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JP2016024796

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
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DESCRIPTION JP2016024796
The present invention provides a portable gas detector capable of outputting a sound wave of a
predetermined frequency to the outside with a sufficient sound pressure. A portable gas detector
(100) includes a gas detection unit for detecting a gas to be detected, and a diaphragm (4a) that
vibrates to generate a sound wave when reporting gas detection by the gas detection unit. In
addition, the portable gas detector 100 includes a circular first recess 16 and an annular second
recess 17 formed so as to surround the first recess 16, and the first recess 16 and the second
recess are formed. The cover 4 is provided with a first acoustic space A1 corresponding to the
first recess 16 and a second acoustic space A2 corresponding to the second recess 17 by fixing
the diaphragm 4a so as to cover 17. . [Selected figure] Figure 6
Portable gas detector
[0001]
The present invention relates to a portable gas detector, and more particularly to a portable gas
detector provided with a diaphragm for generating an acoustic wave.
[0002]
BACKGROUND Conventionally, a portable gas detector provided with a diaphragm that generates
sound waves is known (see, for example, Patent Document 1).
[0003]
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1
Patent Document 1 discloses a portable gas detector including a warning buzzer including a
piezoelectric vibrator (diaphragm) for generating a sound wave and a case.
In the case of the alarm buzzer of the portable gas detector described in Patent Document 1
described above, the sound emission port is formed on one side in a predetermined direction, and
the end of the piezoelectric vibrator is fixed on the other side. There is.
As a result, one acoustic space is formed by the piezoelectric vibrator and the case on the sound
output side of the piezoelectric vibrator in the alarm buzzer.
[0004]
JP, 2013-125601, A
[0005]
However, in the portable gas detector described in Patent Document 1 described above, since
only one acoustic space is formed by the piezoelectric vibrator and the case in the alarm buzzer,
the piezoelectric vibrator generates the acoustic space in the one acoustic space. Of the
frequencies of the sound waves generated, it is considered that sufficient resonance can not be
achieved at a predetermined frequency that is easy for humans to sense.
As a result, it is considered that there is a problem that it is difficult to output a sound wave of a
predetermined frequency to the outside of the portable gas detector with a sufficient sound
pressure.
[0006]
The present invention has been made to solve the problems as described above, and one object of
the present invention is to provide a portable gas capable of outputting a sound wave of a
predetermined frequency with sufficient sound pressure. It is providing a detector.
[0007]
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2
A portable gas detector according to one aspect of the present invention includes a gas detection
unit that detects a gas to be detected, and a diaphragm that vibrates to generate a sound wave
when notifying gas detection by the gas detection unit.
In addition, the portable gas detector includes a circular first recess and an annular second recess
formed so as to surround the first recess, and vibrates to cover the first recess and the second
recess. A diaphragm fixing portion is formed in which a first acoustic space corresponding to the
first recess and a second acoustic space corresponding to the second recess are formed by fixing
the plate.
[0008]
In the portable gas detector according to one aspect of the present invention, as described above,
by fixing the diaphragm so as to cover the first recess and the second recess, the first acoustic
space corresponding to the first recess and A diaphragm fixing portion is provided in which a
second acoustic space corresponding to the second recess is formed. Thus, by providing not only
the first acoustic space but also the second acoustic space, the acoustic wave generated by the
diaphragm can be sufficiently resonated at a predetermined frequency that is easily sensed by a
person. Can be output to the outside of the portable gas detector with sufficient sound pressure.
In addition, this effect has been confirmed by the sound pressure measurement (Example)
mentioned later.
[0009]
In the portable gas detector according to the aforementioned aspect, preferably, the diaphragm
fixing portion is provided with a third recess formed on the surface opposite to the surface on
which the first recess is formed, a third recess, and a first And an internal sound emitting hole
connecting the recess. According to this structure, the third concave portion can suppress the
attenuation of the sound wave output from the first concave portion through the internal sound
emission hole, so that the predetermined frequency which can be easily detected by a person can
be reliably determined. Can be output to the outside of the portable gas detector with sufficient
sound pressure. Further, by providing the third recess on the surface opposite to the surface on
which the first recess of the diaphragm fixing portion is formed, compared to the case where the
third recess is provided in a member different from the diaphragm fixing portion, As a separate
member is not provided, the portable gas detector can be prevented from increasing in size in the
direction in which the internal sound emission hole extends, and an increase in the number of
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3
parts can be suppressed. In addition, since the portable gas detector is mainly carried by the
user, miniaturization is particularly desired, and from that point, it is particularly required to
suppress the enlargement.
[0010]
In this case, preferably, the diaphragm is fixed to a region other than the region corresponding to
the third recess, of the surface on the opposite side to the surface on which the first recess of the
diaphragm fixing portion is formed, The diaphragm fixing portion further includes a panel
portion covering the recess so that the recess is not exposed to the outer surface, and the panel
fixing portion is attached to the diaphragm fixing portion so as to cover the third recess. 3 Sound
space is formed. According to this structure, the sound wave output from the first recess to the
third recess through the internal sound emission hole can be sufficiently suppressed from being
attenuated in the third recess by the third acoustic space. More reliably, sound waves of a
predetermined frequency can be output to the outside of the portable gas detector with sufficient
sound pressure. As a result, even when no sound output hole is provided in the panel portion
covering the third concave portion, sound waves of a predetermined frequency can be output to
the outside of the portable gas detector with a sufficient sound pressure. Further, since the panel
portion can suppress the internal sound emitting hole and the third recess from being exposed to
the outer surface, foreign matter such as water or dust which has entered from the internal
sound emitting hole adheres to the diaphragm. It can be suppressed. As a result, it is possible to
suppress that the frequency of the sound wave generated from the diaphragm deviates from the
predetermined frequency that is easily sensed by a person, and that the sound pressure of the
sound wave is reduced.
