Thin type speaker having a secondary diaphragm

Details Thin type speaker having a secondary diaphragm Thin type speaker having a secondary diaphragm

1998-10-20

2001-04-10

Le, Huyen (Department: 2743)

Electrical audio signal processing systems and devices

Electro-acoustic audio transducer

Electromagnetic

C381S423000, C181S148000

Reexamination Certificate

active

06215887

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thin type speaker, and more specifically to a speaker having a diaphragm of which the surface is covered with a secondary diaphragm. The secondary diaphragm can enhance the power capacity of the speaker and gives the speaker a larger flat effective bandwidth, with less noise. The speaker can be produced at low cost.
2. Description of the Prior Art
A conventional thin type speaker, as shown in
FIGS. 1 and 2
, is used in earphones, notebook computers, or miniature type radios and cassette recorders. The prior art speaker is generally composed of an enclosure
10
, a mylar cone diaphragm
20
, a yoke
30
, a sound coil
40
, a magnet
50
, a washer
60
and a tab
70
. The yoke
30
and the enclosure
10
can be integrated into a single piece. The diaphragm
20
is made of plastic material. Such a structure and materials were not changed in the past. After a wide application in the field, it becomes evident that the power capacity of the thin type speaker is rather small (around 0.3 watt). The vibration of the diaphragm
20
often produced noises and the fo value is high while the low frequency effect is poor. Also, the effective bandwidth is small (approximately between 1200 Hz and 10000 Hz). The dB value is around 83.4 dB at 1.26 volts (refer to
FIG. 3
for details). Thus the actual sounding effect is not satisfied.
SUMMARY OF THE INVENTION
The primary object of the invention is to provide a thin type speaker having a secondary diaphragm which speaker consists of an enclosure, a mylar cone vibration diaphragm, a yoke, a sound coil, a magnet, and a washer. The vibration diaphragm is further provided with a secondary diaphragm on the surface thereof. The secondary diaphragm is made of sponge, cloth, paper, cardboard, or isolating fabric. With such a structure, the speaker can have larger tensioning at a higher power output and thus enhance the power capacity. It has been proven by tests that the power capacity of such a speaker can reach 1.5 volts. Also, the inventive speaker has larger flat effective bandwidth, which is approximately between 400 Hz and 20000 Hz, with less noise, and low costs in manufacturing.


REFERENCES:
patent: 2974204 (1961-03-01), Supitilov
patent: 4315112 (1982-02-01), Hofer
patent: 4478309 (1984-10-01), Kawamura et al.
patent: 5588066 (1996-12-01), Yang et al.
patent: 5627904 (1997-05-01), Yang et al.

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