JP2005303931A - Hands-free interphone device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hands-free interphone device comprising a living room master unit structured to hardly incur howling even in the case of small-sized one and to facilitate thinning. <P>SOLUTION: A speaker 2 is disposed from a position approximately corresponding to 1/10 of a lower side close to a lower end of the front face of a case 1 to a position approximately corresponding to 2/5 of the lower side close to the center in a view from the entire case 1, and a microphone 3 is disposed at a position approximately corresponding to 1/10 of an upper side close to an upper end to a position approximately corresponding to 1/6 of the upper side in a view from the entire case 1. A speech button 4 is then disposed approximately on the center of the case 1, and formed into a laterally long rectangle having an approximate 1/5 height of the height of the case 1 and an approximate 2/3 width of the width of the case 1. Furthermore, a plurality of function buttons 5a-5c are disposed from positions corresponding to 1/20 of an upper side close to the upper end to positions corresponding to 2/5 of the upper side close to the center in the view from the entire case 1. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hands-free intercom apparatus capable of making a call with a visitor without using a handset, and more particularly to a hands-free intercom apparatus capable of downsizing a living room base unit.

  Conventionally, hands-free intercom devices that can talk to visitors without using a handset have been widely used. For example, Patent Literature 1 or Patent Literature 2 has a layout as shown in Patent Literature 1 or Patent Literature 2, and the hands-free interphone device described in Patent Literature 1 is used as a master device for the hands-free intercom device. Are arranged in the order of monitor, speaker, and call button that project visitors from above. In addition, the living room master disclosed in Patent Document 2 has a display unit (monitor) at the top, a call button at the bottom, and a speaker installed at the bottom of the housing.

JP 2003-209626 A JP 2001-16339 A

However, in the case of downsizing the room base unit of the hands-free intercom device, the room base unit shown in Patent Document 1 includes a call button at the lower part of the housing, so that both the microphone and the speaker are located above the housing. It was forced to install from the center to the center, and the distance between the microphone and the speaker was shortened naturally, and howling was easy to occur. In order to reduce costs, a switch that operates by operating the call button is mounted on a circuit board on which other elements are assembled. However, since the call button is located below the speaker, the circuit board is enclosed by the thickness of the speaker. It could not be close to the front of the body, and it was placed close to the back of the case. Therefore, a large space is generated between the call button and the switch, and a transmission member is indispensable for mounting, which has been an obstacle to cost reduction.
Furthermore, for convenience of the size and layout of the call button, for example, when it has an additional function such as an unlock button, the operation button is arranged above the speaker. For this reason, the circuit board needs to have a size ranging from the call button to the function button, and a circuit board having a size covering almost the entire case is mounted, resulting in a large board and an obstacle to cost reduction.

  On the other hand, the living room master unit disclosed in Patent Document 2 can be arranged with the call button and operation buttons for additional functions close to each other, so that the circuit board can be reduced in size. Because it is suitable, it is not possible to reduce the thickness of the parent unit, and it is inevitable that the sound quality will deteriorate.

  Therefore, in view of such problems, the present invention provides a hands-free intercom apparatus having a structure in which howling is difficult to occur even if the layout of a call button, a speaker, etc. is reduced, and howling is difficult even if the size is reduced. For the purpose. It is another object of the present invention to provide a hands-free intercom device capable of suppressing howling even when a howling is likely to occur due to a resident's response operation due to downsizing.

In order to solve the above-mentioned problem, the invention according to claim 1 calls for a room base unit installed in the dwelling unit from the door unit installed in the entrance, and the door unit and the room base unit are connected. This is a hands-free intercom device that makes calls between each other, and the parent unit starts a call with a microphone for sending voice to the entrance unit and a speaker for reporting the ringing tone and voice from the entrance unit. The call button is arranged at the center of the housing of the parent unit, and the speaker and the microphone are arranged vertically apart from the call button toward the front of the housing. And
With this configuration, one of the speaker and the microphone is arranged at the lower part of the casing and the other is arranged at the upper part of the casing via the call button, so that it is possible to secure both distances in the casing, thereby preventing howling. There is an effect, and the miniaturization of the room master becomes easy. Moreover, since all are arrange | positioned in the housing | casing front surface, a housing | casing can be made thin.

