JP6401531B2 - Portable gas detector - Google Patents

Description

  The present invention relates to a portable gas detector, and more particularly to a portable gas detector including a diaphragm that generates sound waves.

  2. Description of the Related Art Conventionally, a portable gas detector including a diaphragm that generates sound waves is known (see, for example, Patent Document 1).

  Patent Document 1 discloses a portable gas detector including a warning buzzer including a piezoelectric vibrator (diaphragm) that generates sound waves and a case. In the case of the alarm buzzer of the portable gas detector described in Patent Document 1, a 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. Yes. As a result, one acoustic space is formed by the piezoelectric vibrator and the case on the sound emission side of the piezoelectric vibrator in the alarm buzzer.

JP2013-125601A

  However, in the portable gas detector described in Patent Document 1, since only one acoustic space is formed by the piezoelectric vibrator and the case in the alarm buzzer, the acoustic space is generated by the piezoelectric vibrator. It is considered that it is not possible to sufficiently resonate at a predetermined frequency that is easily perceived by humans among the frequencies of the generated sound waves. As a result, it is considered that there is a problem that it is difficult to output a sound wave having a predetermined frequency to the outside of the portable gas detector with a sufficient sound pressure.

  The present invention has been made to solve the above-described problems, and one object of the present invention is a portable gas capable of outputting a sound wave having a predetermined frequency to the outside with a sufficient sound pressure. It is to provide a detector.

  A portable gas detector according to one aspect of the present invention includes a gas detection unit that detects a detection target gas, and a vibration plate that vibrates and generates a sound wave when reporting gas detection by the gas detection unit. The portable gas detector includes a circular first recess and an annular second recess formed so as to surround the first recess, and vibrates so as to cover the first recess and the second recess. When the plate is fixed, 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.

  In the portable gas detector according to one aspect of the present invention, as described above, the diaphragm is fixed so as to cover the first concave portion and the second concave portion, so that the first acoustic space corresponding to the first concave portion and A diaphragm fixing portion is provided in which a second acoustic space corresponding to the second recess is formed. Accordingly, by providing not only the first acoustic space but also the second acoustic space, the sound wave generated by the diaphragm can be sufficiently resonated at a predetermined frequency at which a person can easily sense, so that a sound wave having a predetermined frequency can be obtained. Can be output to the outside of the portable gas detector with sufficient sound pressure. This effect has been confirmed by sound pressure measurement (example) described later.

  In the portable gas detector according to the above aspect, preferably, the diaphragm fixing portion includes a third concave portion, a third concave portion, and a first concave portion formed on a surface opposite to the surface on which the first concave portion is formed. And an internal sound emitting hole connecting the recess. If comprised in this way, since it can suppress that the sound wave output from the 1st recessed part via the internal sound emission hole is attenuate | damped by a 3rd recessed part, the predetermined | prescribed frequency which a person is easy to detect reliably 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 on a member different from the diaphragm fixing portion, Since 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 parts can be suppressed. In addition, since the portable gas detector is mainly carried by the user, downsizing is particularly desired, and from this point, it is particularly required to suppress the upsizing.

  In this case, it is preferable that the surface of the diaphragm fixing portion on the side opposite to the surface on which the first recess is formed be pasted on a region other than the region corresponding to the third recess, A panel portion that covers the concave portion so as not to be exposed on the outer surface is further provided, and the panel portion is attached to the diaphragm fixing portion so as to cover the third concave portion, whereby the diaphragm fixing portion corresponds to the third concave portion. Three acoustic spaces are formed. If comprised in this way, it can fully suppress that the sound wave output to the 3rd recessed part from the 1st recessed part via the internal sound emission hole by the 3rd acoustic space attenuates in the 3rd recessed part. A sound wave having a predetermined frequency can be output to the outside of the portable gas detector with sufficient sound pressure more reliably. Thereby, even if the sound emitting hole is not provided in the panel portion covering the third recess, the sound wave having a predetermined frequency can be output to the outside of the portable gas detector with sufficient sound pressure. Further, the panel portion can suppress the internal sound emitting hole and the third recess from being exposed to the outer surface, so that foreign matter such as moisture and dust that has entered from the internal sound emitting hole is prevented from adhering to the diaphragm. Can be suppressed. Thereby, the frequency of the sound wave generated from the diaphragm can be prevented from deviating from a predetermined frequency that is easy for humans to sense, and the sound pressure of the sound wave can be reduced.

