JP2009273038A - Door intercom slave unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a door intercom slave unit that suppresses attenuation of a voice by a film of water. <P>SOLUTION: On an internal surface of a sound through-hole 41p for input bored on the front side of a microphone MC in a housing 4, a thickness varying means 41s is provided which makes the inner shape on the rear side larger than that on the front side. On an inner peripheral surface of the sound hole 41p for input, the front-rear size of a lower end surface within a range of a downward direction is smaller than the front-rear size of an upper end surface within a range of an upward direction. The thickness varying means 41s makes the thickness of the film WD of water at an upper end portion smaller than that at a lower end portion, so attenuation of a voice by the film WD of water is suppressed as compared with a case wherein the front-rear size of the lower end portion of the downward internal surface of the sound hole 41p for input is made equal to the front-rear size of the upper end portion of the upward internal surface of the sound hole 41p for input without providing the thickness varying means 41s. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a door phone slave used in a door phone system.

  2. Description of the Related Art Conventionally, in a door phone system, a door phone slave unit used for a call with a door phone parent device installed indoors has been provided. In general, the door phone sub-unit is fixed to a construction surface such as a vertical wall surface or a sign pole outdoors.

  In this type of doorphone handset, an input sound for allowing the sound input to the microphone to pass through is provided on the front surface of the housing (that is, the surface opposite to the surface directed to the construction surface) in which the microphone and speaker for communication are stored. A hole and an output sound hole for allowing sound output from the speaker to pass therethrough are provided (see, for example, Patent Document 1).

  Here, since the microphone is generally smaller than the speaker, the input sound hole is narrower than the output sound hole. For this reason, the input sound hole is likely to be blocked by a film of water such as raindrops. When the input sound hole is blocked with a water film, the sound input to the microphone is attenuated in the water film, which may cause a trouble in the call.

Therefore, conventionally, a housing has been provided with a water suction groove that communicates with the input sound hole and absorbs water by capillary action (see, for example, Patent Document 1). According to this configuration, formation of a water film is suppressed.
JP 2007-143079 A

  However, when the amount of water entering the sound hole for input exceeds the amount of water that can be absorbed, such as when the amount of precipitation is high, the above-mentioned water ditch has stopped functioning.

  The present invention has been made in view of the above reasons, and an object thereof is to provide a door phone sub-unit in which attenuation of sound in a water film is suppressed.

  The invention of claim 1 includes a microphone and a housing that accommodates the microphone and is fixed to an outdoor construction surface, and an input that allows sound input to the microphone to pass through the front portion of the microphone in the housing. Thickness that makes the front and rear dimensions of the lower end face of the downward range smaller than the front and rear dimensions of the upper end face of the upward range The present invention is characterized in that a height changing unit is provided.

  According to this invention, even if a water film is formed to block the input sound hole, the surface tension of the water acts on the inner surface of the input sound hole provided with the thickness changing portion, thereby Since the thickness of the film is thinner at the upper end than at the lower end, the thickness change portion is not provided, and the front and rear dimensions of the lower end of the range facing downward on the inner surface of the input sound hole are the upper end of the range facing upward Compared with the case where the dimensions are equal to those before and after, attenuation of sound in the water film is suppressed.

  The invention of claim 2 is characterized in that, in the invention of claim 1, the rear end of the lower end surface in the range facing downward on the inner surface of the input sound hole is located in front of the front end of the microphone.

  According to the present invention, compared to the case where the rear end of the lower end surface in the range facing downward on the inner surface of the input sound hole is set behind the front end of the microphone, the upper end portion of the water film that closes the input sound hole Is difficult to reach the microphone.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the thickness changing portion has a right end surface area in a range that is rightward on the inner surface of the input sound hole and a leftward surface on the inner surface of the input sound hole It is the shape which makes the area of the left end surface of a certain range differ mutually.

  According to this invention, the attenuation of the sound in the water film is suppressed as compared with the case where the areas of the left end surface in the range facing left on the inner surface of the input sound hole coincide with each other.

  According to the first aspect of the present invention, the thickness changing portion is formed on the inner surface of the input sound hole so that the front and rear dimensions of the lower end surface of the downward range are smaller than the front and rear dimensions of the upper end surface of the upward range. Therefore, even if a film of water that closes the input sound hole is formed, the surface tension of the water acts on the inner surface of the input sound hole provided with the thickness changing portion. Since the thickness of the water film is thinner at the upper end than at the lower end, the thickness changer is not provided, and the front and rear dimensions of the lower end surface of the input sound hole on the inner surface of the input sound hole are above the upper range. Compared with the case where the dimensions of the front and rear of the end face are the same, the sound attenuation in the water film is suppressed.

