JPS6325840Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an electric megaphone whose output transistor of an amplifier is not easily deteriorated by heat, and which can be miniaturized.

Conventionally, electric megaphones consist of a horn speaker, an amplifier circuit housed in a cylindrical amplifier case following the horn speaker, a battery, a microphone, etc., and are designed to be waterproof so that they do not malfunction even when used in the rain. ing.

Therefore, heat dissipation from the output transistor of the amplifier is done by a small heat dissipation plate installed inside the amplifier case, which is sealed to make it waterproof, and the heat dissipation effect is low, causing early deterioration or thermal destruction of the output transistor. Sometimes.

Further, it is desirable to make the electric megaphone as small as possible, but the provision of this heat sink makes it difficult to downsize, and when miniaturized, the heat sink becomes smaller, resulting in a reduction in output.

This invention attempts to eliminate the above drawbacks by forming the horn of the horn speaker from a material with good heat dissipation and thermal conductivity, and thermally coupling the output transistor of the amplifier to this horn. .

This invention will be explained below based on illustrated embodiments.

FIG. 1 shows a first embodiment of this invention, in which reference numeral 2 represents a horn speaker, and an amplifier case 4 is integrally attached to the rear of the horn speaker 2. The horn speaker 2 is composed of a horn 6 and a drive unit 8, and the horn 6 further includes an outer cylinder 10,
It is composed of a middle cylinder 12 and an inner cylinder 14. At least the outer cylinder 10 of the horn 6 is made of a metal such as aluminum die-casting having good heat dissipation and thermal conductivity, and its rear end is bent inward to form a flange portion 16.

On the back side of the flange portion 16, a throat member 18 to which the drive unit 8 is attached is arranged via a rubber packing 20 which is a poor conductor of heat.

Further, on the front side of the flange portion 16, a heat dissipation ring 22 made of a material with good thermal conductivity is arranged and coated with silicone grease. Heat dissipation ring 2
2 has a tongue portion 24 extending from a portion of the inside toward the center, as shown in FIG.

The tongue portion 24 is bent into a crank shape in order to avoid the drive unit 8, and an output transistor 28 attached to a substrate 26 forming an amplifier circuit is attached to the end of the tongue portion 24 after being coated with silicone grease. It is attached by 30.

The heat dissipation ring 22 is connected to the flange portion 3 of the amplifier case 4 via the rubber ring 32, which is a poor conductor of heat.
4, and a screw 36 is inserted from the back side of this flange portion 34 into the flange portion 34, the rubber ring 32,
These parts are integrally connected by passing through the heat radiation ring 22 and the flange part 16 and screwing into the throat tool 18. In FIG. 1, 38 is a handle, and 40 is a battery.

In the electric megaphone constructed in this manner, heat generated by the output transistor 28 during use is transmitted to the outer case 10 via the heat radiation ring 22 and is dissipated into the air. Since the outer cylinder 10 is always in contact with the outside air and has a large area, heat is efficiently dissipated. Furthermore, heat dissipation is promoted when sound waves pass inside the outer cylinder, and this effect increases as the output increases, so it is possible to prevent the output transistor 28 from deteriorating or being destroyed by heat.

Furthermore, the heat of the heat dissipation ring 22 is transferred to the rubber ring 32.
The heat is blocked by the rubber packing 20 and is not transmitted to the amplifier case 4, the throat tool 18, and the drive unit 8, but is transmitted only to the outer cylinder 10, so the parts inside the amplifier case 4 and the drive unit 8 deteriorate due to heat. Never. Furthermore, since the heat sink does not need to be housed within the amplifier case, the amplifier case 4 itself can be downsized.

FIG. 3 shows a second embodiment of this invention, in which the same parts as in the first embodiment are designated by the same reference numerals and their explanation will be omitted.

As shown in FIG. 3, the output transistor 28 is coated with silicone grease and is directly attached to the circumferential surface of the outer cylinder 10 with screws 42, and the lead wire 44 is extended and inserted into a small hole provided on the circumferential surface of the amplifier case 4. 46 and is connected to the board 26.

In addition, the outer cylinder 10 and the amplifier case 4 are straddled,
Waterproof case 48 that protects the output transistor 28
is installed.

The electric megaphone configured in this manner has a high heat dissipation effect because the output transistor 28 is directly attached to the outer cylinder 10, and since there is no output transistor 28 that generates heat inside the amplifier case 4, the heat dissipation effect is high. The temperature never rises.

As explained above, according to this invention, the output transistor 28 is connected to the outer tube 1, which has a large area exposed to the outside air and has good heat dissipation and thermal conductivity.
Since it is thermally coupled to 0, it has a high heat dissipation effect,
By omitting the heat sink that was conventionally provided inside the amplifier case 4, it is possible to reduce the size and obtain a heat dissipation effect equivalent to or better than that achieved by providing a heat sink inside the amplifier case 4. Therefore, it is possible to prevent the output transistor 28 from being prematurely deteriorated or destroyed by heat. Moreover, the outer cylinder 10 to which the output transistor 28 is thermally coupled is
A rubber gasket 20 that is a thermally poor conductor with the throat tool 18, drive unit 8, and amplifier case 4;
Since it is blocked by the rubber ring 32, the heat of the output transistor 28 conducted to the outer cylinder 10 is not transferred to the throat tool 18 or the amplifier case 4. Therefore, the throat tool 18 and the drive unit 8
Also, the components of the amplifier circuit 26 inside the amplifier case 4 are not destroyed by heat.

In addition, as a structure in which an output transistor is thermally coupled to the components constituting a megaphone, the
There is also one disclosed in Publication No. 23429.
This has an outer cylinder and an amplifier case integrally formed of synthetic resin, partitioned by a drive section, and an output transistor thermally coupled to a yoke cup of the drive section. However, in this case, the output transistor is thermally coupled to the yoke cup, so
The heat is radiated into the amplifier case, and the components of the amplifier circuit inside the amplifier case may be destroyed by the heat. However, in this invention, as described above, the outer tube 1 to which the output transistor is attached is
0 is isolated from the amplifier case 4 and the throat tool 18 by the rubber packing 20 and the rubber ring 32, respectively, so the above-mentioned problem does not occur.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of the first embodiment of this invention;
FIG. 2 is a plan view of a heat dissipation ring used in the same embodiment, and FIG. 3 is a longitudinal sectional view of a second embodiment of this invention. {8... Drive unit, {10... Outer cylinder, 12
...Middle tube, 14...Inner tube}6...Horn}2...
Horn speaker}, 4...Amplifier case, 22...
...heat dissipation ring, 26...amplifier circuit, 28...output transistor.

Claims (1)

[Scope of utility model registration request] A horn speaker in which the horn is formed of a material with high heat dissipation and heat conductivity, and a throat member to which a driving unit is coupled is disposed within the horn via a first poor conductor of heat, and the horn speaker The amplifier case attached to the rear of the
A second thermally defective conductor interposed between the horn speaker and the amplifier case, and an amplifier circuit provided in the amplifier case to amplify the sound supplied from the microphone and supply it to the drive unit. , an electric megaphone comprising: an output transistor of the amplifier circuit thermally coupled to the horn.