  The portable gas detector according to the above aspect preferably further includes a display screen unit, and the display screen unit is attached to the diaphragm fixing unit in addition to the diaphragm being fixed. If comprised in this way, since the diaphragm fixing | fixed part can be used also for attachment of a display screen part other than fixation of a diaphragm, the components for attachment of a display screen part are unnecessary. Thereby, it can suppress that a number of parts increases.

  According to the present invention, as described above, a sound wave having a predetermined frequency can be output to the outside of the portable gas detector with a sufficient sound pressure.

It is the perspective view which showed the whole structure of the portable gas detector by one Embodiment of this invention. It is the block diagram which showed the control structure of the portable gas detector by one Embodiment of this invention. It is the perspective view which showed the use condition of the portable gas detector by one Embodiment of this invention. It is the disassembled perspective view which looked at the portable gas detector by one Embodiment of this invention from the front. It is the disassembled perspective view which looked at the cover part, diaphragm, and display screen part of the portable gas detector by one Embodiment of this invention from back. FIG. 4 is a cross-sectional view taken along line 400-400 in FIG. 1. It is the fragmentary sectional view which showed the internal structure of the portable gas detector of Example 1-2 of Example 1 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 the comparative example 1 of 1st 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 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.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the drawings.

  First, with reference to FIGS. 1-3, the whole structure of the portable gas detector 100 by one Embodiment of this invention is demonstrated.

  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 gas leakage or the like by outputting an alarm when detecting the detection target gas. In addition, the portable gas detector 100 has a dustproof and waterproof function, and water and dust are prevented from entering the portable gas detector 100.

  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 section 6.

  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 (combustible gas) burns. Combustion type gas sensing element is included. In addition, as a gas detection element of the gas detection part 1, it is not restricted to a contact combustion type gas detection element, You may use 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.

  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). Moreover, the control part 2 is comprised so that the warning which alert | reports that the detection object gas exceeded the predetermined density | concentration will be output from the buzzer 4, the two lamps 5, and the display screen part 6 at the time of an alarm. Specifically, at the time of alarm, the control unit 2 outputs a predetermined buzzer sound from the buzzer 4 and lights a predetermined color lamp in the lamp 5 so as to notify the user of the alarm. It is configured. The control unit 2 is configured to display predetermined information such as the concentration of the detection target gas on the display screen unit 6 at the time of alarm. When the portable gas detector 100 is calibrated, the control unit 2 displays the calibration result on the display screen unit 6 so that the user can confirm the calibration result.

  The input button 3 is provided for accepting an input operation by the user such as turning on / off the power of the portable gas detector 100 and an instruction to save the calibration result.

  As shown in FIG. 3, the portable gas detector 100 is configured so that a clip 7 for attaching to a user's belt 101, chest pocket, and helmet (not shown) can be attached. Thereby, it is comprised so that the user can carry the portable gas detector 100 easily.

  Next, a specific structure of the portable gas detector 100 will be described with reference to FIGS. 1, 2, and 4 to 6.

  As shown in FIG. 1, the portable gas detector 100 includes a main body 10, a sensor cap member 20 and a battery unit 30 that are detachably attached to the main body 10. The sensor cap member 20 is attached to a side surface on one side (X2 side) in the longitudinal direction (X direction) of the main body 10. The battery unit 30 is attached to the back surface of the main body 10 on the rear side (Y2 side) in the front-rear direction (Y direction).

  In addition, the portable gas detector 100 is formed in a substantially rectangular parallelepiped shape with the battery unit 30 mounted on the main body 10, and each corner of the rectangular parallelepiped is rounded.

  As shown in FIG. 4, the main body unit 10 includes a housing 11, a substrate unit 12 and a cover unit 13 disposed inside the housing 11, a double-sided tape 14, and a panel unit 15. . Further, the substrate unit 12 is configured to be fixed to the rear side (Y2 side) of the cover unit 13. Further, as shown in FIG. 5, a vibration plate 4 a that vibrates and generates a sound wave when notifying gas detection by the gas detection unit 1 and a display screen unit 6 are attached to the rear surface 13 a of the cover unit 13. ing. A detailed mounting structure will be described later.

  The diaphragm 4a includes 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) when a predetermined electrical signal is applied to the pair of electrodes 104a from the control unit 2 (see FIG. 2). As a result, a sound wave is generated from the diaphragm 4a when the air is vibrated based on the vibration of the diaphragm 4a. The diaphragm 4 a constitutes a part of the buzzer 4.

  The display screen unit 6 includes a pair of conductive rubbers 6a made of zebra rubber or the like attached to the rear, and a display region 6b on which an image such as predetermined information is displayed by the control unit 2 (see FIG. 2). Yes. The pair of conductive rubbers 6a are fixed to the upper side (Z1 side) and the lower side (Z2 side) of the display screen unit 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 region 6b.

