JPS5857945B2 - intercom device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intercom device having an additional function of notifying outside when an abnormal situation occurs indoors.

To achieve this goal with conventional intercom devices, the output circuit of the speech amplifier is connected to the handset at the same time as the alarm sound oscillator is operated to generate the alarm sound preferentially, regardless of whether the device is in standby mode or during a call. One method is to use a relay.

However, if such a relay is used, the intercom device becomes expensive.

The present invention provides an inexpensive intercom device without using relays or the like, and will be described below along with embodiments thereof.

In the drawing, 1 is a parent device, and 2 is a child device.

3 to 7 are connection terminals. 11 is a DC power supply, 12 is a switch to be operated in an emergency, 13 is an oscillator that generates an alarm signal, 14 is an oscillator that generates a ringing signal, 15
1 is a speech amplifier, 16 is a switching circuit, 17 and 18 are hook switches, 19 is a receiver, and 20 is a speaker that also serves as a transmitter.

21 to 23 are transistors, 24 to 31 are resistors, 32 to 36 are capacitors, 37 is a diode, and 38 is a hybrid transformer.

39 is a switch to be operated in case of emergency, 40 is a lamp, 41
4 is a communication circuit of the handset 2, and 42 is a speaker that also serves as a transmitter.

Next, the operation of this device will be explained.

What is shown in the figure shows the standby state of the main unit, and the transistors 2L22 and 23 are each in an off state.

If the handset makes a call (not shown), the terminal 6, hybrid coil 38. The switching circuit 16 is driven through the handset 19 and the resistor 31 to operate the ringing oscillator 14, and a ringing tone is generated from the speaker 20 which also serves as a transmitter.

Then, raise the handset of base unit 1 and hook switch 17.1.
8, the hook switch 17 turns on transistors 22 and 23, respectively, and puts the speech amplifier 15 into operation.

At the same time, the telephone current is supplied to the handset 2, and the hook switch 17 connects the speaker 20 to the telephone amplifier 1.
By connecting to the input terminal of No. 5, it is possible to intercept the communication circuit between the base device 1 and the handset 2.

Next, when the base unit 1 is in the standby state, that is, the hook switches 17 and 18 are in the state shown in the figure, when the emergency switch 12 is closed, a current is supplied from the power supply 11 through the resistor 24 to the resistor 25 and the base of the transistor 21, and the transistor T1 Rub it on.

Then, since the alarm sound oscillator 13 is operated and the transistors 22 and 23 are also turned on through the diode 37, a communication circuit between the base unit 1 and the slave unit 2 is simultaneously constructed as in the above explanation.

However, at this time, because the output of the alarm sound oscillator 13 is connected to the negative feedback terminal I of the telephone amplifier 15, that is, the input circuit has an opposite phase relationship with the output terminal of the telephone amplifier which has a differential amplifier as an input circuit. After power amplifying this signal, an alarm sound is generated from the speaker 42 built into the handset 2.

It is also clear that when the emergency switch 12 is closed while the base unit 1 is in the talking state, that is, the hook switch is switched, the standby mode operates in exactly the same manner as in the state.

The output terminal of the alarm sound oscillator 13 is connected to the negative feedback terminal of the telephone amplifier 15 through the resistor 26 because the speaker 20 is connected to the telephone amplifier 15 when the telephone is in the telephone state. This is to prevent the signal from attenuating and the alarm sound volume from becoming lower than the operation in the standby state.

Further, the emergency switch 39 is an external switch provided so that an alarm sound can be generated from a location separate from the base unit 1, and operates in exactly the same way as the emergency switch 12.

Further, the lamp L built in the handset 2 is a lamp that lights up at the same time as the alarm sound is generated by the operation of the emergency switches 12 and 39, and together with the alarm sound, it can further increase the effect of attracting the attention of people outdoors. .

As is clear from the above embodiments, according to the present invention, it is possible to provide an intercom device that can issue an alarm without using expensive parts such as relays.

Furthermore, since the number of mechanical contacts is kept to a minimum, reliability can be improved.

[Brief explanation of drawings]

The drawing is a wiring diagram of an intercom device according to an embodiment of the present invention. 1... Master unit, 2... Child unit, 12,39
...Switch, 13 ...Oscillator, 15
・・・・・・Telephone amplifier, 21.22.23・・・・
・Transistor.

Claims (1)

[Claims] 1. A first transistor that drives the alarm sound oscillator, a second transistor that turns on the telephone amplifier, a third transistor that supplies telephone current to the handset and deactivates the call switching circuit of the base machine, which is turned on during a telephone call. means for simultaneously turning on the second and third transistors to form a communication circuit; a switch to be operated in an emergency; operation of the switch turns on the first transistor; 3. An intercom device characterized in that there is provided a means for turning on transistors No. 3 at the same time, applying the output of the alarm oscillator to the speaker of the handset, and generating an alarm sound regardless of whether a call is in progress or not.