The invention of claim 2 has a function button for additional functions such as unlocking of an electric lock in the invention of claim 1, and the function button is arranged at a position away from the speaker with the call button interposed therebetween. It is characterized by that.
With this configuration, since the speaker is not in the vicinity of the function button and the call button, the circuit board can be disposed in the vicinity of the front surface of the housing of the room parent device, and the housing can be further thinned.

According to a third aspect of the present invention, in the second aspect of the invention, a plurality of switches that are driven by pressing the call button and the function button are mounted on one circuit board, and the call button and the function button are A pressing piece for pressing and driving the switch is provided.
With this configuration, even if the switch is mounted on the circuit board, the call button or the function button and the switch can be coupled by merely providing a pressing piece on the button without using a separate transmission member, and the component cost can be reduced. Further, if the call button and the function button are arranged close to each other, the circuit board can be made smaller, and the component cost can be further reduced.

According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the center of the speaker is located below the lower third position of the living room main unit housing, and the microphone is The center is disposed above the upper two-fifths of the room base unit, and the call button is disposed to include the center of the room base unit housing.
With this configuration, the speaker and the microphone can be reliably separated, which is effective in preventing howling, and the design balance of the room master unit is also preferable.

According to a fifth aspect of the present invention, in any of the first to fourth aspects of the present invention, the living room base unit includes a speaker amplifier for amplifying the sound from the entrance unit, and the call button is pressed. Sometimes, a mute circuit for muting the speaker amplifier for a predetermined time is provided.
With this configuration, since the speaker amplifier is muted for a certain time after the call button is pressed, even when the front of the speaker or the microphone front is covered with the hand when operating the call button for answering the call, the speaker amplifier is released. The loudspeaker amplifier can be turned off or set to a small output, and howling does not occur even if a call button is placed in the center.

According to a sixth aspect of the present invention, in any one of the first to fourth aspects of the present invention, the living room base unit includes a speaker amplifier for amplifying the sound from the entrance unit, and the call button is pressed. In this case, an amplification factor adjustment circuit for gradually increasing the amplification factor of the speaker amplifier from zero is provided.
With this configuration, since the speaker amplifier rises slowly after the call button is pressed, howling does not occur during the call button operation to answer a call until the hand is released from the front of the speaker or the front of the microphone. can do.

A seventh aspect of the invention is characterized in that, in any of the first to sixth aspects of the invention, the room master unit includes an echo canceller circuit that prevents howling.
With this configuration, even when the front of the speaker or the front of the microphone is covered with a hand when the call button or the function button is operated, the echo canceller circuit removes the echo, so that occurrence of howling can be prevented.

The invention according to claim 8 is characterized in that, in any one of the inventions according to claims 1 to 7, the living room master unit includes a notch filter for attenuating only a preset howling frequency.
With this configuration, when the call button or function button is operated, the notch filter attenuates only the howling frequency even if the front of the speaker or the front of the microphone is covered with the hand, so that the howling signal is attenuated and howling can be prevented. it can.

According to a ninth aspect of the present invention, in any of the first to eighth aspects of the present invention, the living room base unit includes a call switching unit for automatically switching between transmission and reception and performs an automatic alternate call operation, and a microphone. A frequency discriminating unit that detects energy for each frequency of the output signal is provided, and even if a signal of a level above a certain level is input to the microphone, when the frequency discriminating unit detects an energy bias at a specific frequency, the call switching unit The switching operation is not performed, and unexpected switching of transmission / reception is prevented.
With this configuration, even if an automatic alternate call function is provided in the room master unit, the frequency discriminating unit determines howling and the resident's voice, so that the automatic alternate call function is activated by the howling and the transmitting side and the receiving side are switched. Therefore, unnecessary switching operation of the call switching unit can be prevented.
Here, the automatic alternate call is to increase the amplification of the amplifier on the side where the audio signal is large and reduce the amplification of the amplifier on the side where the audio signal is small to 0 or 0 during the call between the entrance and the base unit. This is a known technique for realizing natural conversation while preventing howling by switching the amplification level of the amplifier depending on the magnitude of the audio signal.