[0011]
Preferably, the portable gas detector according to the above aspect further includes a display
screen unit, and the display screen unit is attached to the diaphragm fixing unit in addition to the
fixing of the diaphragm. According to this structure, since the diaphragm fixing portion can be
used for mounting the display screen portion in addition to fixing of the diaphragm, parts for
mounting the display screen portion are not necessary. This can suppress an increase in the
number of parts.
[0012]
According to the present invention, as described above, sound waves of a predetermined
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4
frequency can be output to the outside of the portable gas detector with a sufficient sound
pressure.
[0013]
FIG. 1 is a perspective view showing the overall configuration of a portable gas detector
according to an embodiment of the present invention.
FIG. 5 is a block diagram illustrating a control configuration of a portable gas detector according
to an embodiment of the present invention. FIG. 6 is a perspective view showing the use of the
portable gas detector according to one embodiment of the present invention. FIG. 1 is a front
exploded perspective view of a portable gas detector according to an embodiment of the present
invention. It is the disassembled perspective view which looked at the cover part of the portable
gas detector by one Embodiment of this invention, the diaphragm, and the display screen part
from back. It is sectional drawing along the 400-400 line of FIG. It is the fragmentary sectional
view which showed the internal structure of the portable gas detector of Example 1-2 of 1st
Example in the sound pressure measurement performed in order to confirm the effect of this
invention. It is the fragmentary sectional view showing the internal structure of the portable gas
detector of comparative example 1 of comparative example 1 of the 1st example in sound
pressure measurement performed in order to confirm the effect of the present invention. It is the
table | surface which showed the measurement result of 1st Example in the sound pressure
measurement performed in order to confirm the effect of this invention. It is the fragmentary
sectional view which showed the internal structure of the portable gas detector of Example 2-2 of
2nd Example in the sound pressure measurement performed in order to confirm the effect of this
invention. It is the table | surface which showed the measurement result of 2nd Example in the
sound pressure measurement performed in order to confirm the effect of this invention. It is the
table | surface which showed the measurement result of 3rd Example in the sound pressure
measurement performed in order to confirm the effect of this invention. It is the table | surface
which showed the measurement result of 4th Example in the sound pressure measurement
performed in order to confirm the effect of this invention.
[0014]
Hereinafter, an embodiment of the present invention will be described based on the drawings.
[0015]
First, the entire configuration of a portable gas detector 100 according to an embodiment of the
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5
present invention will be described with reference to FIGS. 1 to 3.
[0016]
A portable gas detector 100 according to an embodiment of the present invention shown in FIG.
1 detects a predetermined detection target gas (isobutane, methane, hydrogen, etc.) around the
portable gas detector 100, and has a predetermined concentration or more. It is a gas detector
for notifying the user that the concentration of the detection target gas in the surrounding
atmosphere is high due to a gas leak or the like by outputting an alarm when the detection target
gas is detected.
In addition, the portable gas detector 100 has a dustproof / waterproof function, and the entry of
water, dust, etc. into the interior of the portable gas detector 100 is suppressed.
[0017]
As shown in FIG. 2, the portable gas detector 100 includes a gas detector 1, a controller 2, three
input buttons 3 (see FIG. 1), a buzzer 4, and two lamps 5 (see FIG. 1). And the display screen unit
6).
[0018]
The gas detection unit 1 detects the concentration of the detection target gas by using the
change in the electrical conductivity of the detection piece according to the temperature rise
when the detection target gas (flammable gas) burns, a contact not shown It includes a
combustion type gas sensing element.
In addition, as a gas detection element of the gas detection part 1, you may use not only a contact
combustion type gas detection element but a different gas detection element according to
detection object gas.
For example, a semiconductor gas detection element may be used as the gas detection element of
the gas detection unit 1.
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[0019]
The control unit 2 includes a CPU, and is configured to control the entire portable gas detector
100 by executing an operation program stored in a storage unit (not shown). Further, the control
unit 2 is configured to output an alarm for notifying that the detection target gas has exceeded a
predetermined concentration from the buzzer 4, the two lamps 5, and the display screen unit 6 at
the time of an alarm. Specifically, at the time of alarming, the control unit 2 causes the buzzer 4
to output a predetermined buzzer sound and turns on a lamp of a predetermined color in the
lamp 5 to notify the user of the alarm. It is configured. The control unit 2 is configured to be able
to display predetermined information such as the concentration of the gas to be detected on the
display screen unit 6 at the time of an alarm. At the time of calibration of the portable gas
detector 100, the control unit 2 can display the calibration result and the like on the display
screen unit 6, so that the user can confirm the calibration result and the like.
[0020]
Further, the input button 3 is provided to receive an input operation by the user such as turning
on / off of the power supply of the portable gas detector 100, and a storage instruction of the
calibration result.
[0021]
Further, as shown in FIG. 3, the portable gas detector 100 is configured to be able to attach a clip
7 for attaching to the belt 101, chest pocket of a user, and a helmet (not shown).
Thus, the user can easily carry the portable gas detector 100.
[0022]
Next, the specific structure of the portable gas detector 100 will be described with reference to
FIGS. 1, 2 and 4 to 6.
[0023]
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7
As shown in FIG. 1, the portable gas detector 100 includes a main body 10 and a sensor cap
member 20 and a battery unit 30 which are detachably mounted to the main body 10.
