Electrical audio signal processing systems and devices – Electro-acoustic audio transducer – Electrostrictive – magnetostrictive – or piezoelectric
Patent
1992-01-24
1994-06-14
Kuntz, Curtis
Electrical audio signal processing systems and devices
Electro-acoustic audio transducer
Electrostrictive, magnetostrictive, or piezoelectric
381173, 381114, 310317, H04R 2500
Patent
active
053217616
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The present invention relates to a piezoelectric sound generator and a method of its manufacture. More specifically, it relates to a piezoelectric sound generator for utilization in a telephone receiver incorporating a leakage magnetic flux coil for hearing aid users.
2. Background Art
Japanese Patent Laying-Open No. 102496/1988 and Japanese Patent Laying-Open No. 102497/1988 disclose piezoelectric sound generators provided in telephone receivers for people using hearing aids. The generators have a coil wound around a case containing a piezoelectric device. The coil generates a leakage magnetic flux when supplied with an electric current. The leakage magnetic flux then induces the pickup coil in a user's hearing aid to generate current.
The piezoelectric device of the conventional piezoelectric sound generator is enclosed in a case which is contained in a telephone receiver, and the coil is disposed inward of the piezoelectric device, or toward the side nearer a user's ear. The piezoelectric device and the coil are connected in parallel in order to bring about both acoustic pressure characteristics and leakage magnetic flux characteristics which are satisfactory. Additionally, a single resistor is provided exterior of the generator, connected in series to a terminal of the piezoelectric device. The resistor serves to regulate the acoustic pressure level of the piezoelectric device and to maintain the leakage magnetic flux at sufficient strength.
However, the sound waves reproduced by a piezoelectric device of the foregoing structure tend to be deformed, due to an imbalance in the impedance between the two terminals of the device. Moreover, very high voltages generated in the piezoelectric device by static electricity or by strong external mechanical forces may deteriorate the IC's of an associated driver circuit.
The piezoelectric device of the conventional piezoelectric sound generator comprises a metal diaphragm, a piezoelectric porcelain affixed to the metal diaphragm, and a pair of anterior and posterior metal cases containing the piezoelectric device so as to form anterior and posterior cavities.
A plurality of sound-emission holes are formed in the anterior metal case, and formed in the posterior metal case is an acoustic-pressure relief hole over which a mesh sheet providing acoustic resistance is affixed. The pair of metal cases containing the piezoelectric device are installed in the handset of a telephone. An auxiliary cavity is formed between a the handset having sound-emission holes and the anterior metal case.
The sound waves emitted from the piezoelectric device of this sound generator travel to the ear of a user through the anterior cavity formed between the piezoelectric device and the anterior metal case, and the auxiliary cavity formed between the anterior metal case and the handset wall. Accordingly, the dimensional volume of these cavities affects the acoustic characteristics therein.
Handsets of reduced size and thickness have been developed for portable telephones which have come into widespread use. However, in a handset employing the conventional piezoelectric sound generator, the auxiliary cavity formed between the metal cases and the handset in addition to the pair of cavities formed within the metal cases imposes an unsuitable limitation on the extent to which its thickness can be reduced.
Since it is highly desirable that the parts built in a receiver be reduced in size, a piezoelectric buzzer has been disclosed in Japanese Patent Laying-Open No. 96799/1990 wherein its terminals are integrally set into a resin case containing the piezoelectric device, for application in a telephone set.
However, electronic components must be soldered to the terminals of this structure, which soldering raises the temperature of the terminals to approximately 200.degree. C. to 300.degree. C., and which in turn may deform the portions of the resin case into which the terminals are contained. Should the resin material become deformed, the connection between the piezoe
REFERENCES:
patent: 4157459 (1979-06-01), Bush et al.
patent: 4295099 (1981-10-01), Weidler
patent: 4596899 (1986-06-01), Wojcik et al.
Kuntz Curtis
Kyocera Corporation
Le Huyen D.
LandOfFree
Piezoelectric sound generator and method of its manufacture does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Piezoelectric sound generator and method of its manufacture, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Piezoelectric sound generator and method of its manufacture will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1255321