  As shown in FIGS. 4 and 6, the housing 11 is formed in a box shape having an open front side (Y1 side). In addition, the substrate portion 12 and the cover portion 13 are accommodated in an accommodation portion 11 a formed inside the housing 11.

  As shown in FIG. 6, the substrate unit 12 is combined so that a plurality of substrates 12 a are stacked in the front-rear direction (Y direction), and a CPU that constitutes the control unit 2 is attached. In addition, wiring (not shown) of the diaphragm 4a (see FIG. 5) is connected to the frontmost (Y1) substrate 12a, and the display screen unit 6 is connected via a pair of conductive rubbers 6a. . As a result, the diaphragm 4a and the display screen unit 6 are each driven through the wiring and the pair of conductive rubbers 6a. Further, an insulating sheet 12b for ensuring insulation between the substrates 12a is disposed between the substrates 12a.

  The cover part 13 is comprised from transparent resin. As shown in FIGS. 4 and 5, the cover portion 13 is configured in a rectangular shape extending in the longitudinal direction (X direction) and the vertical direction (Z direction), and the side portion extends from substantially the entire outer edge portion. It is formed to extend toward the rear side (Y2 side).

  Here, in this embodiment, as shown in FIG. 5, the rear surface 13 a of the cover portion 13 has an annular wall portion 13 b and a larger diameter than the annular wall portion 13 b, and the wall portion 13 b On the other hand, an annular wall portion 13c formed concentrically is formed. Both the wall portions 13b and 13c are formed so as to protrude rearward (Y2 direction) from the rear surface 13a of the cover portion 13. As a result, the rear surface 13a of the cover portion 13 is formed on the inner side of the wall portion 13b, and is formed on the inner side of the circular first concave portion 16 and the wall portion 13c as viewed in plan from the rear, and on the wall portion 13b. An annular second concave portion 17 formed on the outer side and viewed in plan from the rear is provided.

  Further, a step 113c for fixing the diaphragm 4a is formed over the entire circumference of the wall 13c inside the outer wall 13c (on the second recess 17 side). As shown in FIG. 6, the step 113 c is formed so as to be located on the rear side of the rear side (Y2 side) end of the inner wall portion 13 b. The vibration plate 4a is bonded 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. Note that the entire outer peripheral edge of the diaphragm 4a is fixed to the entire circumference of the circumferential step 113c. Further, since the stepped portion 113c is located on the rear side with respect to the rear side end portion of the inner wall portion 13b, a gap is formed between the diaphragm 4a and the wall portion 13b.

  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 formed by the diaphragm 4a (the space formed by the walls 13b and 13c, the bottom surface 17a, and the diaphragm 4a) becomes the second acoustic space A2. Has been. The first acoustic space A1 and the second acoustic space A2 are connected to each other through a gap between the wall portion 13b and the diaphragm 4a.

  In the first acoustic space A1 and the second acoustic space A2, among the sound wave frequencies based on the vibrations generated in the diaphragm 4a, a sound wave of about 3 kHz, which is a frequency that humans can easily sense, is resonated. In particular, a sound wave of about 3 kHz is resonated in the second acoustic space A2. As a result, it is possible to output a sound pressure of a sound wave having a frequency of about 3 kHz with a sufficient magnitude from an internal sound emitting hole 13d described later. In general, the frequency that humans can easily sense is about 3 kHz or more and about 4 kHz or less.

  Further, as shown in FIG. 6, the bottom surface 16a on the front side (Y1 side) of the first recess 16 is formed in a flat surface shape. The bottom surface 17a on the front side of the second recess 17 is provided so as to incline forward from the inner wall portion 13b toward the outer wall portion 13c. At this time, in the bottom surface 17a of the second recess portion 17, the bottom surface 17a on the inner wall portion 13b side is located on the rear side (Y2 side) with respect to the bottom surface 16a of the first recess portion 16, and the bottom surface on the outer wall portion 13c side. 17 a is formed so as to be positioned on the front side of the bottom surface 16 a of the first recess 16. The bottom surface 17a is formed so as to be inclined in substantially the same direction as an inclined portion 18b of a third recess 18 described later.

  Further, an internal sound emitting hole 13d is formed in the approximate center of the bottom surface 16a of the first recess 16. The internal sound emitting hole 13d penetrates the cover portion 13 in the front-rear direction (Y direction) so as to connect the rear surface 13a and the front surface 13e of the cover portion 13. Thereby, the sound wave generated in the diaphragm 4a and resonated in the first acoustic space A1 and the second acoustic space A2 is output from the internal sound emitting hole 13d to the front surface 13e side (front side, Y1 side) of the cover portion 13. It is configured to be. The internal sound emitting hole 13d has an inner diameter R1 of about 2 mm.