The sensor cap member 20 is attached to a side surface on one side (X2 side) of the main body
portion 10 in the longitudinal direction (X direction). The battery unit 30 is attached to the back
surface (Y2 side) of the main body 10 in the front-rear direction (Y direction).
[0024]
Further, in the state where the battery unit 30 is attached to the main body portion 10, the
portable gas detector 100 is formed in a substantially rectangular parallelepiped shape, and each
corner of the rectangular parallelepiped is R-chamfered.
[0025]
Further, as shown in FIG. 4, the main body portion 10 includes a housing 11, a substrate portion
12 and a cover portion 13 disposed inside the housing 11, a double-sided adhesive tape 14, and
a panel portion 15. .
Further, the substrate portion 12 is configured to be fixed to the rear side (Y2 side) of the cover
portion 13. Further, as shown in FIG. 5, on the rear surface 13a of the cover portion 13, a
diaphragm 4a that vibrates to generate a sound wave when notifying gas detection by the gas
detection portion 1 and a display screen portion 6 are attached. ing. The detailed attachment
structure will be described later.
[0026]
The diaphragm 4a is composed of a piezoelectric element (not shown) such as PZT, and a pair of
electrodes 104a formed so as to sandwich the piezoelectric element. The diaphragm 4a is
configured to vibrate in the front-rear direction (Y direction) by applying a predetermined
electric signal from the control unit 2 (see FIG. 2) to the pair of electrodes 104a. As a result, the
air is vibrated based on the vibration of the diaphragm 4a, whereby a sound wave is generated
from the diaphragm 4a. The diaphragm 4 a constitutes a part of the buzzer 4.
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8
[0027]
The display screen unit 6 has a pair of conductive rubbers 6a made of zebra rubber or the like
attached to the rear, and a display area 6b in which an image such as predetermined information
is displayed by the control unit 2 (see FIG. 2). There is. The pair of conductive rubbers 6a are
fixed to the upper side (Z1 side) and the lower side (Z2 side) of the display screen section 6,
respectively. The display screen unit 6 is attached to the rear surface 13a of the cover unit 13 so
that an image is displayed on the front side (Y1 side) in the display area 6b.
[0028]
The housing 11 is formed in a box shape having an open front side (Y1 side) as shown in FIGS. 4
and 6. The base 12 and the cover 13 are housed in the housing 11 a formed inside the housing
11.
[0029]
As shown in FIG. 6, the substrate unit 12 is combined such that a plurality of substrates 12 a are
stacked in the front-rear direction (Y direction), and a CPU constituting the control unit 2 is
attached. In addition, the wiring (not shown) of the diaphragm 4a (see FIG. 5) is connected to the
frontmost (Y1 side) substrate 12a, and the display screen section 6 is connected via the pair of
conductive rubbers 6a. . As a result, the diaphragm 4a and the display screen 6 are respectively
driven via the wiring and the pair of conductive rubbers 6a. Insulating sheets 12b for securing
insulation between the substrates 12a are disposed between the substrates 12a.
[0030]
The cover 13 is made of transparent resin. Further, as shown in FIGS. 4 and 5, the cover portion
13 is formed in a rectangular shape extending in the longitudinal direction (X direction) and the
up and down direction (Z direction), and the side portion is substantially from the entire outer
edge portion. It is formed to extend toward the rear side (Y2 side).
[0031]
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9
Here, in the present embodiment, as shown in FIG. 5, the rear surface 13a of the cover 13 has an
annular wall 13b and a diameter larger than that of the annular wall 13b and the wall 13b. On
the other hand, an annular wall portion 13c formed concentrically is formed. The wall portions
13b and 13c are both formed to project rearward (in the Y2 direction) from the rear surface 13a
of the cover portion 13. As a result, the rear surface 13a of the cover 13 is formed on the inside
of the wall 13b, and the circular first recess 16 seen in plan from the rear, and the inside of the
wall 13c and of the wall 13b An annular second recess 17 is provided that is formed on the
outside and viewed in plan from the rear.
[0032]
Further, on the inner side (the second concave portion 17 side) of the outer wall portion 13c, a
step portion 113c for fixing the diaphragm 4a is formed over the entire circumference of the wall
portion 13c. As shown in FIG. 6, the step portion 113c is formed on the rear side of the end
portion on the rear side (Y2 side) of the inner wall portion 13b. The diaphragm 4a is adhered and
fixed to the step portion 113c from the rear side so as to cover the first concave portion 16 and
the second concave portion 17 from the rear side. The entire outer peripheral edge of the
diaphragm 4a is fixed to the entire periphery of the circumferential step portion 113c. In
addition, a gap is formed between the diaphragm 4a and the wall portion 13b by positioning the
step portion 113c on the rear side of the rear end of the inner wall portion 13b.
[0033]
As a result, the space formed by the first recess 16 and the diaphragm 4a (the space formed by
the wall 13b, the bottom surface 16a, and the diaphragm 4a) becomes the first acoustic space
A1, and the second recess 17 The portable gas detector 100 is configured such that the space
(the space formed by the wall portions 13b and 13c, the bottom surface 17a, and the diaphragm
4a) formed by the first and the diaphragm 4a is the second acoustic space A2. It is done. The first
acoustic space A1 and the second acoustic space A2 are connected to each other via a gap
between the wall 13b and the diaphragm 4a.
