JP2006135625A - Interphone device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To put an impedance upper circuit, an overcurrent detecting circuit, a detection current sending-out circuit, and an ON/OFF circuit together in one circuit. <P>SOLUTION: An interphone device of the present invention is equipped with a door phone master device 2 which is connected to an entrance-door slave unit 1 through a two-wire cable L. The door phone master device 2 is equipped with the impedance upper circuit 23c which increases the impedance from electric power to the two-wire cable L to high impedance for a speech signal and also to low impedance for the electric power to superpose and transmit the electric power and a speech signal to the two-wire cable L during a talk and an overcurrent detecting circuit 23b which detects an overcurrent flowing if the two-wire cable L short-circuits in error. Then a control resistance constituting the impedance upper circuit 23c is used as a common resistance R5 of a detection resistance constituting the overcurrent detecting circuit 23b. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an interphone device, and more particularly to an interphone device including an impedance upper circuit, a detection current transmission circuit, an overcurrent detection circuit, and an ON / OFF circuit.

  Conventionally, as this type of intercom device, there has been provided a doorphone master unit installed in a living room of a house and an entrance slave unit connected to the doorphone master unit via a transmission path and installed at the entrance of the house. A call is detected by the call detection circuit of the doorphone master unit by operating the call button of the machine, and a call is made between the handset transmitter / receiver of the front handset and the master handset of the doorphone master by switching at the relay. It is known (see, for example, Patent Document 1).

  Here, the intercom base unit includes a call detection system power supply circuit that supplies a call detection system voltage to the entrance terminal via a call detection circuit and a relay at the time of standby and detection of a call, and a call detection system voltage at the time of a call. Includes a call power supply circuit that supplies different call system voltages to the entrance cordless handset via a call circuit and a relay, and the entrance cordless handset detects a voltage supplied from the doorphone master unit, and a voltage A power supply circuit for supplying power to the call circuit when the call system voltage from the call system power supply circuit is detected by the detection circuit.

  According to such an intercom device, it is possible to supply power only to the call circuit of the door phone and the door phone during a call between the door phone and the door, and to minimize power consumption. Energy saving can be achieved.

  By the way, in the intercom apparatus with such a configuration, the impedance from the power supply to the two-wire cable is increased to a high impedance with respect to the call signal in order to superimpose and transmit the power supply and the call signal to the two-wire cable during a call. An impedance upper circuit that has a low impedance to the power supply is installed. Further, as a peripheral circuit of the intercom device, an overcurrent detection circuit that detects an overcurrent that flows when a two-wire cable is accidentally short-circuited, and a standby A detection current sending circuit that supplies the current required to detect a call from the front door unit to the front door unit from the doorphone main unit, and a transition between the detection current sending circuit and the power source during standby and during a call Function that is independent from the ON / OFF circuit to turn on / off the power supply to the entrance cord It is mounted as a circuit having.

  As described above, in the conventional intercom apparatus, since the four circuits of the impedance upper circuit, the overcurrent detection circuit, the detection current transmission circuit, and the ON / OFF circuit are mounted as independent functions, the circuit configuration However, there is a problem that the number of parts increases and the cost increases.

JP 2001-211262 (paragraph numbers “0011” and “0012”, FIG. 1)

  The present invention has been made to solve the above-mentioned problems, and includes an impedance upper circuit, an overcurrent detection circuit, a detection current transmission circuit, and an ON / OFF circuit that are mounted as having independent functions. An object of the present invention is to provide an intercom apparatus that can simplify the circuit configuration by concentrating on a circuit.

  In order to achieve the above-described object, the intercom apparatus according to the first aspect of the present invention connects the entrance cordless handset and the doorphone master set with a two-wire cable, and responds to the call button operation of the visitor in the entrance cordless handset. Interphone device that makes a call between the handset transmitter / receiver of the front door slave and the master phone transmitter / receiver of the doorphone master unit. The doorphone master unit transmits the power and call signal superimposed on the two-wire cable during a call. In order to increase the impedance from the power source to the two-wire cable to a high impedance with respect to the call signal, and as a control resistor of the impedance upper circuit that becomes a low impedance to the power source, and when the two-wire cable is accidentally short-circuited A common resistor is used as a detection resistor of an overcurrent detection circuit that detects a flowing overcurrent.

  According to a second aspect of the present invention, in the intercom device according to the first aspect, a current required for detecting a call from the front cordless handset to the two-wire cable during standby is transmitted from the doorphone main unit to the front handset. A resistor is connected as a detection current sending circuit to be supplied.

