Electrical audio signal processing systems and devices – Electro-acoustic audio transducer – Electromagnetic
Reexamination Certificate
1999-05-27
2001-07-10
Kuntz, Curtis (Department: 2643)
Electrical audio signal processing systems and devices
Electro-acoustic audio transducer
Electromagnetic
C340S384730, C340S388100, C340S391100, C340S398100, C340S384700, C381S398000, C381S412000, C381S419000, C181S000500, C181S179000
Reexamination Certificate
active
06259797
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a component in anti-theft installation. More particularly, the present invention relates to a metal base assembly inside a speaker capable of generating a high tone warning sound.
2. Description of Related Art
Due to the rapid economic development of our society, the material quality of our life continues to improve. Transport vehicles such as cars or motorcycles are often used to convey people to and from work or for leisure travel. In fact, they have become an almost indispensable part in the life of most families.
In general, most new cars or motorcycles are equipped with two anti-theft systems for burglary prevention. In addition to a lock guarding the engine starter, door locks and an anti-theft alarm system are frequently included for added security.
Among the many installations in an anti-theft system, the most important one is a high-tone speaker. The high tone warning sound produced by a speaker is quite effective in scaring off would-be burglars. The high tone sound of a speaker is generated by the rapid vibration of an acoustic diaphragm whose motion is in turn induced by a rapidly changing magnetic field.
The rapidly changing magnetic field is produced by supplying a current and forming a complete magnetic circuit through a metal base.
FIG. 1
is an exploded view of components in a conventional anti-theft speaker together with an unit assembled from these components. A speaker
20
as shown in
FIG. 1
comprises several components, including: a speaker casing
10
, a mounting block
12
, an acoustic diaphragm assembly
14
, a plastic pad
16
and a metal base
18
for forming a magnetic circuit.
The speaker casing
10
has a plurality of guiding pins
22
protruding from the bottom surface. The guiding pins
22
are inserted into holes (not shown) on the mounting block
12
during an assembling process. The mounting block
12
also has a few holes (not shown) reserved for putting screws
30
in so that the acoustic diaphragm assembly
14
, the plastic pad
16
and the metal base
18
can be attached together. The mounting block
12
also has a few slots permitting wires from the acoustic diaphragm assembly
14
and other structural elements to exit.
The acoustic diaphragm assembly
14
couples with the mounting block
12
in such a way that the side with a bulging diaphragm
26
faces the interior of the mounting block
12
. When the diaphragm
26
vibrates, a high tone sound is produced. The other side of the acoustic diaphragm assembly
14
, on the other hand, hides a circular magnetic field generator (not shown). When a proper electrical signal is fed into a magnetic coil inside the generator via wires
28
, a rapidly fluctuating magnetic field is produced. The changing magnetic field in combination with the metal base
18
can induce vibration of the diaphragm
26
.
The plastic pad
16
is a component for stationing the acoustic diaphragm assembly
14
. Inside the metal base
18
, there is a circular recess cavity
34
for accommodating the circular magnetic field generator on the acoustic diaphragm assembly
14
. The metal base
18
has a plurality of holes
32
around the peripheral region for accommodating the screws
30
after it passes through the mounting block
12
.
FIG. 2
is a diagram showing the components of the metal base illustrated in FIG.
1
. The metal base
18
comprises a metal plate
35
, a magnetic plate
36
and a base block
38
. The metal plate
35
and the magnetic plate
36
are both circular and their diameters are the same. The metal base
18
has a circular recess cavity
37
in the middle with an internal diameter slightly larger than the diameters of the metal plate
35
and the magnetic plate
36
. A circular recess cavity
34
(refer to
FIG. 1
) remains even after the magnetic disk
36
and the metal disk
35
are slipped into the recess cavity
37
in sequence. As mentioned before, the cavity
34
is used for housing the circular magnetic generator on the acoustic diaphragm assembly
14
.
In addition, there is a stationing hole
39
in the center of the recess cavity
37
for fixing the magnetic plate
36
via the base block
38
with a guiding pin (not shown) from below. A few concentric grooves (not shown) of different sizes are also formed on the bottom surface of the base block
38
. These concentric grooves are aids for dissipating the heat generated by the speaker. Without any mechanism for dissipating the heat, the magnetic plate
36
may rise to a temperature over 120° C. resulting in its demagnetization. Since the base block
38
is formed in a single piece, exposed surfaces are quite limited. Hence, its heat dissipation capacity is intrinsically poor. Furthermore, due consideration must be made regarding the design of cavity
37
so that excessive magnetic flux leakage is prevented. This leakage occurs because some material on the opposite side of the cavity must be carved away to form the concentric grooves. Hence, the base block
38
is harder and more costly to build.
SUMMARY OF THE INVENTION
Accordingly, the purpose of the present invention is to provide a multi-plate metal base assembly for a speaker. All the component plates of the assembly are easy to produce and simple to assemble so that the assembly can be fabricated by most manufacturers at a reasonable cost. Moreover, the multi-plate design of the metal base is able to increase the effective area for dissipating heat away from the interior of the speaker.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention provides a metal base assembly for a speaker. The metal base assembly is part of a magnetic circuit for producing a variable magnetic field. The magnetic field in turn induces an acoustic diaphragm to vibrate, thereby producing a high tone sound. The metal base assembly includes a top pad, a middle pad, a bottom plate, a plurality of positioning rivets, a magnetic plate and a metal plate.
The top pad is a circular metallic disk with a hole in the middle. The top pad has a plurality of positioning holes. The middle pad ring is also a circular metallic disk with a hole in the middle. The middle pad has a plurality of positioning holes that match the positioning holes of the top pad. The bottom plate is a circular metallic disk having, around its periphery, a plurality of positioning holes that match the positioning holes of the middle pad ring. The rivets pass through the positioning holes the bottom plate as well as through the positioning holes of the second pad and terminate inside the positioning holes of the top pad. Hence, a metal base with a recess cavity is formed. The recess cavity is formed out of the central holes of the top pad and the middle pad.
The magnetic plate and the metal plate are sequentially placed inside the recess cavity of the metal base. The magnetic plate is used for generating a variable magnetic field while the metal plate is used for containing the magnetic plate.
The rivets are designed to pass through the positioning holes of the bottom plate and the middle pad and to be locked inside the positioning holes of the top pad. Both the middle hole of the top pad and the middle hole of the middle pad have the same diameter but are slightly larger than the diameter of the circular magnetic plate and the circular metal plate. Therefore, the circular magnetic plate and the circular metal plate can be slipped inside the holes. Furthermore, the top pad, the middle pad and the bottom plate are designed to have the same external diameter. In addition, the magnetic plate can be stationed by an external positioning pin passing through an additional positioning hole in the middle of the bottom plate.
The metal base assembly can be used together with various types of speakers installed inside a car, a motorcycle and even a house. The metal base together with a speaker casing, a mounting block, an acoustic diaphragm assembly and a plastic pad form a speaker unit. T
Alertek Corporation
Harvey Dionne N.
Huang Jiawei
J.C. Patents
Kuntz Curtis
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