  In the present embodiment, as shown in FIG. 6, a third recess 18 is formed in a region corresponding to the first recess 16 and the second recess 17 in the front surface 13 e of the cover portion 13. As shown in FIG. 4, the third recess 18 is formed in a circular shape when viewed from the front (Y1 direction). The third recess 18 is formed so as to surround the flat bottom surface 18a and the bottom surface 18a, and is inclined rearward (Y2 side) from the outer edge of the third recess 18 toward the bottom surface 18a (inside). And an inclined portion 18b. In addition, an internal sound emitting hole 13 d connected to the bottom surface 16 a of the first recess 16 is provided in the approximate center of the bottom surface 18 a of the third recess 18.

  Further, as shown in FIG. 6, the substantially circular bottom surface 16a of the first recess 16 and the substantially circular bottom surface 18a of the third recess 18 are formed so as to overlap each other when viewed from the front-rear direction (Y direction). Has been. Note that the bottom surface 16a of the first recess 16 and the bottom surface 18a of the third recess 18 are both formed in a circular shape having a diameter R2 of about 13 mm when viewed in plan. The annular outer edge of the second recess 17 and the annular outer edge of the third recess 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 portion 17 and the annular outer edge portion of the third recess portion 18 are both formed in a circular shape having a diameter R3 of about 17 mm when viewed in a plan view.

  Further, as shown in FIG. 5, a display screen attachment portion 13 f to which the display screen portion 6 is attached is formed in the vicinity of the center portion of the rear surface 13 a of the cover portion 13. The display screen attachment portion 13f is formed in a concave shape, and a window portion 113f having a thickness smaller than that of other areas of the cover portion 13 is formed at the center of the display screen attachment portion 13f. Then, the display screen section 6 is fitted into the display screen mounting section 13f, so that the display screen section 6b (see FIG. 1) of the display screen section 6 is positioned at a position corresponding to the window section 113f. 6 is configured to be attached to the cover portion 13. Here, since the thickness of the window part 113f is smaller than the thickness of the other area | region of the cover part 13, it displays on the display area 6b from the exterior of the portable gas detector 100, protecting the display area 6b by the window part 113f. It is possible to improve the visibility of the image to be displayed.

  4 and 5, the cover portion 13 is formed on the lower side (Z2 side) of the display screen mounting portion 13f, and a pair of hole portions 13g in which the detection portions 3a of the input buttons 3 are respectively disposed. And a hole 13h formed on the X2 side of the display screen mounting portion 13f and in which the detection portion 3a of the input button 3 is disposed. Moreover, the cover part 13 is formed in the X2 side upper side (Z1 side) of the display screen attachment part 13f, and the hole part 13i (refer FIG. 4) by which the light emission part 5a (refer FIG. 2) of the lamp | ramp 5 is arrange | positioned. Have.

  The panel part 15 is formed from a resin sheet having a thickness of about 0.2 mm through which sound waves can pass. Moreover, as shown in FIG. 4, the panel part 15 is formed in the rectangular shape seeing planarly from the front-back direction (Y direction). Further, as shown in FIG. 6, the panel portion 15 is provided with a double-sided tape 14 on a step portion 11 b formed in a circumferential shape at an end portion on the front side (Y1 side) of the housing 11 and a front surface 13 e of the cover portion 13. Is pasted through.

  In the present embodiment, the panel portion 15 is not formed with a hole penetrating the panel portion 15. That is, the panel part 15 is arrange | positioned so that the whole front surface 13e of the cover part 13 may be covered from the front side (Y1 side). As a result, as shown in FIG. 6, both the internal 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. Yes.

  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 inclined portion 18b, and the panel portion 15) becomes the third acoustic space A3. The vessel 100 is configured. In the third acoustic space A3, a sound wave of about 3 kHz, which is a frequency that is easy for humans to detect, is resonated among the sound wave frequencies based on the vibration generated in the diaphragm 4a. As a result, the sound pressure of the sound wave having a frequency of about 3 kHz can be output to the outside of the portable gas detector 100 through the panel unit 15 with a sufficient magnitude.

  In the portable gas detector 100 of the present embodiment, sound waves are transmitted to the outside of the portable gas detector 100 by the diaphragm 4a, the first acoustic space A1, the second acoustic space A2, and the third acoustic space A3. A buzzer 4 for outputting is configured.