  According to a third aspect of the present invention, in the intercom device according to the second aspect, the power supply to the entrance cordless handset is turned on between the detection current sending circuit and the power source according to the state transition during standby and during a call. A transistor is connected as an ON / OFF circuit for turning off / off.

  According to the intercom apparatus of the first to third aspects of the present invention, the impedance upper circuit, the overcurrent detection circuit, the detection current transmission circuit, and the ON / OFF circuit that operate as having independent functions are combined into one. By concentrating on the circuit, it is possible to simplify the circuit configuration of the door phone master unit, thereby reducing the number of parts and reducing the cost.

  Hereinafter, a preferred embodiment to which an interphone device of the present invention is applied will be described in detail with reference to the drawings.

  FIG. 1 is a block diagram of an intercom apparatus according to an embodiment of the present invention.

  Referring to FIG. 1, a television intercom apparatus according to the present invention includes an entrance cordless handset 1 installed at the entrance of a house and an intercom master phone 2 installed in a living room of the house. Are connected to the doorphone master unit 2 via a two-wire cable L composed of a second cable.

  The entrance handset 1 includes a camera 11 for imaging a visitor, a call button 12 for calling the doorphone base unit 2, a handset microphone 13a for transmitting voice from the entrance handset 1 to the doorphone base unit 2, and a doorphone parent. And a handset transmission / reception device 13 including a handset speaker 13b for transmitting voice from the handset 2 to the entrance handset 1.

  The intercom base unit 2 includes an interface (hereinafter referred to as “I / F”) circuit 21 for connection to the entrance slave unit 1, a call detection circuit 22 that detects a call from the entrance slave unit 1, and the entrance at the time of standby. A detection current sending circuit 23a for supplying a current necessary for detecting a call from the handset 1 to the entrance handset 1 from the doorphone base unit 2 is detected, and an overcurrent that flows when the two-wire cable L is short-circuited is detected. The overcurrent detection circuit 23b increases the impedance from the power supply to the two-wire cable L to a high impedance (for example, about 600Ω) with respect to the call signal in order to superimpose and transmit the power supply and the call signal to the two-wire cable L during a call. At the same time, between the power supply and the impedance upper circuit 23c and the detection current sending circuit 23a, which have a low impedance (for example, about 0Ω) with respect to the power supply An aggregating circuit 23 for aggregating an ON / OFF circuit 23d for respectively turning on / off the power supply to the entrance cordless handset 1 according to the state transition, and a demodulating circuit for demodulating the FM video signal sent from the entrance cordless handset 1 24, the LCD 25 for displaying the video imaged by the camera 11, the call circuit 26, the base unit microphone 27a for transmitting voice from the door phone base unit 2 to the front unit 1 and the voice from the front unit 1 as the door phone base unit. 2, a parent device transmitter / receiver device 27 including a parent device speaker 27 b, a power supply circuit 28 that supplies power to each unit (circuit), a control circuit 29 that controls each unit (circuit), and a visitor call button And a loudspeaker 30 that reports a ringing tone in response to twelve operations. Here, the control circuit 29 is connected to the call detection circuit 22, the aggregation circuit 23, the call circuit 26, the power supply circuit 28, and the loudspeaker 30. The I / F circuit 21 is connected to the two-wire cable L, the call detection circuit 22, the aggregation circuit 23, the demodulation circuit 24, and the call circuit 26. The demodulation circuit 24 has an LCD 25, and the call circuit 26 has a master unit. A master microphone 27a and a master speaker 27b are connected as the receiver 27.

  As shown in FIG. 2, the aggregation circuit 23 includes first to fourth transistors TR1 to TR4, first to ninth resistors R1 to R9, and first and second capacitors C1 and C2. Yes. Here, one side of the first resistor R1 is connected to one cable constituting the two-wire cable L via the collector of the first transistor TR1 and the I / F circuit 21, and the other side is a third resistor. One side of R3, the collector of the third transistor TR3, and one side are connected to the other side of the fourth resistor R4 grounded. The emitter of the first transistor TR1 is connected to one side of the fifth and seventh resistors R5 and R7, and the base is one side of the sixth resistor R6, one side of the first capacitor C1, and the first side. It is connected to the emitter of the second transistor TR2. Further, the collector of the second transistor TR2 is grounded via the second resistor R2, and the base is connected to one side of the second capacitor C2 and the other side of the third resistor R3. The second cable constituting the two-wire cable L is grounded.