The invention of claim 10 is characterized in that, in the invention of claim 9, the frequency discriminating unit detects only a bias of energy of a specific frequency set in advance.
With this configuration, the frequency discriminating unit can be configured at a low price.

According to an eleventh aspect of the present invention, in any of the first to tenth aspects of the present invention, the living room base unit includes a call switching unit for automatically switching between transmission and reception and performs an automatic alternate call operation. Provided with a delay circuit that delays the operation of the switching unit, even if a signal of a certain level or more is input to the microphone, the call switching unit keeps the output signal of the microphone constant after a predetermined time after the delay circuit operates The switching operation is performed at the above level, and unexpected switching of transmission / reception is prevented.
With this configuration, in a short time howling that occurs when a button is operated, the automatic alternate call is not switched by the delay operation of the delay circuit, and an unnecessary switching operation of the call switching unit can be prevented.

According to a twelfth aspect of the present invention, in the eleventh aspect of the present invention, the room master unit includes a setting switch for setting a delay time of the delay circuit.
With this configuration, since the delay time can be set by the setting switch, the delay time can be set according to the user's preference.

  According to the hands-free intercom device of the present invention, by arranging the call button in the center of the device and arranging the microphone and the speaker via the call button, the distance between the microphone and the speaker can be secured without difficulty, and howling Effective in prevention. In addition, by arranging the function buttons in the vicinity of the call button, it is possible to reduce the size of the circuit board assembled with the switch that operates by button operation, and since the speaker is not in the vicinity of the function button and the call button, It can be placed near the front of the housing of the living room master unit, and the housing can be made thin.

Furthermore, even if a resident reaches out to the call button in order to respond to a visitor, and howling is likely to occur, the mute circuit, an amplification factor adjustment circuit that gradually increases the amplification degree of the speaker amplifier, and an echo canceller circuit By incorporating a notch filter or the like, it is possible to prevent howling from occurring when a button is operated, and it is possible to prevent howling even if a call button is arranged in the center.
In addition, when the automatic alternate call function is provided, by providing the frequency discriminating unit and the call switching unit, it is possible to prevent the automatic alternate call from being arbitrarily switched by howling, and to delay the operation timing of the call switching unit. By providing the circuit, it is possible to prevent the automatic alternate call from being switched due to howling at the time of button operation.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, embodiments of the invention will be described in detail with reference to the drawings.
FIG. 1: shows the example of embodiment of the hands-free intercom apparatus based on this invention, and has shown the front view of the living room main | base station which is the principal part of invention. In FIG. 1, 1 is a room base unit housing (hereinafter simply referred to as a housing), 2 is a call from an unillustrated entrance handset, that is, a ringing tone for notifying a call from a visitor, A speaker that outputs a voice of a visitor for the resident to establish a call with the visitor, 3 is a microphone for transmitting a voice for the resident to establish a call with the visitor, 4 Is a call button operated by a resident to respond to a call from a visitor, 5 (5a to 5c) is a function button for operating an additional function, 5a is an indoor call button for making an indoor call, 5b is An unlock button 5c for unlocking the front door is a call button for calling another household in a two-family house or the like for making a call with a parent unit in another household.

