Communications: electrical – Audible indication
Reexamination Certificate
2000-01-20
2003-01-28
Lieu, Julie (Department: 2632)
Communications: electrical
Audible indication
C340S384600, C381S339000, CD10S120000
Reexamination Certificate
active
06512450
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an improved noise-making device used to provide audible alarms in a wide variety of devices including, for example, automobiles and trucks, industrial equipment, medical devices, traffic signals, appliances and the like. Such devices can use a piezoelectric transducer and associated circuitry to produce sound at a given frequency. The transducer flexes in response to an applied voltage. If an oscillating voltage is applied to the transducer at an appropriate rate, the flexing of the transducer produces an audible sound of substantial volume. Prior devices produce an audible sound at 3 KHz.
In the invention, the sound produced is not 3 KHz. Instead, the sound produced is at a lower frequency, 2 KHz, that is more easily heard and distinguished, especially in a noisy environment. A sound at 2 KHz is also more likely to be perceived by more persons than is a sound at 3 KHz, due to the loss of hearing as the normal person ages. In another feature of the invention, multiple sound cavities amplify in stages the sound produced by the transducer, making it considerably louder and easier to hear.
U.S. Pat. No. 5,990,784 “Schmitt Trigger Loud Alarm With Feedback,” is incorporated by reference herein and describes an alarm device using a piezoelectric transducer. This patent is owned by the assignee of the present invention.
SUMMARY OF THE INVENTION
According to the invention, there is provided a piezoelectric transducer and associated electrical circuitry to cause the transducer to oscillate at a resonant audible frequency. The transducer is mounted to a proximal tubular housing which is hollow, thus providing a first cavity. A second or distal tubular housing forms a second cavity adjoining the first cavity, and is of larger diameter than the first cavity. A third cavity adjoining the second cavity may optionally be employed. Sound is produced by the transducer and passes through the first cavity, second cavity and, if used, the third cavity. The sound is through a grill on the last cavity. The invention provides an audible sound at 2 KHz by means of an amplifier circuit including feedback from the transducer to the amplifier. The transducer resonates, producing an audible sound at 2 KHz. The cavities cause the sound to be greatly amplified when compared to similar devices not using multiple cavities.
REFERENCES:
patent: 1590814 (1926-06-01), Durett
patent: 3815129 (1974-06-01), Sweany
patent: 4213121 (1980-07-01), Learn et al.
patent: 4429247 (1984-01-01), Feldman
patent: 5406637 (1995-04-01), Gonzalez
patent: 5675312 (1997-10-01), Burnett
patent: 5872506 (1999-02-01), O'Brien et al.
patent: 5990784 (1999-11-01), Burnett
Mallory, SONALERT electric audible signals: It's uses are limited only by your imagination (product catalog).
Baldwin Christopher Michael
Burnett George Alan
Lieu Julie
Mallory Sonalert Products, Inc.
Niro Scavone Haller & Niro
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