  As shown in FIG. 4, the double-sided tape 14 for attaching the panel portion 15 to the cover portion 13 is formed in a rectangular shape as seen in a plan view from the front-rear direction (Y direction), like the panel portion 15. Has been. As shown in FIG. 6, a hole portion 14 a is formed in a region of the double-sided tape 14 corresponding to the third recess 18 of the cover portion 13. That is, the double-sided tape 14 is not located in the region corresponding to the third recess 18 of the cover portion 13. The hole 14a of the double-sided tape 14 is formed in a circular shape having a diameter R3 of about 17 mm when viewed in plan. That is, the hole 14 a of the double-sided tape 14 is formed in a circular shape that is substantially the same size as the third recess 18. In FIG. 6, for ease of understanding, the thickness of the double-sided tape 14 in the front-rear direction (Y direction) is exaggerated, but the actual thickness of the double-sided tape 14 is relative to the thickness of the panel portion 15. Small enough.

  Further, in the double-sided tape 14, a region corresponding to the window portion 113f of the display screen attachment portion 13f, a region corresponding to the pair of holes 13g and 13h, and a region corresponding to the pair of holes 13i are respectively provided with holes. 14b, 14c and 14d are formed.

  On the other hand, in the region other than the holes 14a to 14d of the double-sided tape 14, an adhesive (shaded portion in FIG. 4) is applied over the entire area. That is, an area corresponding to the third recess 18 of the cover part 13, an area corresponding to the window part 113f of the display screen mounting part 13f, an area corresponding to the pair of holes 13g and 13h, and an area corresponding to the pair of holes 13i. Then, while the panel part 15 is not affixed on the front surface 13e of the cover part 13, the panel part 15 is affixed on the front surface 13e of the cover part 13 in the area | region other than that. Accordingly, the front surface 13e of the cover portion 13 and the step portion 11b of the housing 11 and the panel portion 15 can be bonded together, so that the front surface 13e of the cover portion 13 and the step portion 11b of the housing 11 are It is possible to suppress water and dust from entering the inside of the housing 11 from the gap with the panel unit 15.

  The casing 11 of the main body 10 and the casings of the sensor cap member 20 and the battery unit 30 are both made of resin to which a conductive material that is an antistatic agent is added. Thereby, the danger of ignition by electrostatic charging can be avoided.

  In the present embodiment, the following effects can be obtained.

  In the present embodiment, as described above, the vibration plate 4a is fixed to the step 113c of the cover 13 so as to cover the first recess 16 and the second recess 17, so that the first sound corresponding to the first recess 16 is obtained. 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 easy for humans to detect, so the portable gas detector can detect the sound wave of the predetermined frequency with sufficient sound pressure. 100 can be output to the outside.

  Moreover, in this embodiment, by providing the 3rd recessed part 18 in the front surface 13e on the opposite side to the rear surface 13a in which the 1st recessed part 16 of the cover part 13 was formed, 13 d of internal sound-release holes are formed by the 3rd recessed part 18. Since the sound wave output from the first concave portion 16 can be suppressed from being attenuated, it is possible to reliably detect a sound wave having a predetermined frequency (about 3 kHz) that is easy for humans to detect with a sufficient sound pressure. Can be output to the outside of the device 100. 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 13 d extends by the amount not provided with another member. While being able to suppress enlargement, an increase in the number of parts can be suppressed.

  Moreover, in this embodiment, the 3rd acoustic space A3 corresponding to the 3rd recessed part 18 is formed by affixing the panel part 15 on the front surface 13e of the cover part 13 so that the 3rd recessed part 18 may be covered. Accordingly, the third acoustic space A3 can sufficiently suppress the sound wave output from the first recess 16 to the third recess 18 through the internal sound emitting hole 13d from being attenuated in the third recess 18. Thus, sound waves having a predetermined frequency can be output to the outside of the portable gas detector 100 with sufficient sound pressure. Thereby, even if the sound emission hole is not provided in the panel part 15 which covers the 3rd recessed part 18, it is made to output the sound wave of a predetermined frequency to the exterior of the portable gas detector 100 with sufficient sound pressure. Can do. Further, since the internal sound emitting hole 13d and the third recess 18 can be suppressed from being exposed to the outer surface by the panel portion 15, foreign matters such as moisture and dust that have entered from the internal sound emitting hole 13d are prevented from being vibrated by the diaphragm 4a. It can suppress adhering to. Thereby, the frequency of the sound wave generated from the diaphragm 4a can be prevented from deviating from a predetermined frequency (about 3 kHz) that is easily perceived by a person, and the sound pressure of the sound wave can be reduced.