The layout of each member of the room master unit shown in FIG. 1 will be described in detail. The speaker 2 is close to the center from approximately one-tenth of the lower side close to the lower end of the front surface of the housing 1 when viewed from the entire housing 1. The speaker 2 is disposed at approximately the lower half position, and the center point of the speaker 2 is approximately at the lower quarter position of the casing 1. The microphone 3 is disposed from approximately one-tenth of the upper side near the upper end to approximately one-sixth of the upper side when viewed from the entirety of the casing 1, and the center point of the microphone 3 is generally approximately eight above the casing 1. It is in the position of a minute.
In addition, the call button 4 is disposed in the approximate center of the casing 1 and has a height that is approximately one fifth of the height of the casing 1 and a width that is approximately two thirds of the width of the casing 1. It is formed in a horizontally long rectangular shape. The center point of the call button substantially coincides with the center point of the casing. Further, the plurality of function buttons 5a to 5c are respectively arranged from the upper 1/20 close to the upper end to the upper 2/5 close to the center as viewed from the whole casing 1.
In this embodiment, the center of the speaker 2 is the position of the lower quarter of the casing 1 and the center of the microphone 3 is the position of the upper eighth of the casing 1, but the center of the speaker 2 is If it is below the lower third of the casing 1 and the center of the microphone 3 is above the upper two fifth of the casing 1, the speaker 2 and the microphone 3 are connected via the call button 4. It can be placed at a distance, which is effective in preventing howling, and is preferable from the standpoint of the design balance of the parent unit.

  2A and 2B are side explanatory views of the master unit shown in FIG. 1. FIG. 2A shows a state where no button operation is performed, and FIG. 2B shows a state where the call button 4 is operated. Moreover, the state of an internal switch or a circuit board is shown with a broken line, 10 shows the resident's hand to operate. In FIG. 2A, reference numeral 7 denotes a circuit board, and a plurality of switches 8, 8,... Corresponding to the buttons 4, 5 are mounted on the circuit board 7. Further, on the back surface of the call button 4 and the function buttons 5a to 5c, a pressing piece 9 having a total length of about 2 mm for operating the switch 8 is provided, and the thickness T of the housing 1 is about 25 mm. Then, as shown in FIG. 2 (b), when the resident presses the button (in this case, the call button 4), the pressing operation of the button is transmitted to the switch 8, and the room master unit performs the operation according to the button operation. Do.

In this way, the call button is placed in the center, the speaker is placed at the bottom of the housing, and the microphone is placed at the top of the housing, so both distances within the housing can be secured and effective in preventing howling This makes it easier to reduce the size of the parent unit. In addition, since the speaker is not in the vicinity of the function button and the call button, the circuit board can be arranged near the surface of the casing of the room base unit, the casing can be made thin, and the function button and the call button can be arranged. If they are arranged close to each other, even if a switch is mounted on the circuit board, the circuit board can be made smaller, and the component cost can be reduced.
Furthermore, it is possible to operate the switch with a button simply by providing a pressing piece without using a separate transmission member, and it is possible to reduce the cost of components and to achieve a low cost.
In this embodiment, the speaker 2 is arranged on the lower side of the casing and the microphone 3 is arranged on the upper side of the casing. However, it goes without saying that the same effect can be obtained even if the positions of the speaker 2 and the microphone 3 are reversed. Nor.

FIG. 3 shows a circuit block diagram of the room master unit of FIG. 1, wherein 11 is an interface (hereinafter abbreviated as I / F) connected to the entrance slave unit via the transmission line L1, and 12 is an audio signal amplified by the microphone 3. A microphone amplifier 13, a speaker amplifier 13 for amplifying an audio signal from the entrance cordless handset, 14 a mute circuit, and 15 a master CPU. The same components as those in FIG. 1 are given the same reference numerals, and the function buttons 5 a to 5 c are abbreviated as one function button 5.
This circuit operates as follows. Receiving the call signal from the entrance slave unit via the I / F 11, the master unit CPU 15 sounds a ring tone from the speaker 2 to notify the resident that the call has been received from the entrance slave unit. When the resident presses the call button 4 of the room master unit in response to the notification, the base unit CPU 15 forms a call path with the entrance unit and activates the speaker amplifier 13, the mute circuit 14, and the microphone amplifier 12. And
The activated mute circuit 14 operates to reduce the output from the speaker 2 for a predetermined time after the call button 4 is pressed. After the mute circuit 14 is activated, the mute circuit 14 is activated. The sound emitted from the speaker 2 is reduced for a certain time until the hand no longer covers the speaker 2. Then, after the lapse of a certain time, the operation of the mute circuit 14 is stopped, and then the speaker 2 outputs the sound from the entrance unit at a normal volume.

