|
An alarm clock is a clock that is designed to make a sound, or some other signal, at a specific time. The primary utility of these clocks is to awaken people from their night's sleep or short naps; they are sometimes used for other reminders as well. Most use sound; some use light or vibration. Some have sensors to identify when a person is in a light stage of sleep, in order to avoid waking someone who is deeply asleep, which causes tiredness, even if the person has had adequate sleep. To stop the sound or light, a button or handle on the clock is pressed; most clocks automatically stop the alarm if left unattended long enough. A classic analog alarm clock has an extra hand or inset dial that is used to specify the time at which to activate the alarm. Alarm clocks are also found on mobile phones and watches. Traditional mechanical alarm clocks have one or two bells that ring by means of a mainspring that powers a gear to propel a hammer back and forth between the two bells or between the interior sides of a single bell. In some models, the back encasement of the clock itself acts as the bell. In an electric bell-style alarm clock, the bell is rung by an electromagnetic circuit and armature that turns the circuit on and off repeatedly. Digital alarm clocks can make other noises. Simple battery-powered alarm clocks make a loud buzzing or beeping sound to wake a sleeper, while novelty alarm clocks can speak, laugh, sing, or play sounds from nature. Some alarm clocks have radios that can be set to start playing at specified times, and are known as ''clock radios''. Some alarm clocks can set multiple alarms, a useful feature for couples who have different waking up schedules. A ''progressive alarm clock'', still new in the market, can have different alarms for different times (see Next-Generation Alarms). Most modern televisions, mobile phones and digital watches have alarm clock functions to turn on or make sounds at a specific time. == History == The ancient Greek philosopher Plato (428–348 BC) was said to possess a large water clock with an unspecified alarm signal similar to the sound of a water organ; he used it at night, possibly for signaling the beginning of his lectures at dawn (Athenaeus 4.174c).〔; 〕 The Hellenistic engineer and inventor Ctesibius (fl. 285–222 BC) fitted his clepsydras with dial and pointer for indicating the time, and added elaborate "alarm systems, which could be made to drop pebbles on a gong, or blow trumpets (by forcing bell-jars down into water and taking the compressed air through a beating reed) at pre-set times" (Vitruv 11.11). The late Roman senator Cassiodorus (c. 485–585) advocated in his rulebook for monastic life the water clock as a useful alarm for the 'soldiers of Christ' (Cassiod. Inst. 30.4 f.).〔 The Christian rhetorician Procopius described in detail prior to 529 a complex public striking clock in his home town Gaza which featured an hourly gong and figures moving mechanically day and night.〔Dohrn-van Rossum, Gerhard, "Clocks", Brill's New Pauly, edited by: Hubert Cancik and Helmuth Schneider, 2009〕 In China, a striking clock was devised by the Buddhist monk and inventor Yi Xing (683–727).〔Joseph Needham, Volume 4, Part 2, pp. 473–5〕 The Chinese engineers Zhang Sixun and Su Song integrated striking clock mechanisms in astronomical clocks in the 10th and 11th centuries, respectively.〔Joseph Needham, Volume 4, Part 2, p. 165〕 A striking clock outside of China was the water-powered clock tower near the Umayyad Mosque in Damascus, Syria, which struck once every hour. It was constructed by the Arab engineer al-Kaysarani in 1154. In 1235, an early monumental water-powered alarm clock that "announced the appointed hours of prayer and the time both by day and by night" was completed in the entrance hall of the Mustansiriya Madrasah in Baghdad. From the 14th century, some clock towers in Western Europe were also capable of chiming at a fixed time every day; the earliest of these was described by the Florentine writer Dante Alighieri in 1319.〔Joseph Needham, Volume 4, Part 2, p. 445〕 The most famous original striking clock tower still standing is possibly the one in St Mark's Clocktower in St Mark's Square, Venice. The St Mark's Clock was assembled in 1493, by the famous clockmaker Gian Carlo Rainieri from Reggio Emilia, where his father Gian Paolo Rainieri had already constructed another famous device in 1481. In 1497, Simone Campanato moulded the great bell (h. 1,56 m., diameter m. 1,27), which was put on the top of the tower where it was alternatively beaten by the ''Due Mori'' (''Two Moors''), two bronze statues (h. 2,60) handling a hammer. User-settable mechanical alarm clocks date back at least to 15th-century Europe. These early alarm clocks had a ring of holes in the clock dial and were set by placing a pin in the appropriate hole.〔p. 249, ''The Grove encyclopedia of decorative arts'', Gordon Campbell, vol. 1, Oxford University Press, 2006, ISBN 0-19-518948-5.〕〔("Monastic Alarm Clocks, Italian" ), entry, Clock Dictionary.〕 Another mechanical alarm clock was created by Levi Hutchins, of New Hampshire in the United States, in 1787. This device he made only for himself however, and it only rang at 4 AM, in order to wake him for his job.〔(【引用サイトリンク】 History of Clocks )〕 The French inventor Antoine Redier was the first to patent an adjustable mechanical alarm clock, in 1847. Alarm clocks, like almost all other consumer goods in the United States, ceased production in the spring of 1942, as the factories which made them were converted over to war work during World War II, but they were one of the first consumer items to resume manufacture for civilian use, in November 1944. By that time, a critical shortage of alarm clocks had developed due to older clocks wearing out or breaking down. Workers were late for, or missed completely, their scheduled shifts in jobs critical to the war effort. In a pooling arrangement overseen by the Office of Price Administration, several clock companies were allowed to start producing new clocks, some of which were continuations of pre-war designs, and some of which were new designs, thus becoming among the first "postwar" consumer goods to be made, before the war had even ended. The price of these "emergency" clocks was, however, still strictly regulated by the Office of Price Administration. The first radio alarm clock was invented by James F. Reynolds, in the 1940s and another design was also invented by Paul L. Schroth Sr. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「alarm clock」の詳細全文を読む スポンサード リンク
|