  On the other hand, the emitter of the fourth transistor TR4 is the other side of the fifth and sixth resistors R5 and R6, the other side of the first and second capacitors C1 and C2, the emitter of the third transistor TR3, Connected to one side of the resistor R8 and the power supply circuit 28, the collector is connected to the control circuit 29, and the base is connected to the other side of the seventh resistor R7. The base of the third transistor TR3 is connected to the control circuit 29 via the other side of the eighth resistor R8 and the ninth resistor R9. In the following description, the emitter of the fourth transistor TR4, the other side of the fifth and sixth resistors R5 and R6, the other side of the first and second capacitors C1 and C2, and the third transistor TR3 Each connection point on one side of the emitter and the eighth resistor R8 is defined as a first connection point A, the other side of the first resistor R1, the one side of the third resistor R3, the other side of the fourth resistor R4, and Each connection point of the collector of the third transistor TR3 will be described as a second connection point B.

  Next, the operation of the intercom apparatus of the present invention configured as described above will be described.

  First, the first to fourth transistors TR1 to TR4, the first to ninth resistors R1 to R9, and the first and second capacitors C1 and C2 are connected as shown in FIG. The resistor R1 functions as a detection current transmission circuit 23a as described later, and the fourth transistor TR4 and the fifth and seventh resistors R5 and R7 function as an overcurrent detection circuit 23b as described later. The first and second transistors TR1 and TR2, the second to sixth resistors R2 to R6, and the first and second capacitors C1 and C2 have a function as an impedance upper circuit 23c as described later. The transistor TR3 and the eighth and ninth resistors R8 and R9 have a function as an ON / OFF circuit 23d as will be described later. Here, as will be described later, the fifth resistor R5 is commonly used as a detection resistor of the overcurrent detection circuit 23b and a control resistor of the impedance upper circuit 23c. Therefore, in the following description, as the common resistor R5 explain. The first resistor R1 as the detection current sending circuit 23a is normally a resistor of about 2.2 kΩ, and is configured to supply a current of about 3 mA, and the first resistor as the impedance upper circuit 23c. Since the transistor TR1 and the common resistor R5 supply a large current to the entrance cordless handset 1, large components that can withstand the large current are used.

  In the intercom apparatus having such a configuration, at the time of standby, the control circuit 29 controls, so that the base potential of the third transistor TR3 is lower than the potential of the first connection point A (about 16V) (0 to 0). When the base of the third transistor TR3 is set to a low level potential, the third transistor TR3 is turned on, whereby the base potential of the second transistor TR2 is The potential becomes substantially the same as that of the first connection point A through the third transistor TR3. Then, the second transistor TR2 is turned off, and the base current does not flow through the first transistor TR1, so the first transistor TR1 is also turned off. Accordingly, in this state, since the first transistor TR1 is OFF, the power supply circuit 28 does not supply power for operating the entrance cordless handset 1 via the first transistor TR1.

  On the other hand, since the potential at the second connection point B is substantially the same as that at the first connection point A via the third transistor TR3, the first connection point A and the third connection point A are supplied from the power supply circuit 28. A current (power source) necessary for detecting a call from the front cordless handset 1 is supplied via the transistor TR3, the second connection point B, and the first resistor R1 as the detection current sending circuit 23a. Here, since the entrance cordless handset 1 consumes little current during standby, there is no voltage drop due to the first resistor R1, and even if power is supplied through the detection current sending circuit 23a, the two-wire The DC voltage between the first and second cables constituting the cable L is at a high level.

  In such a state, when a visitor presses down the call button 12 of the entrance cordless handset 1, the entrance cordless handset 1 starts to operate, and current consumption increases, so that the first, The DC voltage between the second cables decreases due to the voltage drop caused by the first resistor R1, and becomes a low level.

  When such a low level voltage is detected by the control circuit 29 via the call detection circuit 22, a ringing tone is reported from the loudspeaker 30 under the control of the control circuit 29. At the same time, the control circuit 29 controls the base potential of the third transistor TR3 to be set to the same level (about 16V) as the potential at the first connection point A, and the base of the third transistor TR3 is set. Is set to a high level potential, the third transistor TR3 is turned off. As a result, the base potential of the second transistor TR2 becomes the potential at the time of operation, so that the second transistor TR2 is turned ON, and a current flows through the base of the first transistor TR1, whereby the first transistor TR1. Is turned on, and the first transistor TR1 starts operating as a power supply circuit. Therefore, in this state, the power supply circuit 28 is connected to the entrance terminal 1 via the first connection point A, the common resistor R5, the first transistor TR1, the I / F circuit 21, and the two-wire cable L. The operating power is supplied.