  According to the second aspect of the present invention, the rear end of the lower end surface in the range facing downward on the inner surface of the input sound hole is located on the front side of the front end of the microphone. Compared to the case where the rear end of the lower end surface in a certain range is located behind the front end of the microphone, the upper end portion of the water film blocking the input sound hole is less likely to reach the microphone.

  According to the invention of claim 3, the thickness changing portion includes an area of the right end surface in the range facing right on the inner surface of the input sound hole, and an area of the left end surface in the range facing left on the inner surface of the input sound hole. Therefore, the attenuation of the sound in the water film is suppressed as compared with the case where the areas of the left end faces in the range facing left on the inner surface of the input sound hole are made to coincide with each other.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  As shown in FIGS. 2 to 4, the doorphone slave device 1 according to the present embodiment includes a communication unit 11 that transmits and receives electrical signals to and from the doorphone master unit HS via a signal line Ls, and a visitor calls a resident. A communication unit 11 and a signal line for transmitting an image signal, which is an electrical signal indicating an image captured by the camera 14a, having a camera 14a. An imaging unit 14 that transmits to the intercom base phone HS via Ls, and a light source unit 15 that includes four infrared light emitting diodes 15a serving as a light source for the imaging unit 14 to perform imaging at night or the like.

  Specifically, the communication unit 11 includes, for example, a known impedance matching circuit that matches impedance with the signal line Ls, and the call unit 13, the imaging unit 14, and the light source unit 15 are respectively connected via the communication unit 11. It is controlled by the intercom master unit HS.

  The calling unit 12 outputs a predetermined calling signal to the intercom main unit HS via the communication unit 11 and the signal line Ls when the calling button 12a is pressed by a visitor and when the calling button 12a is pressed. It consists of a call signal generation circuit (not shown).

  The call unit 13 converts a voice into an audio signal, which is an electrical signal, and outputs it to the doorphone master unit HS via the communication unit 11 and the signal line Ls, and the signal line Ls and the communication unit from the doorphone master unit HS. 11 and a speaker SP for converting an audio signal input via the audio signal 11 into audio. The speaker SP is disposed on the disc-shaped cone SP1 with the thickness direction in the front-rear direction (vertical direction in FIG. 3) and the rear side of the cone SP1 (lower side in FIG. 3), and vibrates the cone SP1 according to the audio signal. And a speaker body SP2 that generates sound by the operation.

  The camera 14a of the imaging unit 14 includes a lens and an imaging element (not shown) that converts an image input from the front through the lens into an electrical signal. As the image sensor, a CCD (Charge Coupled Device) type or a CMOS type can be used. In addition, the imaging unit 14 generates an image signal by performing known processing such as modulation on the electrical signal output from the camera 14a, and outputs the image signal to the intercom base unit HS via the communication unit 11 and the signal line Ls. An image signal generation circuit (not shown).

  Here, the doorphone slave unit of the present embodiment is controlled by the doorphone master unit HS when a fire sensor is detected when the fire sensor is connected to the doorphone master unit HS, for example. An alarm operation for issuing an alarm by voice from the speaker SP of the unit 13 is performed. The light source unit 15 includes, for example, an alarming light emitting diode 15b whose light color is red and blinking when the alarming operation is performed, the already described infrared light emitting diode 15a for illumination, and the door phone master HS. And a single light source driving circuit (not shown) for driving the infrared light emitting diode 15a and the alarm light emitting diode 15b, respectively.

  The communication unit 11, the calling unit 12, the calling unit 13, the imaging unit 14, and the light source unit 15 as described above can be realized by well-known techniques, and thus detailed illustration and description thereof are omitted.

  The circuit parts of the communication unit 11, the calling unit 12, the imaging unit 14, and the light source unit 15, and the circuit components other than the microphone MC and the speaker SP of the communication unit 13 are mounted on the printed wiring board 20 and are circuit blocks. 2 is constituted. A circular speaker insertion hole 20a through which the speaker body SP2 is inserted is provided in the printed wiring board 20 in the thickness direction.