  In the present embodiment, in addition to fixing the diaphragm 4 a to the cover portion 13, the display screen portion 6 is attached. Thereby, since the cover part 13 can be used not only for fixing the diaphragm 4a but also for attaching the display screen part 6, a part for attaching the display screen part 6 is not necessary. Thereby, it can suppress that a number of parts increases.

  Next, with reference to FIGS. 6 to 13, four types of sound pressure measurements (first to fourth examples) performed to confirm the effect of the present invention will be described.

(First embodiment)
In the first example, the change in the sound pressure when 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. It was measured.

  Specifically, as Example 1-1, the same portable gas detector 100 as that in 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.

  Moreover, as Example 1-2, as shown in FIG. 7, while having the same 1st acoustic space A1 and 2nd acoustic space A2 as the said embodiment, the inclination part 18b (two-dot chain line) of the said embodiment is provided. A portable gas detector 100 a having a third acoustic space a <b> 3 constituted by the third recess 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.

  In addition, 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 recess 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 is not formed in the cover part 213 is used.

  And the sound pressure of the sound wave from the portable gas detector of Examples 1-1 and 1-2 and the comparative example 1 was measured using the noise meter which is not illustrated. Specifically, the sound level meter was arranged so as to face the portion corresponding to the buzzer 4 of the panel unit 15 of the portable gas detector. At that time, the buzzer 4 and the sound level meter were separated by 300 mm. Thereafter, a sound wave having 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 with a sound level meter. And the difference of the sound pressure of Example 1-2 and Comparative Example 1 and the sound pressure of Example 1-1 was calculated.

  The measurement results of the first example are shown in FIG. From the measurement result of the first example, 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 has a sufficient sound of 80.8 dB. The pressure was measured. On the other hand, in Comparative Example 1 in which the second acoustic space A2 is not formed, a sound pressure of 76.6 dB, which is 4.2 dB smaller than the sound pressure of Example 1-1, was measured. This is considered to be because the sound pressure of a sound wave having a fixed frequency of 2.97 kHz did not increase sufficiently due to the absence of the second acoustic space A2. As a result, it can be confirmed 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 the first acoustic space A1. It was.

  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 smaller by 9.6 dB than the sound pressure of Example 1-1. Was measured. Thereby, it was found that the inclined portion 18b of the third acoustic space A3 has a function of suppressing the attenuation of the sound pressure of the sound wave having a fixed frequency of 2.97 kHz. 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 and is preferable. found.

(Second embodiment)
Next, in the second example, changes in the sound pressure and the maximum frequency due to the presence or absence of the wall portion 13b inside the cover portion 13 of the portable gas detector 100 of the above embodiment were measured.

  Specifically, as Example 2-1, the same portable gas detector 100 as that of 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 cover 13 was provided with the inner wall 13b was used.

  Moreover, as Example 2-2, as shown in FIG. 10, the portable gas detector 100b in which the wall part 13b (two-dot chain line) inside the cover part 313 is not provided was used. At this time, the first recessed portion 316 and the second recessed portion 317 were separated by the dividing portion 313j that does not protrude rearward (Y2 side) from the wall portion 13b. In this case, the wall portion 13b is provided in the first acoustic space a1, which is a space formed by the first recess 316 and the vibration plate 4a (a space formed by the partitioning portion 313j, the bottom surface 16a, and the vibration plate 4a). The substantial volume contributing to resonance is considered to be smaller than the first acoustic space A1 (two-dot chain line), which is a space constituted by the wall portion 13b, the bottom surface 16a, and the diaphragm 4a. Similarly, the second acoustic space a2 which is a space formed by the second recess 317 and the vibration plate 4a (a space formed by the wall portion 13c, the partition portion 313j, the bottom surface 17a, and the vibration plate 4a) is a wall portion. Compared with the second acoustic space A2 (two-dot chain line), which is a space constituted by the walls 13b and 13c, the bottom surface 17a, and the diaphragm 4a, a substantial volume contributing to resonance, as much as 13b is not provided. Is thought to be smaller. The cover portion 313 is an example of the “diaphragm fixing portion” in the present invention.

  Then, for the portable gas detectors of Examples 2-1 and 2-2, the sound pressure (dB) was measured using a sound level meter, as in the first example. At this time, a predetermined sound wave including a plurality of frequencies was generated from the buzzer 4 (diaphragm 4a) of the portable gas detector. The frequency at which the maximum sound pressure was obtained (maximum frequency) and the sound pressure 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 computed.

