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The diaphone is a noisemaking device best known for its use as a foghorn: It can produce deep, powerful tones, able to carry a long distance. Although they have fallen out of favor, diaphones were also used at some fire stations and in other situations where a loud, audible signal was required. ==History== The diaphone horn was based directly on the organ stop of the same name invented by Robert Hope-Jones, creator of the Wurlitzer organ.〔Michael Lamm (Winter 2003) "Feel the Noise: The art and science of making sound alarming," ''Invention & Technology'', 18 (3) : 22-27.〕〔(Seeing the Light: "The diaphone fog signal" by Jeff Laser )〕 Hope-Jones' design was based on a piston that was closed only at its bottom end and had slots, perpendicular to its axis, cut through its sides; the slotted piston moved within a similarly slotted cylinder. Outside of the cylinder was a reservoir of high-pressure air. Initially, high-pressure air would be admitted behind the piston, pushing it forward. When the slots of the piston aligned with those of the cylinder, air passed into the piston, making a sound and pushing the piston back to its starting position, whence the cycle would repeat.〔For the patents of Hope-Jones' diaphones that were used as foghorns, see: * Hope-Jones, R., "Sound-producing apparatus suitable for sirens, organs, etc.," British patent 26,738 (31 Dec. 1901). See: ''Patents for Inventions: Abridgements of Specifications … Period -- A.D. 1901-4.'' (London, England: Patent Office, 1907) (page 122 ). * Robert Hope-Jones, ("Sound-producing device suitable for sirens, etc.," ) U.S. patent 702,557 (filed: 26 Nov. 1901; issued 17 June 1902).〕 A modification of Hope-Jones' design was patented by John Pell Northey, head of the Northey Co. Ltd. of Toronto, Ontario, Canada, which manufactured pumps and small gasoline engines.〔For further information about John Pell Northey and the Northey Company of Toronto, see: * (SmokStak: The Northey Co., Ltd. ) * (Buzzcoil.Brinkster.net/Northey ).〕 Northey added a secondary compressed air supply to the piston in order to power it during both its forward and reverse strokes and thus create an even more powerful sound.〔Northey's patents for diaphones: * John Pell Northey, ("Sound-producing device suitable for sirens or like instruments," ) U.S. Patent 736,428 (filed: 22 Nov. 1902 ; issued: 18 Aug. 1903). This patent mentions a second source of high-pressure air that caused the slotted piston to reciprocate. * John Pell Northey, ("Sound-producing device," ) U.S. Patent 973,960 (filed: 5 June 1908 ; issued: 25 Oct. 1910). * John Pell Northey, ("Sound-producing device," ) U.S. patent 976,682 (filed: 5 June 1908 ; issued: 22 Nov. 1910). * John Pell Northey, ("Sound-signaling installation," ) U.S. Patent 1,619,585 (filed: 8 June 1926 ; issued: 1 March 1927). * John P. Northey, ("Sound-producing device," ) U.S. patent 1,799,387 (filed: 1 March 1929 ; issued: 7 April 1931).〕 The entire horn apparatus was driven by a compressor. To manufacture the new equipment, Northey set up the Diaphone Signal Co. at Toronto in 1903.〔Laser, J. ''(Seeing the Light )'' accessed 2008-03-09〕 It manufactured a range of diaphone models: the large "Type F", which created a tone of about 250 Hz, found worldwide use as a fog signal, especially in lighthouses. The mechanism of the diaphone created a noticeable low-frequency "grunt" at the end of each note produced, caused by the piston decelerating as the air supply was cut. As this low-frequency sound could carry further, Northey's son Rodney redesigned the "Type F" model to sustain the second low tone,〔Rodney V. Northey, ("Sound-producing device," ) U.S. patent 1,844,226 (filed: 27 March 1931; issued 9 February 1932).〕 creating the familiar (two-tone fog signal ), commonly used in lighthouses and lightvessels in the United States and Canada (as well as in a famous series of radio commercials for Lifebuoy soap). This version, known as the "Improved Type F" or later as the "F2T", was particularly common in installations on the West Coast of the United States and in lightvessels.〔Laser, J. ''(Seeing the Light )'' accessed 2008-03-09〕 Installations in Europe generally used single-tone diaphones.〔Fox, F. (Diaphone at Douglas Head Lighthouse ) accessed 2008-03-09〕 Rodney Northey sold the Diaphone Signal Co. in 1932, when it was bought by a Buffalo, New York company, Deck Brothers, working under contract for the United States Lighthouse Service.〔Laser, J. ''(Seeing the Light )'' accessed 03-09-08. Northey sold the company as he required money to marry his fiancée.〕 This company still exists, although it no longer manufactures diaphones. The European manufacturing rights were obtained by Chance Brothers of Birmingham in the United Kingdom, already a major supplier of Fresnel lenses and other equipment to lighthouse authorities. In use, the diaphone was generally found to be reliable and suffered little from wear, as the lightweight piston floated on a cushion of air during oscillation.〔Renton, A. ''Lost Sounds: the story of coast fog signals'', 2003, p.163〕 Such wear as did occur tended to happen as a result of the piston becoming loose: as the pistons were custom-made〔(Bringing Back the Sound of San Francisco ), ''Christian Science Monitor'', Jul 1983〕 and the design to some degree affected the individual sound characteristics of the signal, the manufacturers supplied two spare pistons with each diaphone.〔Renton, A. ''Lost Sounds: the story of coast fog signals'', 2003, p.163〕 The majority of diaphone installations were removed or became disused during the 1960s and 1970s. This was partly a result of automation of lighthouses, but it was also found that modern diaphragm horns would produce similar levels of volume to a diaphone while requiring much smaller and less powerful compressors.〔American Society of Mechanical Engineers, ''Annual Proceedings of the Diesel and Gas Engine Power Division'', V. 33-34 (1961), p.18〕 By 1983, the last two-tone "F2T" type in full time operation in the United States was at Edgartown, Martha's Vineyard.〔(Bringing Back the Sound of San Francisco ), ''Christian Science Monitor'', Jul 1983〕 A few survive in working condition in lighthouses around the world. 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「diaphone」の詳細全文を読む スポンサード リンク
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