  Moreover, the door phone sub unit 1 of this embodiment includes a terminal block 3 in which four screw terminals 31 are mounted on a terminal board 30 smaller than the printed wiring board 20 of the circuit block 2. Each screw terminal 31 of the terminal block 3 is connected to the communication unit 11 via an electric wire (not shown), for example.

  Furthermore, the door phone sub unit 1 of the present embodiment includes a housing 4 that houses and holds the microphone MC and the speaker SP, the circuit block 2, and the terminal block 3 that the call unit 13 has. As shown in FIGS. 5A and 5B, the housing 4 has a rectangular parallelepiped shape as a whole. Hereinafter, the vertical and horizontal directions are based on FIG. 5A, and the vertical direction in FIG. That is, the printed wiring board 20 has the surface on which the call button 12a, the camera 14a, and the light source unit 15 are mounted facing forward, and the terminal board 30 has the surface on which the screw terminal 31 is mounted facing backward. The up, down, left, and right directions correspond to the up, down, left, and right directions toward the construction surface in a state where the door phone child device 1 of the present embodiment is fixed to the construction surface in the correct orientation.

  The housing 4 includes a rectangular parallelepiped body 41 having an open rear surface, and a cover 42 that is mechanically coupled to the body 41 so as to fit into the opening on the rear surface of the body 41 and closes the opening on the rear surface of the body 41. Each of the body 41 and the cover 42 is made of a synthetic resin molded product, for example. Here, two engagement holes 41a are provided in the lower wall of the body 41 so as to be arranged side by side in the vertical direction, and two engagement holes are provided at positions corresponding to the engagement holes 41a at the lower end portion of the cover 42. The nail | claw 42a is arranged in the left and right and protrudes below. Further, the cover 42 is provided with three screw insertion holes 42b (only two are shown) penetrating in the front-rear direction (upper and lower in FIG. 3), and on the rear surface (inner bottom surface) of the body 41 as shown in FIG. At positions corresponding to the screw insertion holes 42b, cylindrical screwing portions 41b each having a screw hole opened on the rear surface are projected rearward. Then, each engagement claw 42a is engaged with the engagement hole 41a, and screwed with three coupling screws SC1 (only two are shown) that are respectively inserted into the screw insertion holes 42b and screwed into the screwing portions 41b. Thus, the cover 42 is mechanically coupled to the body 41.

  In addition, the doorphone sub unit 1 of the present embodiment is fixed to a construction surface (not shown) such as an outdoor wall surface and is fixed to the construction surface using a mounting base 5 that holds the housing 4. The mounting base 5 has a flat rectangular parallelepiped shape whose front surface is opened as a whole. Further, the inner peripheral surface of the mounting base 5 is provided with a step 50 that makes the inner shape of the front side larger than the inner shape of the rear side. The mounting table 5 is brought into contact with the front surface of the step 50. Further, an engagement hole 51 is vertically penetrated in the upper wall of the mounting base 5, and a screwing portion 52 having a screw hole opened on the front surface is penetrated in the front and rear at the lower end portion of the mounting base 5. Yes. In addition, a screw insertion hole 41c through which a mounting screw SC2 screwed to the screwing portion 52 of the mounting base 5 is inserted is provided in the lower end portion of the body 41 in the front-rear direction. A notch 42c that is open to the lower side and the lower side to avoid the mounting screw SC2 is provided. Further, the upper surface of the body 41 (that is, the upper surface of the housing 4) is provided with an engaging convex portion 41d. The housing 4 is engaged with the engaging convex portion 41d into the engaging hole 51 and the mounting screw SC2. It is fixed to the mounting base 5 by screwing.

  Here, the screw insertion hole 41c opens into a screw recess 41e provided at the lower end of the front surface of the body 41, and the head of the mounting screw SC2 is accommodated in the screw recess 41e. Furthermore, in order to improve the appearance, a screw door 43 that covers the attachment screw SC2 as viewed from the front is attached to the body 41. The screw door 43 is made of, for example, a synthetic resin molded product, and is flat and has a square-shaped main body portion 43a as viewed from the thickness direction, and projects from the one surface of the main body portion 43a in the thickness direction of the main body portion 43a. Two leg portions 43b, and columnar engagement convex portions 43c projecting in a direction away from the other leg portion 43b at the tip of each leg portion 43b. In addition, an engagement hole 41f is provided in each of the inner surfaces facing the left and right sides of the screw recess 41e, and each of the engagement protrusions 43c engages with the engagement hole 41f, whereby the screw door 43 is Between the closed position that covers the mounting screw SC2 when viewed from the front and the open position that exposes the mounting screw SC2 when viewed from the front, it is pivotally attached to the body 41 in a plane viewed from the left-right direction. Yes. In the closed position, the surface of the main body 43a of the screw door 43 opposite to the surface on which the leg portions 43b project is substantially flush with the front surface of the body 41.