[0034]
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10
In the first acoustic space A1 and the second acoustic space A2, among the frequencies of the
sound waves based on the vibration generated in the diaphragm 4a, the sound waves of about 3
kHz, which are frequencies easy to be detected by a person, resonate. In particular, in the second
acoustic space A2, a sound wave of about 3 kHz is resonated. As a result, it is possible to output
the sound pressure of a sound wave having a frequency of about 3 kHz with a sufficient
magnitude from an internal sound emission hole 13 d described later. In general, a frequency
that human beings can easily sense is about 3 kHz or more and about 4 kHz or less.
[0035]
Further, as shown in FIG. 6, the bottom surface 16 a on the front side (Y 1 side) of the first recess
16 is formed in a flat surface shape. Further, the bottom surface 17a on the front side of the
second recess 17 is provided to be inclined forward from the inner wall portion 13b to the outer
wall portion 13c. Under the present circumstances, in the bottom 17a of the 2nd crevice 17, the
bottom 17a by the side of inner wall 13b is located in the back side (Y 2 side) rather than bottom
16a of the 1st crevice 16, and the bottom in the side of outside wall 13c The reference numeral
17 a is formed on the front side of the bottom surface 16 a of the first recess 16. The bottom
surface 17 a is formed to be inclined in substantially the same direction as the inclined portion
18 b of the third concave portion 18 described later.
[0036]
Further, an internal sound emission hole 13 d is formed substantially at the center of the bottom
surface 16 a of the first recess 16. The inner sound emission hole 13 d penetrates the cover
portion 13 in the front-rear direction (Y direction) so as to connect the rear surface 13 a of the
cover portion 13 and the front surface 13 e. As a result, sound waves generated in the diaphragm
4a and resonated in the first acoustic space A1 and the second acoustic space A2 are output from
the internal sound emission holes 13d to the front surface 13e side (front side, Y1 side) of the
cover portion 13. It is configured to be. The inner sound release hole 13d has an inner diameter
R1 of about 2 mm.
[0037]
Further, in the present embodiment, as shown in FIG. 6, in the region corresponding to the first
recess 16 and the second recess 17 in the front surface 13 e of the cover portion 13, the third
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11
recess 18 is formed. As shown in FIG. 4, the third recess 18 is formed in a circular shape in plan
view from the front (the Y1 direction). The third recess 18 is formed so as to surround the flat
bottom 18a and the bottom 18a, and is inclined rearward (Y2) from the outer edge of the third
recess 18 toward the bottom 18a (inward). And an inclined portion 18b. Further, an internal
sound emission hole 13 d connected to the bottom surface 16 a of the first recess 16 is provided
substantially at the center of the bottom surface 18 a of the third recess 18.
[0038]
Further, as shown in FIG. 6, the substantially circular bottom surface 16a of the first concave
portion 16 and the substantially circular bottom surface 18a of the third concave portion 18 are
formed to overlap with each other when viewed from the front-rear direction (Y direction). It is
done. The bottom surface 16a of the first recess 16 and the bottom surface 18a of the third
recess 18 are both formed in a circle having a diameter R2 of about 13 mm in plan view. Further,
the annular outer edge portion of the second concave portion 17 and the annular outer edge
portion of the third concave portion 18 are formed so as to overlap each other when viewed from
the front-rear direction. The annular outer edge portion of the second recess 17 and the annular
outer edge portion of the third recess 18 are both formed in a circle having a diameter R3 of
about 17 mm in plan view.
[0039]
Further, as shown in FIG. 5, in the vicinity of the central portion of the rear surface 13a of the
cover portion 13, a display screen attaching portion 13f to which the display screen portion 6 is
attached is formed. The display screen mounting portion 13f is formed in a concave shape, and a
window portion 113f having a smaller thickness than the other region of the cover portion 13 is
formed at the center of the display screen mounting portion 13f. Then, the display screen unit 6
is fitted into the display screen mounting unit 13f, whereby the display screen unit 6b (see FIG.
1) is positioned at the position corresponding to the window unit 113f. 6 is configured to be
attached to the cover portion 13. Here, since the thickness of the window portion 113 f is smaller
than the thickness of the other region of the cover portion 13, the display region 6 b is protected
by the window portion 113 f, and the display on the display region 6 b from the outside of the
portable gas detector 100 is performed. It is possible to improve the visibility of the displayed
image.
[0040]
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12
Further, as shown in FIG. 4 and FIG. 5, the cover 13 is formed on the lower side (Z2 side) of the
display screen attaching part 13f, and a pair of holes 13g in which the detecting parts 3a of the
input button 3 are respectively disposed. And a hole 13 h formed on the X2 side of the display
screen mounting portion 13 f and in which the detection portion 3 a of the input button 3 is
disposed. The cover 13 is formed on the upper side (Z1 side) of the display screen mounting
portion 13f on the X2 side, and the hole 13i (see FIG. 4) in which the light emitting portion 5a
(see FIG. 2) of the lamp 5 is disposed. Have.
[0041]
The panel portion 15 is formed of a resin sheet having a thickness of about 0.2 mm through
which sound waves can pass. Further, as shown in FIG. 4, the panel portion 15 is formed in a
rectangular shape in plan view from the front-rear direction (Y direction). In addition, as shown
in FIG. 6, the panel unit 15 is provided with a double-sided adhesive tape 14 on the step portion
11 b circumferentially formed at the end of the front side (Y1 side) of the housing 11 and the
front surface 13 e of the cover 13. It is pasted through.
[0042]
Further, in the present embodiment, the panel unit 15 is not formed with a hole penetrating the
panel unit 15. That is, the panel unit 15 is disposed to cover the entire front surface 13 e of the
cover unit 13 from the front side (Y 1 side). As a result, as shown in FIG. 6, both the inner sound
emitting hole 13 d and the third recess 18 formed in the front surface 13 e of the cover portion
13 are configured not to be exposed to the outside of the portable gas detector 100 There is.