  As a result, the video of the visitor is captured by the camera 11, and the captured video passes through the two-wire cable L and the I / F circuit 21 as an FM video signal that is FM-modulated via a modulation circuit (not shown). And sent to the demodulation circuit 24. The FM video signal is demodulated by the demodulation circuit 24 and transmitted to the LCD 25, whereby the video of the visitor is displayed on the LCD 25.

  Here, when the resident confirms the visitor based on the ringing sound reported from the loudspeaker 30 and the video image displayed on the LCD 25 and picks up the base unit transmission / reception device 27, the base unit transmission / reception is performed. A two-wire cable L is used between the call function (master microphone 27a and master speaker 27b) of the device 27 and the call function (slave microphone 13a and slave speaker 13b) of the slave transmission / reception device 13. A speech path is formed. Thereby, the resident can talk with the visitor. In addition, when the resident returns the parent device transmission / reception device 27 to the doorphone parent device 2 in order to end the call with the visitor, the doorphone parent device 2 shifts to a standby state.

  Next, the operation of the overcurrent detection circuit 23b will be described. First, when the third transistor TR3 is turned off and the first transistor TR1 starts operating as a power supply circuit, the first and second wires constituting the two-wire cable L due to the lack of wiring during construction of the interphone device When the two cables are short-circuited, an overcurrent flows through the first transistor TR1 and the common resistor (fifth resistor) R5. Here, if the resistance value of the common resistor R5 is, for example, 1Ω, a voltage of about 0.6V is generated at both ends of the common resistor R5 due to an overcurrent of about 0.6A, for example, and this voltage is the base of the fourth transistor TR4. -Applied between the emitters, thereby turning on the fourth transistor TR4.

  When the fourth transistor TR4 as the ON / OFF circuit 23d is turned on, an overcurrent detection signal is sent from the ON / OFF circuit 23d to the control circuit 29, and when the overcurrent detection signal is detected by the control circuit 29, As a result of the control of the control circuit 29, the base potential of the third transistor TR3 is set to a low level potential of about 0 to 5V as described above. When the base potential of the third transistor TR3 is set to a low level potential, the first transistor TR1 is turned off as described above, so that the first transistor TR1 is supplied from the power supply circuit 28 as described above. The power supply to the entrance cordless handset 1 via is stopped.

The block diagram of the intercom apparatus in one Example of this invention. The block diagram of the aggregation circuit in the intercom apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Entrance cordless handset 12 ... Call button 13 ... Handset transmission / reception apparatus 2 ... Door phone master 23a ... Detection current sending circuit 23b ... Overcurrent detection circuit 23c ... Impedance Upper circuit 23d: ON / OFF circuit 27: Base unit transmission / reception device TR3: Transistor (third transistor)
R1... Resistance (first resistance)
R5: Common resistance (fifth resistance)
L ... 2-wire cable

Claims (3)

The entrance cordless handset (1) and the doorphone master set (2) are connected by a two-wire cable (L), and the cordless handset of the entrance cordless handset is operated according to the operation of the call button (12) of the visitor in the entrance cordless handset. An interphone device for making a call between a transmitter / receiver device (13) and a parent device transmitter / receiver device (27) of the doorphone master unit,
The door phone master unit increases the impedance from the power source to the two-wire cable to the high impedance with respect to the call signal in order to superimpose and transmit the power source and the call signal to the two-wire cable during a call. As a control resistor of the impedance upper circuit (23c) having a low impedance with respect to the common resistor (as a detection resistor of an overcurrent detection circuit (23b) that detects an overcurrent that flows when the two-wire cable is accidentally short-circuited ( R5) is used.   The two-wire cable has a resistor (R1) as a detection current sending circuit (23a) for supplying a current necessary for detecting a call from the entrance cordless handset to the entrance cordless handset during standby. The intercom apparatus according to claim 1, wherein the intercom apparatus is connected. A transistor (TR3) serving as an ON / OFF circuit (23d) between the detection current sending circuit and the power source for turning on / off the power supply to the entrance unit according to the state transition during standby and during a call. 3) The intercom apparatus according to claim 2, wherein the intercom apparatus is connected.

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