  A square-shaped exposure hole 53 that exposes a part of the rear surface of the housing 4 when viewed from the rear is provided at the center of the bottom surface of the mounting base 5. Further, on the upper side of the exposure hole 53, there is provided a screw insertion notch 54 having a lower end communicating with the exposure hole 53 and opened on both the front and rear sides, and below the exposure hole 53 and above the screwing portion 52. The screw insertion hole 55 having a long oval shape on the right and left is provided through the front and rear, and the mounting base 5 is inserted into a screw (not shown) inserted into the screw insertion notch 54 and the screw insertion hole 55. By fixing with a screw (not shown), the rear surface is fixed to the construction surface with the rear surface facing the construction surface. In addition, two drain holes 56 for discharging water that has entered between the mounting base 5 and the construction surface are arranged vertically at the lower end portion of the mounting base 5 so as to be vertically arranged.

  Further, at the left end portion of the cover 42, four terminal exposure holes 42d for exposing the screw terminals 31 of the terminal block 3 one by one are vertically arranged in the front-rear direction. Further, partition protrusions 42e projecting forward from the periphery of the opening on the front side of the terminal exposure hole 42d so as to surround the screw terminals 31 and insulate the screw terminals 31 from the rear. Here, the signal line Ls is a two-wire type, and two of the four screw terminals 31 of the terminal block 3 are connected to the intercom base unit HS via the signal line Ls. That is, the communication unit 11 is connected to the signal line Ls via the screw terminal 31. Further, another device (not shown) can be connected to the remaining two screw terminals 31, and the other device connected to the remaining two screw terminals 31 is a door phone. Connected to the intercom master unit HS via the device 1 and the signal line Ls. Further, a dip switch (not shown) is mounted on the rear surface of the printed wiring board 20 of the circuit block 2 to switch between connecting and terminating another device for the remaining two screw terminals 31. A switch exposure hole 42f that exposes the dip switch is provided in the center of the cover 42 so that the dip switch can be switched through the switch exposure hole 42f. Furthermore, a switch lid 44 made of, for example, a synthetic resin molded product and closing the switch exposure hole 42f is attached to the cover 42 by fitting into a recess (not shown) provided on the rear surface of the cover 42, for example.

  Further, on the front side of the calling button 12a in the body 41, a push button handle 45 made of, for example, a synthetic resin molded product and transmitting the pressing force from the front to the calling button 12a is held, and the body 41 is called from the front as viewed from the front. A square button insertion hole 41g for exposing the button 12a is provided through the front and rear. The push button handle 45 includes a rectangular parallelepiped main body portion 45a inserted into the button insertion hole 41g, and a flange portion 45b that protrudes from the rear end portion of the outer peripheral surface of the main body portion 45a and is located on the rear side of the body 41. The arm portion 45c protrudes upward from the left and right end portions of the upper end surface of the flange portion 45b. Further, on the rear surface of the body 41, on the upper side of the button insertion hole 41g, two pivotal convex portions 41h facing left and right are respectively projected rearward. Each arm portion 45c is provided with a shaft convex portion 45d projecting inward in the left-right direction, and each pivot support convex portion 41h has a shaft convex portion 45d inserted on the outward surface in the left-right direction. A hole (not shown) is opened, and each shaft projection 45d is inserted into the bearing hole, so that the push button handle 45 can be rotated to displace the main body 45a back and forth with respect to the body 41. It is pivotally attached to. Further, at the left end of the flange portion 45b, a spring portion 45e that is flat in the front-rear direction and that has a rear surface facing the front surface of the left arm portion 45c with a gap therebetween projects upward. The upper end of the spring part 45e is in elastic contact with the rear surface of the body 41, and the spring force of the spring part 45e becomes the restoring force of the main body part 45a. That is, when the main body 45a receives a pressing force from the front in the push button handle 45, the push button handle 45 rotates against the body 41 against the spring force of the spring 45e, and the call button 12a is moved by the rear surface of the main body 45a. Is pressed. Thereafter, when the pressing force to the main body 45a is released, the push button handle 45 is returned by the spring force of the spring 45e.