  Thus, when the resident presses the call button 4, the hand covers the front surface of the speaker 2 as shown in FIG. 2 (b), and the sound reported from the speaker 2 is easy to go around the microphone 3, enabling howling. However, it does not generate howling because it is a small sound even if it is not output from the speaker or is output for a certain period of time when the hand is held in front of the parent unit.

FIG. 4 shows another circuit configuration of the living room master shown in FIG. 3 differs from FIG. 3 in that an amplification factor adjustment circuit 17 is provided for gradually increasing the amplification factor of the speaker amplifier 13 (gradually increasing from 0) instead of the mute circuit 14. In addition, the same code | symbol is provided to the component same as FIG.
This circuit operates as follows. Receiving the call signal from the entrance slave unit via the I / F 11, the master unit CPU 15 sounds a ring tone from the speaker 2 to notify the resident that the call has been received from the entrance slave unit. When the resident presses the call button 4 of the room base unit in response to the notification, the base unit CPU 15 forms a communication path with the entrance handset, and the speaker amplifier 13, the amplification factor adjustment circuit 17, and the microphone amplifier 12 are connected. Active. The amplification factor adjustment circuit 17 is a circuit that gradually increases the volume from zero to a constant value over a predetermined period of time until the hand that presses the call button 4 does not cover the speaker 2 when activated. In the meantime, the amplification degree of the speaker amplifier 13 is gradually increased from zero. Then, after a predetermined time has elapsed, the amplification factor adjustment circuit 17 ends the operation with the amplification degree of the speaker amplifier 13 as a steady value, and the speaker 2 outputs the sound from the entrance cordless handset at a normal volume.
Thus, since the sound coming out of the speaker gradually increases from zero after the call button is pressed, the speaker sound is small while the hand is covering the speaker, and howling can be prevented.

FIG. 5 shows still another circuit configuration of the room master shown in FIG. 3 differs from FIG. 3 in that an echo canceller circuit 18 for canceling the sound output from the speaker amplifier 13 and circulated to the microphone amplifier 12 is provided instead of the mute circuit 14. In addition, the same code | symbol is provided to the component same as FIG.
This circuit operates as follows. Receiving the call signal from the entrance slave unit via the I / F 11, the master unit CPU 15 sounds a ring tone from the speaker 2 to notify the resident that the call has been received from the entrance slave unit. When the resident presses the call button 4 of the room base unit, the base unit CPU 15 forms a communication path with the entrance unit, and activates the speaker amplifier 13, the microphone amplifier 12, and the echo canceller circuit 18.

Thereby, even if the sound output from the speaker 2 goes around the microphone 3 and is amplified by the microphone amplifier 12 because the front surface of the speaker 2 is covered with a hand, the echo around the echo canceller circuit 18 is canceled. To do. In addition, since the echo canceller circuit 18 is in an active state during the operation of the parent room, even if other function buttons are operated, the same action is performed and the wraparound sound is canceled.
In this way, the echo canceller circuit removes echoes even if the hand is held over the room master unit, so that howling can be prevented.

FIG. 6 shows still another circuit configuration of the room master shown in FIG. 3 differs from FIG. 3 in that a notch filter 19 for attenuating only a preset howling frequency among signals output from the microphone amplifier 12 is provided instead of the mute circuit 14. In addition, the same code | symbol is provided to the component same as FIG.
This circuit operates as follows. Receiving the call signal from the entrance slave unit via the I / F 11, the master unit CPU 15 sounds a ring tone from the speaker 2 to notify the resident that the call has been received from the entrance slave unit. When the resident presses the call button 4 of the room base unit, the base unit CPU 15 forms a communication path with the entrance unit and activates the speaker amplifier 13, the microphone amplifier 12, and the notch filter 19.