  The measurement results of the second example are shown in FIG. From the measurement result of the second example, as in Example 2-1, by providing the wall portion 13b and increasing the volume of the first acoustic space A1 and the second acoustic space A2, the person senses the maximum frequency. It was confirmed that it was possible to approach 3 kHz, which is an easily predetermined frequency. On the other hand, it was found that the sound pressure does not depend much on the presence or absence of the wall portion 13b. As a result, it was found that the portable gas detector 100 of Example 2-1 provided with the wall 13b can increase both the maximum frequency and the sound pressure at the maximum frequency, and is preferable.

(Third embodiment)
Next, in the third example, a change in sound pressure caused by the hole 14a of the double-sided tape 14 of the portable gas detector 100 of the above embodiment was measured.

  Specifically, as Example 3-1, the same portable gas detector 100 as in 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 14a formed in the region corresponding to the third recess 18 of the double-sided tape 14 is 17 mm was used.

  Further, as Example 3-2, a portable gas detector in which no hole was formed in a region corresponding to the third recess 18 of the double-sided tape 14 was used.

  Moreover, as Example 3-3, the portable gas detector whose diameter R3 of the hole 14a of the double-sided tape 14 is 20 mm was used. That is, the portable gas detector having a larger diameter of the hole portion 14a than that of Example 3-1 was used.

  Moreover, as Example 3-4, the portable gas detector whose diameter R3 of the hole 14a of the double-sided tape 14 is 10 mm was used. That is, the portable gas detector having a smaller diameter of the hole portion 14a than that of Example 3-1 was used.

  And with respect to the portable gas detectors of Examples 3-1 to 3-4, the sound pressure (dB) was measured using a sound level meter as in the first example. At this time, in the sound level meter when two alarm sounds of AL1 and AL2 are generated as sound waves having a fixed frequency of 2.92 kHz (about 3 kHz) from the buzzer 4 (diaphragm 4a) of the portable gas detector. Sound pressure (dB) was measured. And the difference of the sound pressure of Examples 3-2 to 3-4 and the sound pressure of Example 3-1 was calculated in each of AL1 and AL2.

  The measurement results of the third example are shown in FIG. From the measurement results of the third example, 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, AL1 and AL2 In either case, a sufficient sound pressure of about 85 dB was obtained. On the other hand, in Example 3-2 in which no hole was provided, the sound pressure increased only to about 80 dB in both AL1 and AL2. Thus, 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. Further, when the diameter of the hole 14a is made larger than that of Example 3-1, as in Example 3-3, and the diameter of the hole 14a is made larger than that of Example 3-1, as in Example 3-4. In any of the cases where it was reduced, the sound pressure did not increase beyond 83 dB. Therefore, as in the portable gas detector 100 of Example 3-1, the sound pressure is reduced by providing the hole 14a having the same size as the region corresponding to the third recess 18 of the double-sided tape 14. It turns out that it can be made larger.

(Fourth embodiment)
Next, in the fourth example, changes in sound pressure and maximum frequency due to the size of the inner diameter R1 of the internal sound emission hole 13d of the cover part 13 of the portable gas detector 100 of the above embodiment were measured.

  Specifically, as Example 4-1, the same portable gas detector 100 as in 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 sound emitting hole 13d of the cover portion 13 has an inner diameter R1 of 2 mm was used.

  Further, as Example 4-2, a portable gas detector having an inner diameter R1 of the internal sound emitting hole 13d of the cover portion 13 of 1 mm was used. That is, the portable gas detector having a smaller diameter of the hole portion 14a than that of Example 4-1 was used.

  Further, as Example 4-3, a portable gas detector in which the inner sound emitting hole 13d of the cover portion 13 has an inner diameter R1 of 7 mm was used. That is, the portable gas detector having a larger diameter of the hole portion 14a than that of Example 4-1 was used.

  And with respect to the portable gas detectors of Examples 4-1 to 4-3, the sound pressure (dB) was measured using a sound level meter as in the first example. At this time, a predetermined sound wave including a plurality of frequencies was generated from the buzzer 4 (diaphragm 4a) of the portable gas detector. The frequency at which the maximum sound pressure was obtained (maximum frequency) and the sound pressure when the maximum frequency was obtained were measured. And the difference of the sound pressure of Examples 4-2 and 4-3 and the sound pressure of Example 4-1 was computed.