  Further, a camera window hole 41i is provided in the body 41 at the upper left end portion (upper right end portion in FIG. 6) which is the front side of the camera 14a, and the body 41 is made of a material having translucency. A camera window 46 that closes the camera window hole 41i is fixed by a known means such as ultrasonic welding.

  Further, a light source window hole 41j is provided in the body 41 at the upper right end portion (the upper left end portion in FIG. 6) which is the front side of the light source portion 15 in the front and rear directions. A light source window 47 for closing the light source window hole 41j is fixed by a known means such as ultrasonic welding. Each of the camera window body 46 and the light source window body 47 may have a function of an appropriate optical filter such as a polarization filter or a wavelength filter. Such a camera window body 46 and a light source window body 47 can be realized by a well-known technique, and a detailed description thereof will be omitted.

  The speaker SP is disposed below the camera 14a. A circular speaker insertion hole 20a through which the speaker body SP2 is inserted penetrates the front and rear of the printed wiring board 20 of the circuit block 2 below the camera 14a. In the cover 42, a speaker support convex portion 42g with which the rear end of the speaker body SP2 abuts is provided on the rear side of the speaker insertion hole 20a. Further, a plurality (eight in the figure) of output sound holes 41k through which sounds output from the speakers SP are passed through the front side of the speakers SP in the body 41 are provided in the front-rear direction. Between the opening on the rear side of the output sound hole 41k and the speaker SP, a waterproof sheet 61 made of, for example, a synthetic resin film and preventing water from entering from the output sound hole 41k is interposed. The waterproof sheet 61 is formed as a thin film so as to pass sound output from the speaker SP. In addition, on the rear surface of the body 41, two pedestal convex portions 41m that are semicircular arc shapes and that generally form an annular shape that surrounds each output sound hole 41k and that respectively contact the front surface of the cone SP1 are formed on the left and right sides. The projections are rearwardly arranged side by side and are semicircular arcs concentric with the pedestal convex portions 41m, respectively, and form an annular shape surrounding each pedestal convex portion 41m and the cone SP1 when viewed from the rear, and are formed on the outer peripheral surface of the cone SP1. Two positioning projections 41n that are positioned in contact with each other are arranged to protrude rearward side by side.

  Further, the microphone MC is disposed on the upper right side of the light source unit 15, and in the body 41, on the upper right side of the light source window hole 41j (upper left side in FIG. 6), a cylindrical microphone holding cylinder into which the front end portion of the microphone MC is inserted. 41o protrudes backward. In addition, an input sound hole 41p for allowing sound input to the microphone MC to pass therethrough is formed in the front and rear in a portion surrounded by the microphone holding cylinder 41o when viewed from the rear in the body 41. Between the opening on the rear side of the input sound hole 41p and the microphone MC, a waterproof sheet 62 made of, for example, a synthetic resin film and preventing water from entering from the input sound hole 41p is interposed. The waterproof sheet 62 is formed as a thin film so as to pass sound input to the microphone MC.

  Further, the engagement hole 41 a at the lower end of the body 41 is not closed by the cover 42, and a gap is formed between the engagement claw 42 a of the cover 42 and the inner surface of the engagement hole 41 a of the body 41. Then, the water that has entered the housing 3 is discharged through the gap.

  In addition, there is a gap between the lower end portions of the two pedestal convex portions 41m and between the lower end portions of the two positioning convex portions 41n so that the output sound hole 41k communicates with the engagement hole 41a serving as a drain hole. Is formed. That is, when water enters the space between the speaker SP and the body 41 from the output sound hole 41k or the like, the water is separated into the gap between the lower ends of the two base convex portions 41m and the two It is discharged to the lower side of the space through the gap between the lower end portions of the positioning convex portion 41n, and further discharged out of the housing 4 through the engagement hole 41a. Further, a drainage groove 41r is provided on the rear surface of the body 41 from directly below the drainage opening as viewed from the rear to directly above the engagement hole 41a. The drainage groove 41r allows drainage to the engagement hole 41a. Promptly.

