixed numbered dial or dials. The standard clock face, known universally throughout the world, has a short "hour hand" which indicates the hour on a circular dial of 12 [[hour]]s, making two revolutions per day, and a longer "minute hand" which indicates the minutes in the current hour on the same dial, which is also divided into 60 minutes. It may also have a "second hand" which indicates the seconds in the current minute. The only other widely used clock face today is the [[24 hour analog dial]], because of the use of [[24 hour time]] in military organizations and timetables. Before the modern clock face was standardized during the [[Industrial Revolution]], many other face designs were used throughout the years, including dials divided into 6, 8, 10, and 24 hours. During the [[French Revolution]] the French government tried to introduce a [[10-hour clock]], as part of their decimal-based [[metric system]] of measurement, but it did not achieve widespread use. An Italian 6 hour clock was developed in the 18th century, presumably to save power (a clock or watch striking 24 times uses more power). Another type of analog clock is the sundial, which tracks the sun continuously, registering the time by the shadow position of its [[gnomon]]. Because the sun does not adjust to daylight saving time, users must add an hour during that time. Corrections must also be made for the [[equation of time]], and for the difference between the longitudes of the sundial and of the central meridian of the [[time zone]] that is being used (i.e. 15 degrees east of the [[prime meridian]] for each hour that the time zone is ahead of [[GMT]]). Sundials use some or part of the 24 hour analog dial. There also exist clocks which use a digital display despite having an analog mechanism—these are commonly referred to as [[flip clock]]s. Alternative systems have been proposed. For example, the "Twelv" clock <!-- not a typo, see http://www.gizmag.com/go/6312/ -->indicates the current hour using one of twelve colors, and indicates the minute by showing a proportion of a circular disk, similar to a [[Lunar phase|moon phase]].<ref>{{US Patent|7079452}}, {{US Patent|7221624}}</ref> ====Digital==== {{Main|Digital clock}} <gallery mode="packed-hover" heights="150px" caption="Examples of digital clocks"> Kanazawa Station Water Clock.jpg|Digital clock<!-- outside [[Kanazawa Station]]--> displaying time by controlling valves on the fountain Digital-clock-radio-basic hf.jpg|Simplistic digital clock radio Analog clock with digital display.png|Diagram of a mechanical digital display of a [[flip clock]] Cifra 5 digital flip clock designed by Gino Valle (1957).jpg|Cifra 5 digital flip clock (1957) SAMSUNG Galaxy S22 Ultra BLACK.jpg|A digital clock on a [[Samsung Galaxy]] smartphone </gallery> Digital clocks display a numeric representation of time. Two numeric display formats are commonly used on [[Digital data|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 domestic environments). Most digital clocks use electronic mechanisms and [[LCD]], [[LED]], or [[vacuum fluorescent display|VFD]] displays; many other display technologies are used as well ([[cathode-ray tube]]s, [[nixie tube]]s, etc.). After a reset, battery change or power failure, these clocks without a backup battery or [[capacitor]] either start counting from 12:00, or stay at 12:00, often with blinking digits indicating that the time needs to be set. Some newer clocks will reset themselves based on radio or Internet [[time server]]s that are tuned to national [[atomic clock]]s. Since the introduction of digital clocks in the 1960s, there has been a notable decline in the use of analog clocks.<ref>{{cite book |last1=Sadraey |first1=Mohammad H. |title=Design of Unmanned Aerial Systems |date=2020 |publisher=John Wiley & Sons |isbn=978-1-119-50870-0 |page=332}}</ref> Some clocks, called '[[flip clock]]s', have digital displays that work mechanically. The digits are painted on sheets of material which are mounted like the pages of a book. Once a minute, a page is turned over to reveal the next digit. These displays are usually easier to read in brightly lit conditions than LCDs or LEDs. Also, they do not go back to 12:00 after a power interruption. Flip clocks generally do not have electronic mechanisms. Usually, they are driven by [[Alternating current|AC]]-[[synchronous motor]]s. ====Hybrid (analog-digital)==== Clocks with analog quadrants, with a digital component, usually minutes and hours displayed analogously and seconds displayed in digital mode. ====Auditory==== {{Main|Talking clock}} For convenience, distance, telephony or blindness, auditory clocks present the time as sounds. The sound is either spoken natural language, (e.g. "The time is twelve thirty-five"), or as auditory codes (e.g. number of sequential bell rings on the hour represents the number of the hour like the bell, [[Big Ben]]). Most telecommunication companies also provide a [[speaking clock]] service as well. ====Word==== [[File:Word clock wallpaper with comic speech bubble style.png|thumb|Software word clock]] Word clocks are clocks that display the time visually using sentences. E.g.: "It's about three o'clock." These clocks can be implemented in hardware or software. ====Projection==== {{Main|Projection clock}} Some clocks, usually digital ones, include an optical [[Image projector|projector]] that shines a magnified image of the time display onto a screen or onto a surface such as an indoor ceiling or wall. The digits are large enough to be easily read, without using glasses, by persons with moderately imperfect vision, so the clocks are convenient for use in their bedrooms. Usually, the timekeeping circuitry has a battery as a backup source for an uninterrupted power supply to keep the clock on time, while the projection light only works when the unit is connected to an A.C. supply. Completely battery-powered portable versions resembling [[flashlight]]s are also available. ====Tactile==== Auditory and projection clocks can be used by people who are blind or have limited vision. There are also clocks for the blind that have displays that can be read by using the sense of touch. Some of these are similar to normal analog displays, but are constructed so the hands can be felt without damaging them. Another type is essentially digital, and uses devices that use a code such as [[Braille]] to show the digits so that they can be felt with the fingertips. ====Multi-display==== Some clocks have several displays driven by a single mechanism, and some others have several completely separate mechanisms in a single case. Clocks in public places often have several faces visible from different directions, so that the clock can be read from anywhere in the vicinity; all the faces show the same time. Other clocks show the current time in several time-zones. Watches that are intended to be carried by travellers often have two displays, one for the local time and the other for the time at home, which is useful for making pre-arranged phone calls. Some [[equation clock]]s have two displays, one showing [[Local mean time|mean time]] and the other [[Solar time#Apparent solar time|solar time]], as would be shown by a sundial. Some clocks have both analog and digital displays. Clocks with Braille displays usually also have conventional digits so they can be read by sighted people.
Edit summary
(Briefly describe your changes)
By publishing changes, you agree to the
Terms of Use
, and you irrevocably agree to release your contribution under the
CC BY-SA 4.0 License
and the
GFDL
. You agree that a hyperlink or URL is sufficient attribution under the Creative Commons license.
Cancel
Editing help
(opens in new window)