JPH02260863A - Interphone set - Google Patents

Abstract

PURPOSE:To extremely reduce feeding loss inexpensively with simple circuit constitution by connecting a speaker in a master set between a power output and a speech line and supplying power to a slave set via the speaker. CONSTITUTION:A power output of a master set 31 is fed to a speech line 33 via a reception speaker 41 and to a slave set 35. The DC resistance of the speaker 41 is normally comparatively low and the AC resistance is high. Thus, no voltage loss almost takes place in the feeding circuit. Because of high AC impedance, even when the speaker 41 connects to the speech line 33, adverse effect such as attenuation of a speech signal is not caused. Thus, it is not required to use an exclusive circuit device such as a choke coil or a pseudo inductance circuit for a feeding circuit, the circuit constitution is simplified, number of components is reduced and the device cost is decreased and the voltage loss by the feeding circuit is almost eliminated.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an intercom device, and in particular, in an intercom device that also supplies power from a base unit to a slave unit via a communication circuit, a power supply circuit connects a receiving speaker of the base unit to a power supply circuit. Regarding the technology used.

[Prior Art] FIG. 4 schematically shows a conventional intercom device. The intercom device shown in the figure includes a base unit 1 and a slave unit 5 connected to the base unit 1 via a call line 3. The base unit 1 includes a transmitting circuit including a transmitting microphone 7, a transmitting amplifier 9, etc., a receiving circuit, a speaker 11, and a coupling capacitor 1.
3, a power source 15, and a choke coil 17 for supplying the power to the communication line. The handset 5 includes a microphone 19 and a transmitting amplifier 21.
The receiver includes a transmitter circuit having a speaker 23, a coupling capacitor 23, and the like.

That is, in the intercom device shown in FIG. 4, the choke coil 17 is used as a power supply circuit, and operating power is supplied from the base unit 1 to the slave unit 5 via the communication line 3. In this case, since the choke coil 17 has a high impedance in terms of alternating current, it is possible to accurately supply one power source to the handset 5 without causing attenuation of the call signal or the like.

Further, FIG. 5 shows another conventional example of an intercom device.

In this device, a pseudo-inductance circuit having a transistor 27, resistors 29, 31, 33, and a capacitor 35 is used in place of the choke coil 17 of the power supply circuit in the device of FIG.

This pseudo-inductance circuit constitutes a so-called gyrator circuit, and has the property of having low impedance in direct current and high impedance in alternating current due to the function of the capacitor 35 connected between the base of transistor 27 and the power supply Vce. ing.

Therefore, in the device shown in FIG. 5 as well as in the device shown in FIG. 4, it is possible to supply operating power from the base unit 1 to the handset 5 via the call line 3 without affecting the call signal. Become.

[Means for Solving the Problems] However, in the conventional intercom device shown in FIG. 4, a choke coil is used in the power supply circuit, which makes the device large and expensive. Furthermore, if a too large direct current is passed through the choke coil, the core may become saturated, so it is necessary to use a choke coil with a large core that allows for a considerable margin.

Further, in the intercom device shown in FIG. 5, since the pseudo inductance circuit needs to operate as a transistor, it is necessary that a voltage of several volts exists between the power supply vcC and the communication line 3. For this reason, a power supply circuit using this pseudo-inductance circuit has the disadvantage of increased voltage loss.

SUMMARY OF THE INVENTION An object of the present invention is to provide an intercom device that has a simple circuit configuration, is inexpensive, and has a power supply circuit with extremely low power supply loss, in view of the problems with the conventional intercom device described above. .

[Means for Solving the Problems] An intercom device according to the present invention includes a base unit having at least a speaker for receiving calls, and at least a base unit connected to the base unit via a telephone line and receiving power from the base unit. It is equipped with one slave unit. In the base unit, the speaker is connected between the power output and the communication line to form a power feeding circuit.