  Here, as shown in FIGS. 1A and 7, a thickness changing step 41s is provided on the inner surface of the input sound hole 41p so that the inner shape of the rear side is larger than that of the front side. Due to the thickness changing step 41s, an inverted U-shaped recess extending from the upper end to the left and right sides is formed at the rear end of the inner peripheral surface of the input sound hole 41p. On the peripheral surface, the dimension before and after the lower end surface in the downward range (that is, the thickness of the portion constituting the lower end surface in the body 41) d1 is the dimension before and after the upper end surface in the upward range (that is, the body). 41, the thickness constituting the upper end surface is smaller than d2. That is, the thickness changing step 41s is a thickness changing unit in the claims.

  Hereinafter, the effect of this embodiment will be described. When the input sound hole 41p is closed with the water film WD as shown in FIG. 1B, the thickness of the water film WD (front and rear dimensions, that is, the left and right dimensions in FIG. 1B). Is affected by the shape of the inner peripheral surface of the input sound hole 41p due to the surface tension. In the present embodiment, due to the thickness changing step 41s, the dimension d1 of the input sound hole 41p before and after the lower end of the downward inner surface (left and right in FIGS. 1 (a) and 1 (b)) is equal to the input sound hole 41p. Since it is smaller than the dimension d2 before and after the upper end portion of the upward inner surface, the thickness of the water film WD is thinner at the upper end portion than at the lower end portion. Thus, when the thickness changing step 41s is not provided and the front and rear dimensions of the lower inner surface of the input sound hole 41p are made equal to the front and rear dimensions of the upper inner surface of the input sound hole 41p. In comparison, since the thickness of the upper end portion of the water film WD is reduced, attenuation of sound in the water film WD is suppressed.

  By the way, when the entire water film WD is in contact with the microphone MC, the sound is more easily attenuated by the water film WD than when a gap (bubble) is present between the water film WD and the microphone MC. . However, in the present embodiment, the rear end of the lower end surface in the range facing downward on the inner surface of the input sound hole 41p is positioned in front of the front end of the microphone MC by the thickness changing step 41s. Compared with the case where the rear end of the lower end surface of the range facing downward on the inner surface of the sound hole 41p is located behind the front end of the microphone MC, the upper end portion of the water film WD that closes the input sound hole 41p becomes the microphone MC. Hard to reach.

  As shown in FIG. 8, the upper and lower positions of the lower end of the thickness changing step 41s as the thickness changing portion may be made different between the left and right of the front opening of the input sound hole 41p. In the example of FIG. 8, the upper and lower positions of the lower end of the thickness changing step 41s are on the left side (lower right side in FIG. 8) and above the right side (upper left side in FIG. 8) (upper right side in FIG. 8). ). If this configuration is adopted, the area of the right end surface in the range facing right on the inner surface of the input sound hole 41p is made smaller than the area of the left end surface in the range facing left on the inner surface of the input sound hole 41p. Therefore, compared with the case where the area of the right end surface is the same as the area of the left end surface, the thickness of the upper end portion of the water film WD becomes thinner, so that the attenuation of sound in the water film WD is suppressed.

(A) (b) shows embodiment of this invention, respectively (a) is sectional drawing which shows the principal part, (b) is explanatory drawing which shows an effect. It is a block diagram which shows schematic structure same as the above. It is a disassembled perspective view which shows the same as the above. It is sectional drawing which shows the same as the above. The same as above, (a) is a front view, (b) is a bottom view. It is a rear view which shows a body same as the above. It is a perspective view which shows the principal part of a body same as the above. It is a perspective view which shows the principal part of the body of the example of a change same as the above.

Explanation of symbols

1 Door phone slave unit 4 Housing 41p Sound hole for input 41s Thickness change stage HS Door phone master unit MC Microphone

Claims (3)

A microphone and a housing that houses the microphone and is fixed to an outdoor construction surface;
In the front part of the microphone in the housing, an input sound hole that allows sound input to the microphone to pass therethrough is provided through the front and rear.
The inner surface of the input sound hole is provided with a thickness changing portion that makes the front and rear dimensions of the lower end surface of the downward range smaller than the front and rear dimensions of the upper end surface of the upward range. A doorphone child unit.   2. A door phone child device according to claim 1, wherein the rear end of the lower end surface of the range facing downward on the inner surface of the input sound hole is located in front of the front end of the microphone.   The thickness changing portion has a shape in which the area of the right end surface in the range facing right on the inner surface of the input sound hole is different from the area of the left end surface in the range facing left on the inner surface of the input sound hole. The door phone sub-unit according to claim 1 or 2, wherein

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