Since the frequency at which howling occurs is generally determined by the shape of the casing, the frequency at which howling can be identified in advance at the stage of device development. Therefore, the notch filter 19 for attenuating only a signal of a specific frequency can be set in advance so as to attenuate only the howling frequency, and can be incorporated in the room master. Therefore, it is possible to attenuate only the howling frequency without adjusting the frequency of the notch filter 19 on site.
Therefore, by operating the notch filter 19, even if the sound output from the speaker 2 wraps around the microphone 3 and is amplified by the microphone amplifier 12 because the front surface of the speaker 2 is covered with a hand, the notch filter 19. Attenuate only the sound of a specific frequency among the sounds that wrap around.
In this way, even if the hand is held over the living room master unit, the notch filter attenuates only the howling frequency, so that the howling signal is attenuated and howling can be prevented.

  FIG. 7 shows still another circuit configuration of the room master shown in FIG. In place of the mute circuit 14 shown in FIG. 3, a call switching unit 21 for automatically switching between transmission and reception is provided, and the room base unit has an automatic alternate call function and detects a specific frequency energy. The difference is that 20 is provided. In addition, the same code | symbol is provided to the component same as FIG.

  This circuit operates as follows. Receiving the call signal from the entrance slave unit via the I / F 11, the master unit CPU 15 sounds a ring tone from the speaker 2 to notify the resident that the call has been received from the entrance slave unit. When the resident presses the call button 4 of the room base unit, the base unit CPU 15 forms a communication path with the entrance unit, and the speaker amplifier 13, the microphone amplifier 12, the call switching unit 21, the frequency discriminating unit 20, Is active.

In the embodiment shown in FIG. 7, since the room master has an automatic alternate call function, it is not necessary to operate the call button 4 when responding. However, the resident who is talking is switched from the automatic alternate call to the forced call. In such a case, the call button 4 is operated. Alternatively, when an additional function such as an electric lock is operated, the function button 5 is operated. In this case, the front surface of the speaker 2 is covered with a hand, the sound output from the speaker 2 wraps around the microphone 3, the sound signal circulated by the microphone amplifier 12 is amplified, and the energy of a specific frequency increases and howling. However, the call switching unit 21 and the frequency discriminating unit 20 operate as follows to prevent unnecessary operation of the call switching unit 21 due to howling.
The frequency discriminating unit 20 that receives a signal from the microphone amplifier 12 detects this change, that is, a change in which only the energy of a specific frequency is increased, and transmits it to the call switching unit 21. The call switching unit 21 is informed that the specific frequency has an energy bias from the frequency discriminating unit 20, so that the increased signal is not determined as the voice of the resident and does not switch between transmission and reception. .

In this way, even if an automatic alternate call function is provided in the living room master unit, the frequency discriminating unit judges howling and the resident's voice, so that the automatic alternate call function operates by howling, and the transmitting side and the receiving side are switched. Therefore, unnecessary switching operation of the call switching unit can be prevented.
Since the howling frequency can be specified in advance as in the embodiment of FIG. 6, the frequency discriminating unit 20 is configured to detect energy of only a specific frequency. The unit 20 can have a simple circuit configuration. However, since the howling frequency specified in advance is not limited to one, it is more effective to discriminate a plurality of frequencies.

  FIG. 8 shows still another circuit configuration of the room master shown in FIG. In place of the mute circuit 14 shown in FIG. 3, the call switching unit 21 is provided instead of the mute circuit 14 and an automatic alternate call function is provided. And the delay circuit 23 which delays the operation | movement of the telephone call switching part 21 for 0.1 to 1 second, and the setting switch 24 which sets the delay time of the delay circuit 23 manually are provided. In addition, the same code | symbol is provided to the component same as FIG.