[Function] In such an intercom device, the power output of the base unit is applied to the call line via the speaker, and power is supplied to the slave unit. Speakers usually have relatively low DC resistance and high AC resistance.

Therefore, almost no voltage loss occurs in the power supply circuit.

Furthermore, due to the high AC impedance, even if the speaker is connected to a telephone line, there will be no attenuation of the telephone signal or other adverse effects.

[Example] Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows a schematic configuration of an intercom device according to an embodiment of the present invention. The intercom device shown in the figure includes a base unit 31 and a slave unit 35 connected to the base unit 31 via a telephone line 33. The base unit 31 includes a transmitting circuit including a transmitting microphone 37 and a transmitting amplifier 39, a power source 43, and an output terminal (V cc
) and a call line 33 connected to a receiving speaker 4
1. The handset 35 has a microphone 45 for transmitting speech.
A transmitter circuit includes a transmitter amplifier 47, and a receiver circuit includes a receiver speaker 49, a coupling capacitor 51, and the like.

In the intercom device shown in FIG.
Current flows from the XvCC to the call line 33 via the speaker 41, and power is supplied to the handset 35. As a result, the respective circuits of the base unit 31 and the handset 35 operate, and a call is made between the two. That is, for example, the transmitted voice input to the microphone 37 of the base unit 31 is converted into a transmitted electrical signal, amplified by the Abu 39, and then sent to the slave unit 3 via the communication line 33.
The signal is applied to the speaker 49 of No. 5.

Conversely, the audio signal from the microphone 45 of the handset 35 is amplified by the amplifier 47 and applied to the speaker 41 of the base unit 31 via the call line 33.

When making such a call, the speaker 4 of the base unit 31
1 has a relatively low direct current resistance, the power supply Vcc is also applied to the slave unit 35 with almost no voltage loss. Further, since the speaker 41 has a relatively high AC impedance, the AC impedance in the communication line 33 does not decrease, and thus does not cause attenuation of the audio current or other adverse effects. Furthermore, since the speaker 41 was originally used in conventional intercom devices, no dedicated components are required as a power supply circuit.

FIG. 2 shows a specific configuration of a base unit used in the intercom device according to the present invention. The circuit shown in Figure 2 is
A hook detection transistor TRI that detects the hook state of the handset, a call detection transistor TR2, a communication circuit PNI, a microphone EMI for sending, and a speaker S for receiving a call.
Equipped with P1, hook switch HS, etc. Also, O
8l is a ringing tone oscillation circuit, PAL is a power amplifier circuit for outputting the ringing tone, and TMI and TM2 are timing circuits, respectively. Further, transistors TR7 and TR8 are transistors for controlling the power supply to the slave unit, and transistor TR8 is a transistor for controlling power supply to the communication circuit PNI of the base unit.

In the circuit shown in FIG. 2, when the handset goes off-hook, the transistor TRI is turned on, and when the call button is pressed on the handset, the transistor TR2 is turned off. Therefore, when there is a call from the handset side, the input of inverter I2 becomes high level and the output of inverter I2 becomes low level. This signal indicating the transition to a low level is delayed for a predetermined time by the timing circuit TMI, and then inverted and outputted from the inverter I3. In response, the ringing signal from the ringing tone oscillation circuit OSI is transmitted to the power amplifier circuit PAL.
The signal is applied to the speaker SPI via the speaker SPI, etc., and a ringing tone is output. When the main unit is off-hook in response to this call, terminals f and b of hook switch H8 are short-circuited and power supply Vec is applied to the base of transistor TR6 via transistor TRI diode CD2, hook switch H8, etc. Therefore, the transistor TRB is turned on, power is supplied to the communication circuit PNI of the base unit, and thereafter the communication state is entered. Further, in this case, the power supply Vcc is applied to the base of the transistor TR7 via the timing circuit TM2. As a result, the transistor TR7 is turned on, and hence the transistor TR8 is turned on, and the power supply Vcc is applied to one end of the communication line (terminal 3 of the connector CNI) via the receiver speaker SP1, the transistor TR8, and the diode CD7. Therefore, power is supplied from this terminal 3 to the handset via the telephone line.