  The measurement results of the fourth example are shown in FIG. From the measurement result of the fourth example, as in Example 4-1, the internal sound emitting hole 13d of the cover portion 13 has an inner diameter R1 of 2 mm, and thus a frequency of 3 kHz, which is a predetermined frequency that is easily perceived by humans. At (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 emitting hole 13d was made smaller than that of Example 4-1 as in Example 4-2 (1 mm), the maximum frequency was increased (3.2 kHz), The sound pressure was reduced by 5.4 dB. Further, when the inner diameter R1 of the internal sound emitting hole 13d was made larger than that of Example 4-1 as in Example 4-3 (7 mm), the sound pressure did not decrease much (1.2 dB). However, the maximum frequency was reduced (2.82 kHz). From these results, in order to obtain a large sound pressure at a frequency that is easily perceivable by humans, the inner diameter R1 of the internal sound emitting hole 13d of the cover portion 13 is set as in the portable gas detector 100 of Example 4-1. It has been found that about 2 mm is preferable.

  The embodiments and examples disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments and examples but by the scope of claims for patent, and includes all modifications (modifications) within the meaning and scope equivalent to the scope of claims for patent.

  For example, in the above embodiment, the example in which the entire outer peripheral edge of the diaphragm 4a is fixed to the entire circumference of the circumferential step portion 113c of the cover portion 13 is shown, but the present invention is not limited to this. In the present invention, not the outer peripheral edge of the diaphragm, but a node of the diaphragm (a position where displacement is not so much generated during vibration) may be fixed to the cover portion. Thereby, it is considered that the sound pressure of a specific frequency can be easily increased. Moreover, you may fix only a part of outer periphery of a diaphragm to a cover part, without fixing the whole outer periphery of a diaphragm to a cover part.

  Moreover, in the said embodiment, although the example which inclined the bottom face 17a of the 2nd recessed part 17 was shown, this invention is not limited to this. In the present invention, the bottom surface of the second recess need not be inclined.

  Moreover, although the example which used the double-sided tape 14 in order to affix the panel part 15 to the cover part 13 was shown in the said embodiment, this invention is not limited to this. In this invention, you may attach a panel part to a cover part by attachment methods, such as an adhesive agent and mechanical engagement, without using a double-sided tape. At this time, in the case where a dustproof and waterproof function is provided in the portable gas detector, it is preferable to seal the gap between the cover part and the casing and the panel part.

  Moreover, although the example which provided the holes 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 addition, in the area | region corresponding to the 3rd recessed part of a cover part, it is preferable to provide a hole part in a double-sided tape since a sound pressure can be enlarged.

  Moreover, although the example which attaches the display screen part 6 to the cover part 13 in addition to fixing the diaphragm 4a was shown in the said embodiment, this invention is not limited to this. In this invention, you may provide the member which attaches a display screen part separately from the cover part which fixes a diaphragm.

  Moreover, in the said embodiment, 13 d of internal sound emission holes which connect the 1st recessed part 16 and the 3rd recessed part 18 in the approximate center of the bottom face 16a of the 1st recessed part 16, and the approximate center of the bottom face 18a of the 3rd recessed part 18 are shown. Although the example which provided one is shown, this invention is not limited to this. In the present invention, the internal sound emitting 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 approximately center of the bottom surface of the third recess. In addition, a plurality of internal sound emission holes that connect the first recess and the third recess may be provided.

DESCRIPTION OF SYMBOLS 1 Gas detection part 4a Diaphragm 6 Display screen part 13, 113, 313 Cover part (diaphragm fixing | 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 detector A1, a1 1st acoustic space A2, a2 2nd acoustic space A3 Third acoustic space

Claims (4)

A gas detector for detecting the detection target gas;
A diaphragm that vibrates and generates a sound wave when notifying gas detection by the gas detector;
The diaphragm includes a circular first recess and an annular second recess formed to surround the first recess, and the diaphragm is fixed so as to cover the first recess and the second recess. Thus, a portable gas detector comprising: a diaphragm fixing portion in which a first acoustic space corresponding to the first recess and a second acoustic space corresponding to the second recess are formed.   The diaphragm fixing portion includes a third recess formed on a surface opposite to the surface on which the first recess is formed, and an internal sound emitting hole connecting the third recess and the first recess. The portable gas detector according to claim 1, further comprising: The internal sound emitting hole and the third concave portion are pasted to a region other than the region corresponding to the third concave portion of the surface of the diaphragm fixing portion opposite to the surface on which the first concave portion is formed. Further includes a panel portion that covers the outer surface so as not to be exposed.
The panel portion is attached to the diaphragm fixing portion so as to cover the third recess, whereby a third acoustic space corresponding to the third recess is formed in the diaphragm fixing portion. 2. The portable gas detector according to 2. A display screen part,
The portable gas detector according to any one of claims 1 to 3, wherein the display screen unit is attached to the diaphragm fixing unit in addition to the diaphragm being fixed.

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