[0043]
In addition, the portable gas detection is performed so that the space formed by the third recess
18 and the panel portion 15 (the space formed by the bottom surface 18a, the sloped portion
18b and the panel portion 15) becomes the third acoustic space A3. The vessel 100 is
configured. In the third acoustic space A3, of the frequency of the sound wave based on the
vibration generated in the diaphragm 4a, a sound wave of about 3 kHz, which is a frequency easy
to be detected by a person, resonates. As a result, it is possible to transmit the sound pressure of
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the sound wave of a frequency of about 3 kHz with sufficient magnitude through the panel
portion 15 to the outside of the portable gas detector 100.
[0044]
In the portable gas detector 100 of the present embodiment, the sound wave is transmitted to
the outside of the portable gas detector 100 by the diaphragm 4a and the first acoustic space A1,
the second acoustic space A2, and the third acoustic space A3. A buzzer 4 for output is
configured.
[0045]
Further, as shown in FIG. 4, the double-sided tape 14 for attaching the panel unit 15 to the cover
unit 13 is formed in a rectangular shape in plan view from the front-rear direction (Y direction),
similarly to the panel unit 15. It is done.
Further, as shown in FIG. 6, in the double-sided adhesive tape 14, a hole 14 a is formed in a
region corresponding to the third concave portion 18 of the cover 13. That is, the double-sided
tape 14 is not located in the area corresponding to the third concave portion 18 of the cover
portion 13. The hole 14a of the double-sided adhesive tape 14 is formed in a circular shape
having a diameter R3 of about 17 mm in plan view. That is, the hole 14 a of the double-sided
adhesive tape 14 is formed in a circular shape having substantially the same size as the third
recess 18. Although the thickness in the front-rear direction (Y direction) of the double-sided
adhesive tape 14 is exaggerated in FIG. 6 for the sake of easy understanding, the actual thickness
of the double-sided adhesive tape 14 is Small enough.
[0046]
In the double-sided adhesive tape 14, holes in the region corresponding to the window 113f of
the display screen mounting portion 13f, the region corresponding to the pair of holes 13g and
13h, and the region corresponding to the pair of holes 13i 14b, 14c and 14d are formed.
[0047]
On the other hand, in the region other than the holes 14a to 14d of the double-sided tape 14, the
adhesive (hatched portion in FIG. 4) is applied over the entire area.
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That is, a region corresponding to the third recess 18 of the cover 13, a region corresponding to
the window 113f of the display screen mounting portion 13f, a region corresponding to the pair
of holes 13g and 13h, and a region corresponding to the pair of holes 13i Then, while the panel
portion 15 is not attached to the front surface 13 e of the cover portion 13, the panel portion 15
is attached to the front surface 13 e of the cover portion 13 in the other area. Thus, the front
surface 13e of the cover portion 13 and the step portion 11b of the housing 11 can be bonded to
the panel portion 15 in close contact with each other. Therefore, the front surface 13e of the
cover portion 13 and the step portion 11b of the housing 11 It is possible to prevent water and
dust from entering the inside of the housing 11 from the gap with the panel unit 15.
[0048]
Further, the housing 11 of the main body 10 and the housing of the sensor cap member 20 and
the battery unit 30 are both made of a resin to which a conductive material as an antistatic agent
is added. This can avoid the risk of ignition due to electrostatic charging.
[0049]
In the present embodiment, the following effects can be obtained.
[0050]
In the present embodiment, as described above, the first acoustic wave corresponding to the first
concave portion 16 is fixed by fixing the diaphragm 4a to the step portion 113c of the cover
portion 13 so as to cover the first concave portion 16 and the second concave portion 17. A
space A1 and a second acoustic space A2 corresponding to the second recess 17 are provided
around the first acoustic space A1.
As a result, the sound wave generated by the diaphragm 4a can be sufficiently resonated at a
predetermined frequency (about 3 kHz) that is easily sensed by a human, so a sound wave of the
predetermined frequency can be carried at a sufficient sound pressure. It can be output to the
outside of 100.
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[0051]
Further, in the present embodiment, by providing the third concave portion 18 on the front
surface 13 e opposite to the rear surface 13 a where the first concave portion 16 of the cover
portion 13 is formed, the internal sound emission hole 13 d is formed by the third concave
portion 18. Since it is possible to suppress the attenuation of the sound wave output from the
first recess 16 via the first concave part 16, the portable gas detection with a sound pressure of a
predetermined frequency (about 3 kHz) easy to be detected by a person with sufficient sound
pressure It can be output to the outside of the unit 100. Further, compared with the case where
the third recess 18 is provided in a member different from the cover portion 13, the portable gas
detector 100 is provided in the front-rear direction (Y direction) in which the internal sound
emitting hole 13d extends. The increase in size can be suppressed, and the increase in the
number of parts can be suppressed.