FIG. 3 shows a circuit configuration of a child device used together with the parent device shown in FIG. The circuit in Fig. 3 is a telephone communication circuit for handset SNI,
It is composed of a speaker SPI, a microphone EMl, a hook switch H81, a diode bridge DB1, and the like. The communication circuit SN1 includes transistors TR31 and TR.
32, resistor R31°..., R38, capacitor C31,..., C34, etc. Diode bridge DBI consists of four diodes C
DL, CD2. CD3. It is composed of CD4. Furthermore, the series circuit of the resistor R32 and the speaker SP1 constitutes a line termination resistor.

In FIG. 3, when the handset of the handset is lifted and placed in an off-hook state, the hook switch H81 is switched from the state shown by the dotted line to the state shown by the solid line in the figure. As a result, the input of the diode bridge DBI is connected to the communication line connected to terminals 2 and 3 of the connector CNI via the hook switch HSI. Also, hook switch H
Since the contact h and d of 8I are in an oven state, the output of the diode bridge DBI is connected to the communication circuit SNl. As a result, the power supplied from the base unit 1 to the call line as described above is supplied to the call circuit SNI of the slave unit.

In this state, when the call button SW1 is pressed, that is, when the call button SWI is turned on, from the terminal 2 of the connector CNI to the contacts a-e of the hook switch H5I, the speaker spi, the resistor R32, and the contact of the call button SWI hook switch HSI. Connector CNI terminal 3 through f-b
A circuit leading to is formed. As a result, both lines of the communication line are short-circuited by a series circuit including the internal impedance of the speaker SP1 and the resistance of the resistor R32.

Therefore, the calling state is detected by increasing the current flowing through the call line in the base unit.

In the call state, the diode bridge DB! The telephone line and the telephone circuit SNl are connected via the telephone line. Therefore, the speech signal input from the microphone EMI is amplified by the speech circuit SNI and sent to the speech line via the diode bridge DBI. On the other hand, an audio signal from the base unit inputted from the telephone line is inputted to the speaker SP1 via contacts e-a of the hook switch HS1 and the capacitor 03B, and the signal from the base unit is received on the slave unit side.

[Effects of the Invention] As described above, according to the present invention, since the receiving speaker of the base unit is used in the power supply circuit, there is no need to use a dedicated circuit device such as a choke coil or a pseudo inductance circuit in the power supply circuit, and the circuit configuration can be improved. Simplification, reduction in number of parts,
It is possible to measure the decline in equipment prices. Further, it is possible to almost eliminate voltage loss due to the power supply circuit, and low voltage operation is possible even when the intercom device is driven by a battery, for example.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram showing a general configuration of an intercom device according to one embodiment of the present invention, and FIG. 2 shows a detailed configuration of a base unit in an intercom device according to another embodiment of the present invention. Fig. 3 is an electrical circuit diagram showing the detailed configuration of a handset that can be used with the main unit shown in Fig. 2, and Figs. 4 and 5 are schematic diagrams of conventional intercom devices, respectively. FIG. 2 is a block circuit diagram showing the configuration. 1.31. Main unit, 5,35. Child unit, 3.33. Call line, 7.37. Microphone, 9.39. Transmitting amplifier, 11.41. Base unit receiver speaker, 15.43. Power supply, 17; Choke coil, 19.4
5i microphone, 21.47: Amplifier for handset transmission, 23.49. Handset receiver speaker, 27: Transistor, 29.31, 33; Resistor, 35; Capacitor.

Claims (1)

[Claims] The base unit includes a base unit having at least a speaker for receiving calls, and at least one slave unit that is connected to the base unit via a communication line and receives power from the base unit, and the base unit has a power output and a power output. An intercom device characterized in that the speaker is connected to the call line and power is supplied to the handset via the speaker.