  This circuit operates as follows. Receiving the call signal from the entrance slave unit via the I / F 11, the master unit CPU 15 sounds a ring tone from the speaker 2 to notify the resident that the call has been received from the entrance slave unit. Upon receiving the notification, when the resident presses the call button 4 of the room base unit, the base unit CPU 15 forms a communication path with the entrance unit, and activates the speaker amplifier 13, the microphone amplifier 12, and the call switching unit 21. And

In the embodiment of FIG. 8, as in the case of FIG. 7, the living room base unit has an automatic alternate call function, so that it is not necessary to operate the call button 4 when responding. When switching from an alternate call to a forced call, the call button 4 is operated. Alternatively, when an additional function such as an electric lock is operated, the function button 5 is operated. In this case, the front surface of the speaker 2 is covered with a hand, and the sound output from the speaker 2 wraps around the microphone 3, and the sound signal circulated by the microphone amplifier 12 is amplified, and howling may occur due to the wraparound. However, the call switching unit 21 and the delay circuit 23 operate as follows to prevent unnecessary switching of the call switching unit 21.
When a howling or voice signal is generated, the call switching unit 21 detects the howling or voice signal, and the call switching unit 21 that has detected the howling or voice signal operates the delay circuit 23. The operation of the delay circuit 23 waits for a set delay time, and the call switching unit 21 performs the howling detection operation again. At this time, if the call switching unit 21 detects the signal again, the call switching unit 21 recognizes that the signal is a voice signal, and switches between the transmitting side and the receiving side of the automatic alternating call. Conversely, if no howling is detected at the end of the delay time, the call switching unit 21 does not perform the switching operation.

  As a result, in short-time howling that occurs when a button is operated, the automatic alternate call is not switched by the delay operation of the delay circuit, and an unnecessary switching operation of the call switching unit can be prevented. In addition, because there are individual differences in how to press the buttons, if the delay time is too long, smooth switching may not be performed and the call may be jerky. To prevent this, the resident operates the setting switch. Thus, by changing the delay time, it is possible to switch between the transmitting side and the receiving side of the automatic alternate call without any sense of incongruity.

The mute circuit 14, the amplification factor adjustment circuit 17, the echo canceller circuit 18, the notch filter 19, the frequency discriminating unit 20, the delay circuit, etc. are individually provided to take countermeasures against howling. May be. In particular, by providing the automatic alternate call function shown in FIGS. 7 and 8 together with the mute circuit 14 and the amplification factor adjustment circuit 17, stable call switching can be performed, and howling can be suppressed well.
In the above embodiment, since the speaker 2 is arranged under the call button 4, the countermeasure when the speaker 2 is covered with the hand has been described. However, the speaker in which the microphone 3 is arranged under the call button 4 is described. In the configuration in which the positions of the microphone 2 and the microphone 3 are reversed, the microphone 3 is covered with a hand when the call button 4 is operated. Also in this case, howling is likely to occur, but howling can be suppressed by the above circuit, and malfunction can be prevented in the case of an apparatus having an automatic alternate call function.

1 shows a first embodiment of a hands-free intercom device according to the present invention, and is a front view of a living room parent device that is a main part of the invention. FIG. It is a right cross-section explanatory drawing of the living room main | base station of FIG. FIG. 2 is a circuit block diagram of the living room master device of FIG. 1. It is a circuit block diagram which shows the other circuit structure of the living room main | base station of FIG. It is a circuit block diagram which shows the further another circuit structure of the living room main | base station of FIG. It is a circuit block diagram which shows the further another circuit structure of the living room main | base station of FIG. It is a circuit block diagram which shows the further another circuit structure of the living room main | base station of FIG. It is a circuit block diagram which shows the further another circuit structure of the living room main | base station of FIG.

