EP 0087908 A1 19830907 - Electro-acoustic calling devices.
Title (en)
Electro-acoustic calling devices.
Title (de)
Elektroakustische Signalgeber.
Title (fr)
Dispositifs d'avertissement électroacoustiques.
Publication
Application
Priority
GB 8205748 A 19820226
Abstract (en)
An electro-acoustic transducer (2) mounted in a housing (5, 6) in which a volume control is provided by an aperture (7) in the front of the housing (5) and a rotatable shutter plate (11) which is mounted on the front of the housing (5) and which has a plurality of smaller apertures (14). The smaller apertures (14) are positioned in such a way that linear movement of the shutter plate (11) causes a logarithmic change in the exposure of the aperture (7) in the front of the housing (5) to give a logarithmic change in the intensity of the sound output such that the linear movement causes an apparent linear change in the intensity of sound as heard by a human ear.
IPC 1-7
IPC 8 full level
H04R 17/10 (2006.01); G10K 11/02 (2006.01); H04M 1/00 (2006.01); H04R 1/22 (2006.01)
CPC (source: EP)
H04R 1/22 (2013.01)
Citation (search report)
- [A] GB 2082018 A 19820224 - STANDARD TELEPHONES CABLES LTD
- [A] FR 2273335 A1 19751226 - KLAXON SA [FR], et al
- [A] US 3826333 A 19740730 - BUCKWALTER J
- [A] US 1884724 A 19321025 - KELLER ARTHUR C
Designated contracting state (EPC)
AT BE CH DE FR IT LI LU NL SE
DOCDB simple family (publication)
EP 0087908 A1 19830907; EP 0087908 B1 19851204; AT E16879 T1 19851215; AU 1149283 A 19830901; AU 549945 B2 19860220; CA 1215163 A 19861209; DE 3361370 D1 19860116; DK 78383 A 19830827; DK 78383 D0 19830222; GB 2115648 A 19830907; GB 2115648 B 19850313; GB 8305038 D0 19830330; HK 79485 A 19851025; IL 67935 A0 19830615; IL 67935 A 19860429; JP S58159099 A 19830921; KE 3554 A 19850830; MY 8600266 A 19861231; NZ 203265 A 19850430; ZA 831054 B 19840328; ZW 5283 A1 19830511
DOCDB simple family (application)
EP 83300910 A 19830222; AT 83300910 T 19830222; AU 1149283 A 19830216; CA 421729 A 19830216; DE 3361370 T 19830222; DK 78383 A 19830222; GB 8305038 A 19830223; HK 79485 A 19851017; IL 6793583 A 19830216; JP 3064283 A 19830225; KE 355485 A 19850807; MY 8600266 A 19861230; NZ 20326583 A 19830214; ZA 831054 A 19830216; ZW 5283 A 19830225