[0052]
Further, in the present embodiment, the third acoustic space A3 corresponding to the third
concave portion 18 is formed by affixing the panel portion 15 to the front surface 13e of the
cover portion 13 so as to cover the third concave portion 18. Thereby, the sound wave output
from the first concave portion 16 to the third concave portion 18 can be sufficiently suppressed
from being attenuated in the third concave portion 18 by the third acoustic space A3. More
reliably, sound waves of a predetermined frequency can be output to the outside of the portable
gas detector 100 with a sufficient sound pressure. Thereby, even if the sound release hole is not
provided in the panel portion 15 covering the third concave portion 18, the sound wave of the
predetermined frequency is output to the outside of the portable gas detector 100 with a
sufficient sound pressure. Can. In addition, the panel portion 15 can suppress the exposure of the
inner sound emitting hole 13d and the third concave portion 18 to the outer surface, so that
foreign matter such as water or dust intruding from the inner sound emitting hole 13d is the
diaphragm 4a. Can be inhibited from adhering to As a result, it is possible to suppress the
frequency of the sound wave generated from the diaphragm 4a from shifting from the
predetermined frequency (about 3 kHz) that is easily sensed by a person, and the reduction in
the sound pressure of the sound wave.
[0053]
Further, in the present embodiment, in addition to fixing the diaphragm 4 a, the display screen
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unit 6 is attached to the cover 13. Thus, the cover 13 can be used to attach the display screen 6
in addition to the fixing of the diaphragm 4a, so no parts for attaching the display screen 6 are
required. This can suppress an increase in the number of parts.
[0054]
Next, four types of sound pressure measurement (first to fourth examples) performed to confirm
the effects of the present invention will be described with reference to FIGS. 6 to 13.
[0055]
First Example In the first example, the second acoustic space A2 and the third acoustic space A3
are made different by changing the shape of the cover 13 of the portable gas detector 100 of the
above embodiment. The change in sound pressure was measured.
[0056]
Specifically, as Example 1-1, the same portable gas detector 100 as the above embodiment was
used.
That is, the portable gas detector 100 having all of the first acoustic space A1, the second
acoustic space A2 and the third acoustic space A3 as shown in FIG. 6 was used.
[0057]
Moreover, as Example 1-2, as shown in FIG. 7, while having the 1st acoustic space A1 and the
2nd acoustic space A2 same as the said embodiment, the inclination part 18b (two-dot chain line)
of the said embodiment is the same. The portable gas detector 100a having the third acoustic
space a3 constituted by the third concave portion 118 of the cover portion 113 not provided and
the panel portion 15 was used.
The cover portion 113 is an example of the “diaphragm fixing portion” in the present
invention.
04-05-2019
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[0058]
Further, as Comparative Example 1, as shown in FIG. 8, while having the same first acoustic
space A1 and third acoustic space A3 as the above embodiment, the second concave portion 17
(two-dot chain line) of the above embodiment is provided. As a result, the portable gas detector
200 in which the second acoustic space was not formed in the cover portion 213 was used.
[0059]
And the sound pressure of the sound wave from the portable gas detector of Example 1-1, 1-2
and the comparative example 1 was measured using the noise meter which does not show in
figure.
Specifically, the noise level meter is disposed to face the portion corresponding to the buzzer 4 of
the panel section 15 of the portable gas detector. At that time, the buzzer 4 and the noise level
meter were separated by 300 mm. Thereafter, a sound wave with a fixed frequency of 2.97 kHz
(about 3 kHz) was generated from the buzzer 4 (diaphragm 4a) of the portable gas detector, and
the sound pressure (dB) at that time was measured by a noise meter. And the difference of the
sound pressure of Example 1-2 and the comparative example 1 and the sound pressure of
Example 1-1 was calculated.
[0060]
The measurement results of the first embodiment are shown in FIG. From the measurement
results of the first embodiment, in the portable gas detector 100 of the embodiment 1-1 having
all the first acoustic space A1, the second acoustic space A2 and the third acoustic space A3,
sufficient sound of 80.8 dB is obtained. The pressure was measured. On the other hand, in
Comparative Example 1 in which the second acoustic space A2 was not formed, a sound pressure
of 76.6 dB, which is smaller by 4.2 dB than the sound pressure of Example 1-1, was measured. It
is considered that this is because the sound pressure of the sound wave of the fixed frequency of
2.97 kHz did not become large enough due to the absence of the second acoustic space A2. As a
result, it is possible to confirm that the sound pressure of the sound wave of the fixed frequency
of 2.97 kHz can be sufficiently increased by providing not only the first acoustic space A1 but
also the second acoustic space A2 around it. The
[0061]
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Further, in Example 1-2 having the third acoustic space a3 in which the inclined portion 18b
(two-dot chain line) is not provided, the sound pressure of 71.2 dB, which is 9.6 dB smaller than
the sound pressure of Example 1-1. Was measured. Thereby, it turned out that the inclination
part 18b of 3rd acoustic space A3 has a function which suppresses that the sound pressure of
the sound wave of the fixed frequency of 2.97 kHz attenuates. As a result, the portable gas
detector 100 of Example 1-1 having all of the first acoustic space A1, the second acoustic space
A2 and the third acoustic space A3 can maximize the sound pressure, which is preferable. found.
[0062]
Second Example Next, in the second example, changes in sound pressure and maximum
frequency due to the presence or absence of the inner wall 13b of the cover 13 of the portable
gas detector 100 of the above embodiment were measured. .
[0063]
Specifically, as Example 2-1, the same portable gas detector 100 as the above embodiment was
used as in Example 1-1.
That is, as shown in FIG. 6, the portable gas detector 100 in which the inner wall 13 b is provided
on the cover 13 is used.