Explanation of symbols

  1 ·· Home room housing 2 ·· Speaker 3 · Mic 4 ·· Call button 5 ·· Function button 7 ·· Circuit board 8 ·· Switch 9 ·· Pressing piece 12 ···・ Mic amplifier, 13 ・ ・ Speaker amplifier, 14 ・ ・ Mute circuit, 15 ・ ・ Master CPU, 17 ・ ・ Amplification factor adjustment circuit, 18 ・ ・ Echo canceller circuit, 19 ・ ・ Notch filter circuit, 20 ・ ・ Frequency discrimination , 21 .. Call switching unit, 23 .. Delay circuit, 24 .. Setting switch.

Claims (12)

A hands-free intercom device in which a call is made from an entrance cordless handset installed at a front door to a living room base phone installed in a dwelling unit, and a call is made between the entrance cordless handset and the living room base phone,
The living room base unit includes a microphone for sending voice to the entrance unit, a speaker for reporting a ringing tone and voice from the entrance unit, and a call button for starting a call,
The call button is arranged in a substantially central part of the casing of the living room main unit, and the speaker and the microphone are arranged apart from each other up and down toward the front of the casing with the call button as a center. Hands-free intercom device. 2. A hands-free device according to claim 1, further comprising a function button for an additional function such as unlocking of an electric lock, the function button being disposed at a position away from the speaker with the call button interposed therebetween. Intercom device. A plurality of switches that are driven by pressing the call button and the function button are mounted on a single circuit board, and the call button and the function button include a pressing piece that presses and drives the switch. The hands-free intercom apparatus according to claim 2, wherein: The center of the speaker is positioned below the lower third position of the living room base unit housing, and the microphone is positioned at the center of the upper second half of the living room base unit. The hands-free intercom apparatus according to any one of claims 1 to 3, wherein the hands-free intercom apparatus is arranged above and the call button is arranged so as to include a center of the base unit housing. The living room base unit includes a speaker amplifier for amplifying sound from the entrance unit, and a mute circuit for muting the speaker amplifier for a predetermined time when the call button is pressed. The hands-free intercom apparatus according to any one of claims 1 to 4. The living room master unit includes a speaker amplifier for amplifying sound from the entrance cordless handset, and an amplification factor adjustment circuit that gradually increases the amplification factor of the speaker amplifier from zero when the call button is pressed. The hands-free intercom apparatus according to any one of claims 1 to 4, further comprising a hands-free intercom apparatus. The hands-free intercom apparatus according to any one of claims 1 to 6, wherein the living room master unit includes an echo canceller circuit that prevents occurrence of howling. The hands-free intercom apparatus according to any one of claims 1 to 7, wherein the living room base unit includes a notch filter that attenuates only a preset howling frequency. The living room master unit is equipped with a call switching unit for automatically switching between transmission and reception and performs an automatic alternating call operation, and also includes a frequency discriminating unit that detects energy for each frequency of the microphone output signal,
Even when a signal of a certain level or more is input to the microphone, when the frequency discriminating unit detects a bias of energy at a specific frequency, the call switching unit does not perform a switching operation, and the transmission / reception is not expected. The hands-free intercom apparatus according to any one of claims 1 to 8, wherein switching is prevented. The hands-free intercom apparatus according to claim 9, wherein the frequency discriminating unit detects only an energy bias of a specific frequency set in advance. The living room base unit includes a call switching unit for automatically switching between transmission and reception, and performs an automatic alternating call operation, and includes a delay circuit that delays the operation of the call switching unit,
Even if a signal of a certain level or more is input to the microphone, the call switching unit performs a switching operation when the output signal of the microphone is continuously at a certain level or more after a predetermined time during which the delay circuit operates. The hands-free intercom apparatus according to any one of claims 1 to 10, wherein unexpected switching of transmission / reception is prevented. The hands-free intercom apparatus according to claim 11, wherein the living room base unit includes a setting switch for setting a delay time of the delay circuit.

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