JP2600785Y2 - Alarm - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alarm device and, more particularly, to an improvement in the structure of an alarm device which can effectively prevent a decrease in alarm sound when the apparatus is flooded.

[0002]

2. Description of the Related Art An alarm using a piezoelectric diaphragm excellent in water resistance is used as an external buzzer such as a back buzzer when the vehicle is moving backward. FIGS. 3 and 4 show examples.

[0003] In the figure, a housing 1 of an alarm device has a front circular shape and is attached to a rear lower surface of a vehicle body or the like by a bracket 3 projecting upward from a side surface. The front portion of the housing 1 has a truncated frustum shape whose diameter is reduced forward, and sound emitting holes 12 and 18 are provided at a plurality of locations on the outer peripheral portion on the front surface. The sound output hole 12 at the lower end has a large diameter and also serves as a drain hole.

The details of the alarm will be described with reference to FIGS.
A cylindrical wall 19 protrudes inward from the back surface of the front wall 17 of the housing 1, and the metal diaphragm 2 is attached so as to close the inner end opening. A piezoelectric ceramic 21 sandwiched between electrode plates is adhered to the vibration plate 2, and the vibration plate 2 vibrates by being energized through a lead wire 22.

The in-cylinder space closed by the diaphragm 2 is the resonance chamber 1
The sound emitted from the diaphragm 2 is resonantly amplified and transmitted through the sound output holes 12 and 18. As described above, the lower sound emitting hole 12 has a large-diameter inverted U shape, and the other sound emitting holes 18 have a small-diameter circular shape. In addition, the resonance chamber bottom surface 16 of the part reaching the sound emission hole 12 is inclined downward,
The water that has entered the resonance chamber 1a is guided to the sound emission hole 12 which also serves as a drain hole.

[0006]

In the above-mentioned conventional structure, the diaphragm 2 using the piezoelectric ceramics 21 has water resistance, and the sound emission hole 12 at the lower end is used as a drain hole to allow water to enter during rainfall or car washing. However, there is a problem that the warning sound is reduced when it is flooded. According to the knowledge of the inventor and the like, this is due to the fact that a water film is formed on the sound emitting holes 12 and 18 when the sound is received.

Accordingly, the present invention is to solve such a problem, and an object of the present invention is to provide an alarm device which can prevent a sound emission hole from being closed by a water film with a simple structure and can prevent a reduction in an alarm sound when being wet. And

[0008]

To explain the structure of the present invention, a resonance chamber 1a is provided in a housing 1 and a sound emission hole 11 is provided in a chamber wall of the resonance chamber 1a which is shared with a front wall of the housing 1.
12 are formed, and peripheral portions 13 and 14 of the sound emission holes 11 and 12 are formed.
Is thinner than the wall thickness d2 of the remaining front wall 17 general portion.

[0009]

In the above construction, since the peripheral portions 13 and 14 of the sound emission holes 11 and 12 have a reduced wall thickness, the length of the holes becomes short, and water does not accumulate and a film is not formed. Moreover, even if it is compared, since the film thickness is thin, it is quickly broken by vibration or the like. Therefore, the problem that the alarm sound is lowered does not occur.

Since the wall thickness is reduced only at the peripheral portions 13 and 14 of the sound emission holes 11 and 12, the strength of the housing 1 does not decrease.

[0011]

1 and 2, the basic structure of the alarm device is the same as the conventional structure described above, and the following description will focus on the differences.

A cylindrical wall 19 projecting inward from the back surface of the front wall 17 of the housing 1 has an opening closed by the diaphragm 2 to form a resonance chamber 1a. The circular front wall 17 also serving as a chamber wall of the resonance chamber 1a is provided with a circular sound output hole 11 at a position eccentric slightly upward from the center, and has a hole area of a conventional sound output hole 18 (see FIG. 6). ) Is approximately equal to the sum of the respective hole areas.

The peripheral portion 13 of the sound output hole 11 has an inverted U-shaped region (FIG. 2) as viewed from the front, which is recessed stepwise from the general portion of the front wall 17 and has a wall thickness d1 of the wall of the general portion. It is thinner than the thickness d2. Therefore, the sound emitting hole 11 penetrating therethrough has a sufficiently short hole length. In addition, only the lower side of the peripheral portion 13 is continuous with the general portion on the inclined surface 15.

An inverted U-shaped sound emission hole 12 also serving as a drainage hole is provided at the lower end of the front wall 17 below the sound emission hole 11, and a peripheral portion 14 having a constant width excluding a lower side to be opened is recessed stepwise. It is thin. The tip of the bottom surface 16 of the resonance chamber 1a that slopes down reaches the lower side that is open.

When the piezoelectric ceramics 21 of the diaphragm 2 is energized, it vibrates and emits a sound, which is resonance-amplified in the resonance chamber 1a and transmitted from each of the sound emission holes 11 and 12 as an alarm sound.

If water is received during use, each of the sound output holes 11, 1
The water that has entered the housing from 2 is guided to the resonance chamber bottom surface 16 that is inclined downward and is discharged from the sound emission hole 12. At this time, the water flowing down the surface of the housing is dissipated in each sound emitting hole 11,1.
In both cases, the pore length is sufficiently short.
It does not accumulate here and form a film. Further, even if a parable film is formed, the film is sufficiently thin, so that it is quickly broken by vibration or the like. Thus, since the sound emission holes 11 and 12 are not blocked by the water film, there is no problem that the alarm sound is lowered when the sound is wet.

The lower side of the sound emitting hole peripheral portion 13 is the inclined surface 1.
Since it is set to 5, the water here is allowed to flow down quickly without pooling.

In this embodiment, a plurality of conventional small-diameter sound emitting holes 1 are used.
8 (see FIG. 6) are collectively formed into a single large-diameter sound emission hole 11, so that the water film is not easily stretched and the stretched film is easily broken.

Since the wall thickness is reduced only around the sound output holes 11 and 12, the strength of the housing 1 does not decrease. In addition, the resonance characteristics of the resonance chamber 1a do not deteriorate because the change due to the thinning can be corrected by the sound emission hole area.

If the resonance characteristics allow, the sound output holes 11
May be collected in the sound emission hole 12.

[0021]

[Effects of the Invention] As described above, according to the alarm of the present invention,
With a simple structure, it is possible to prevent the alarm sound from being lowered when it is wet, and it can be suitably used as an outside buzzer such as a back buzzer of a vehicle.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an alarm housing showing one embodiment of the present invention.

FIG. 2 is a front view of the alarm housing.

FIG. 3 is an overall front view of a conventional alarm device.

FIG. 4 is an overall side view of a conventional alarm device.

FIG. 5 is a longitudinal sectional view of a conventional alarm housing.

FIG. 6 is a front view of a conventional alarm housing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Housing 1a Resonance chamber 11, 12 Sound emission hole 13, 14 Peripheral part 17 General part 2 Diaphragm

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Koichi Sugiyama 3 Iyama, Shinome-cho, Anjo-shi, Aichi Prefecture Inside Anden Co., Ltd. (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G10K 9/22 G10K 9/12 G10K 9/122 G10K 9/13 G10K 9/15

Claims (1)

(57) [Scope of request for utility model registration] 1. A front wall in which a resonance chamber is provided in a housing, a sound emission hole is formed in a chamber wall of the resonance chamber shared with a front wall of the housing, and a wall thickness of a peripheral portion of the sound emission hole remains. An alarm device characterized by being thinner than the wall thickness of the part.