[0064]
Moreover, as Example 2-2, as shown in FIG. 10, the transportable gas detector 100b in which the
inner wall part 13b (two-dot chain line) of the cover part 313 was not provided was used. Under
the present circumstances, the 1st recessed part 316 and the 2nd recessed part 317 were
divided by the division part 313j which does not protrude back side (Y2 side) rather than the
wall part 13b. In this case, the first acoustic space a1, which is a space formed by the first recess
316 and the diaphragm 4a (a space formed by the dividing portion 313j, the bottom surface 16a,
and the diaphragm 4a), is provided with the wall 13b. As compared with the first acoustic space
A1 (two-dot chain line) which is a space formed by the wall 13b, the bottom surface 16a, and the
diaphragm 4a, it is considered that the substantial volume contributing to the resonance is
smaller. Similarly, a second acoustic space a2, which is a space constituted by the second recess
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317 and the diaphragm 4a (a space constituted by the wall 13c, the dividing portion 313j, the
bottom surface 17a and the diaphragm 4a), is a wall As compared with the second acoustic space
A2 (two-dot chain line) which is a space formed by the wall portions 13b and 13c, the bottom
surface 17a, and the diaphragm 4a because the portion 13b is not provided, a substantial volume
contributing to resonance Is considered to be smaller. The cover portion 313 is an example of
the “diaphragm fixing portion” in the present invention.
[0065]
Then, the sound pressure (dB) of the portable gas detectors of Examples 2-1 and 2-2 was
measured using a noise meter as in the first embodiment. At this time, a predetermined sound
wave including a plurality of frequencies was generated from the buzzer 4 (diaphragm 4 a) of the
portable gas detector. Then, the frequency at which the maximum sound pressure was obtained
(maximum frequency) and the sound pressure at the time when the maximum frequency was
obtained were measured. And the difference of the sound pressure of Example 2-2 and the sound
pressure of Example 2-1 was calculated.
[0066]
The measurement results of the second embodiment are shown in FIG. From the measurement
results of the second embodiment, as in the embodiment 2-1, a person senses the maximum
frequency by providing the wall portion 13b and enlarging the volumes of the first acoustic
space A1 and the second acoustic space A2. It has been confirmed that it is possible to approach
3 kHz, which is an easy predetermined frequency. On the other hand, it has been found that the
sound pressure does not depend so much on the presence or absence of the wall 13b. As a result,
it turned out that the portable gas detector 100 of Example 2-1 which provided the wall part 13b
can enlarge both the sound pressure in a maximum frequency and the maximum frequency, and
is preferable.
[0067]
Third Example Next, in the third example, the change in sound pressure caused by the hole
portion 14a of the double-sided tape 14 of the portable gas detector 100 of the above
embodiment was measured.
[0068]
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Specifically, as Example 3-1, the same portable gas detector 100 as the above embodiment was
used as in Example 1-1.
That is, as shown in FIG. 6, the portable gas detector 100 in which the diameter R3 of the hole
portion 14a formed in the region corresponding to the third concave portion 18 of the doublesided tape 14 is 17 mm.
[0069]
Moreover, the portable gas detector in which the hole part is not formed in the area | region
corresponding to the 3rd recessed part 18 of the double-sided tape 14 was used as Example 3-2.
[0070]
Moreover, the portable gas detector whose diameter R3 of the hole 14a of the double-sided tape
14 is 20 mm was used as Example 3-3.
That is, a portable gas detector was used in which the diameter of the hole 14a was larger than
that of Example 3-1.
[0071]
Moreover, the portable gas detector whose diameter R3 of the hole 14a of the double-sided tape
14 is 10 mm was used as Example 3-4. That is, a portable gas detector was used in which the
diameter of the hole 14a was smaller than that of Example 3-1.
[0072]
And sound pressure (dB) was measured using the noise meter with the portable type gas detector
of Examples 3-1 to 3-4 similarly to the said 1st Example. At this time, with the sound level meter
when generating two alarm sounds of AL1 and AL2 from the buzzer 4 (diaphragm 4a) of the
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portable gas detector as a sound wave of a fixed frequency of 2.92 kHz (about 3 kHz). Sound
pressure (dB) was measured. And the difference of the sound pressure of Example 3-2 to 3-4 and
the sound pressure of Example 3-1 was computed in each of AL1 and AL2.
[0073]
The measurement results of the third embodiment are shown in FIG. From the measurement
results of the third embodiment, AL1 and AL2 are obtained by setting the diameter R3 of the hole
14a formed in the region corresponding to the third recess 18 of the double-sided tape 14 to 17
mm as in Example 3-1. In any of the above, a sufficient sound pressure of about 85 dB was
obtained. On the other hand, in Example 3-2 in which the hole portion was not provided, the
sound pressure was only increased to about 80 dB in any of AL1 and AL2. Thereby, it was
confirmed that the sound pressure can be increased by removing the double-sided tape 14 in the
region corresponding to the third recess 18. When the diameter of the hole 14a is larger than
that of Example 3-1 as in Example 3-3, and the diameter of the hole 14a is larger than that of
Example 3-1 as in Example 3-4. The sound pressure did not increase by more than 83 dB in any
of the smaller cases. From this, as in the case of the portable gas detector 100 of Example 3-1,
the sound pressure can be increased by providing the hole 14a having the same size as the area
corresponding to the third recess 18 of the double-sided tape 14 It turned out that it could be
made larger.
[0074]
Fourth Example Next, in the fourth example, the sound pressure and the maximum frequency
due to the size of the inner diameter R1 of the internal sound emission hole 13d of the cover
portion 13 of the portable gas detector 100 of the above embodiment The change was measured.
[0075]
Specifically, as Example 4-1, the same portable gas detector 100 as the above embodiment was
used as in Example 1-1.
That is, as shown in FIG. 6, the portable gas detector 100 in which the inner diameter R1 of the
internal sound emission hole 13d of the cover portion 13 is 2 mm was used.
04-05-2019
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[0076]
Moreover, as Example 4-2, the portable gas detector whose internal diameter R1 of the internal
sound emission hole 13d of the cover part 13 is 1 mm was used. That is, a portable gas detector
was used in which the diameter of the hole 14a was smaller than in Example 4-1.
[0077]
Moreover, as Example 4-3, the portable gas detector whose internal diameter R1 of the internal
sound emission hole 13d of the cover part 13 is 7 mm was used. That is, a portable gas detector
was used in which the diameter of the hole portion 14a was larger than that of Example 4-1.
[0078]
And sound pressure (dB) was measured using the noise meter with the portable gas detector of
Examples 4-1 to 4-3 similarly to the said 1st Example. At this time, a predetermined sound wave
including a plurality of frequencies was generated from the buzzer 4 (diaphragm 4 a) of the
portable gas detector. Then, the frequency at which the maximum sound pressure was obtained
(maximum frequency) and the sound pressure at the time when the maximum frequency was
obtained were measured. And the difference of the sound pressure of Example 4-2 and 4-3 and
the sound pressure of Example 4-1 was calculated.
[0079]
The measurement results of the fourth embodiment are shown in FIG. From the measurement
results of the fourth embodiment, by setting the inner diameter R1 of the inner sound emitting
hole 13d of the cover portion 13 to 2 mm as in the embodiment 4-1, a frequency of 3 kHz that is
a predetermined frequency that is easy for human to sense At (the maximum frequency), a
sufficient sound pressure of about 85 dB was obtained. On the other hand, when the inner
diameter R1 of the internal sound release hole 13d is smaller (1 mm) than in Example 4-1 as in
Example 4-2, the maximum frequency is increased (3.2 kHz), Sound pressure decreased by 5.4
dB. Further, when the inner diameter R1 of the inner sound emitting hole 13d is made larger (7
mm) than in Example 4-1 as in Example 4-3, there is not much decrease in sound pressure (1.2
04-05-2019
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dB) But the maximum frequency has become smaller (2.82 kHz). From these results, as in the
portable gas detector 100 of Example 4-1, the inner diameter R1 of the inner sound emission
hole 13d of the cover 13 is equal to that of the portable gas detector 100 of Example 4-1 in
order to obtain a large sound pressure It turned out that about 2 mm is preferable.
[0080]
It should be understood that the embodiments and examples disclosed herein are illustrative and
non-restrictive in every respect. The scope of the present invention is indicated not by the
description of the embodiments and examples described above but by the claims, and further
includes all modifications (variations) within the meaning and scope equivalent to the claims.
[0081]
For example, although the example in which the entire outer peripheral edge of the diaphragm
4a is fixed to the entire periphery of the circumferential step portion 113c of the cover portion
13 has been described in the above embodiment, the present invention is not limited thereto. In
the present invention, not the outer peripheral edge of the diaphragm, but the node of the
diaphragm (a position where displacement does not occur so much during vibration) may be
fixed to the cover portion. It is considered that this makes it possible to easily increase the sound
pressure of a specific frequency. Alternatively, only a part of the outer peripheral edge of the
diaphragm may be fixed to the cover without fixing the entire outer peripheral edge of the
diaphragm to the cover.
[0082]
Moreover, although the example which inclined the bottom face 17a of the 2nd recessed part 17
was shown in the said embodiment, this invention is not limited to this. In the present invention,
the bottom surface of the second recess may not be inclined.
[0083]
Moreover, although the example which used the double-sided tape 14 in order to affix the panel
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part 15 on the cover part 13 was shown in the said embodiment, this invention is not limited to
this. In the present invention, the panel portion may be attached to the cover portion by an
attachment method such as an adhesive or mechanical engagement without using a double-sided
tape. At this time, in the case where the portable gas detector is provided with a dustproof /
waterproof function, it is preferable to seal the cover and the gap between the housing and the
panel.
[0084]
Moreover, although the example which provided hole part 14a-14d in the double-sided tape 14
was shown in the said embodiment, this invention is not limited to this. In the present invention,
it is not necessary to provide a hole in the double-sided tape. In the region corresponding to the
third concave portion of the cover portion, it is preferable to provide a hole in the double-sided
tape because the sound pressure can be increased.
[0085]
Moreover, in addition to fixing the diaphragm 4a to the cover part 13 in the said embodiment,
although the example which attaches the display screen part 6 was shown, this invention is not
limited to this. In the present invention, a member for attaching the display screen portion may
be provided separately from the cover portion for fixing the diaphragm.
[0086]
Further, in the above embodiment, an internal sound emission hole 13 d connecting the first
recess 16 and the third recess 18 substantially in the center of the bottom surface 16 a of the
first recess 16 and in the approximate center of the bottom surface 18 a of the third recess 18.
Although the example which provided one is shown, this invention is not limited to this. In the
present invention, the internal sound emission hole may be provided at a position other than the
approximate center of the bottom surface of the first recess, or may be provided at a position
other than the approximate center of the bottom surface of the third recess. Also, a plurality of
internal sound emission holes may be provided to connect the first recess and the third recess.
[0087]
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DESCRIPTION OF SYMBOLS 1 Gas detection part 4a Diaphragm 6 Display screen part 13, 113,
313 Cover part (diaphragm fixed part) 13d Internal sound emission hole 15 Panel part 16, 316
1st recessed part 17, 317 2nd recessed part 18, 218 3rd recessed part 100, 100a, 100b
Portable gas detectors A1, a1 first acoustic space A2, a2 second acoustic space A3 third acoustic
space
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