JPH0626376B2 - Automatic hold release device for telephone - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a telephone automatic hold canceling device in which a plurality of telephones are connected to one office line.

(Prior Art) In a conventional parent-child telephone using a plurality of telephones for one office line, when the user wants to transfer the call during a call, the call is put on hold and the telephone is picked up until another telephone answers again. I had to wait until I heard a call tone in the handset that the other handset answered or I confirmed that I picked up the handset. Some phones also had a hold function, but they do not have an automatic release function.Therefore, you can hold the handset while holding it up, or you can manually release the hold after confirming that you have answered with your eyes or ears. I had to.

(Problems to be Solved by the Invention) In the above configuration, while holding the hand,
Alternatively, there was a drawback that the call was accidentally cut.

An object of the present invention is to solve the drawbacks of the related art and to easily transfer a call without waiting for the response of the transfer partner by pressing the transfer button to put the station line on hold and returning the caller when transferring the call. Is to

(Means and Actions for Solving Problems) The automatic hold releasing apparatus for a telephone according to the present invention is a circuit A having a long time constant for monitoring and holding the station line voltage of the telephone during a call.
A circuit B having a time constant shorter than that of the circuit A; a circuit C which detects a voltage difference between the circuit A and the circuit B and outputs an output when the difference exceeds a certain voltage; and a hook switch. When inserted in parallel and held, the station line is closed instead of the hook switch, the station line is held and the circuits A, B and C are operated, and the station line is output by the output of the circuit C. When the other telephone connected in parallel on hold responds to the call, it detects that the station line voltage has decreased and automatically releases the telephone from the hold state. It has the function of ending the call.

(Embodiment) An embodiment of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 is a block diagram of an automatic hold releasing apparatus for a telephone according to the present invention. In the figure, 1 and 2 are office lines, to which telephones 3 ₁ to 3 _n in parallel are connected, and further a telephone 4 according to the present invention is connected. Reference numeral 5 is a hook switch, 6 is a telephone network, 7 is a hold and automatic hold release circuit, 8 is a relay contact, and 9 is a hold button.

During telephone 4 call circuit operates by pressing the hold button 9 for forwarding the call to another telephone 3 _1, by the relay contact 8 is turned on, even the call circuit at the handset relay contact 8 Is held by. Next, when the telephone 3 ₁ responds, two telephones, telephone 3 ₁ and telephone 4, make a call on _one station line, so that the voltage between the station lines ₁ and 2 drops by several volts.
At this time, the automatic hold release circuit 7 detects this voltage drop,
By turning off the relay contact 8, the telephone 4 is disconnected from the office line, and the transfer is completed.

FIG. 2 is a circuit diagram of the automatic hold canceling device of the present invention. The 10 is a latching relay of the second winding in the figure, busy office line voltage is charged to the resistor R ₁ 11, capacitor C ₁ 13 through the diode D ₁ 12. When the hold button 9 is pressed for holding, the charge of the capacitor C ₁ 13 is latching relay.
By discharging through the winding on one side of 10, the latching relay 10 is turned on, its contact 14 closes the hook switch 5, the handset is placed and the call is held even if the hook switch 5 is cut off. The office line voltage resistor R ₄ 15, the diode D ₂ 16, the resistor R ₄ 15 together to charge the capacitor C ₂ 17 loop of the capacitor C ₂ 17, the diode D ₃ 18, the resistor R ₇
19, the capacitor C ₃ 20 is also charged in the loop of the capacitor C ₃ 20. The discharge time constant of capacitor C ₂ 17 is resistor R ₅ 21, R
It is determined by ₆ 22 and capacitor C ₂ 17 and set to about 6 seconds, and the discharge time constant of capacitor C ₃ 20 is determined by resistor R ₈ 23 and capacitor C ₂ 17 and is about 10 seconds and longer by capacitor C ₂ 17. It is set. Phone 3 station line voltage when ₁ responds about 2
Or 5V, the electric charges of the capacitors C ₂ 17, C ₃ 20 gradually begin to discharge, but the time constant is different, so the capacitors C ₂ 17
Discharges quickly and the voltage difference between capacitors C ₂ 17 and C ₃ 20 is about 0.
Transistor Q ₃ 24 is turned on and become 7V. Turning on transistor Q ₃ 24 turns on transistor Q ₂ 25, causing current to flow through resistor R ₃ 26, causing transistor Q ₁ 27
Is turned on, the charged current of the capacitor C ₁ 13 flows through the other winding of the latching relay 10, the latching relay 10 is turned off, and the contact 14 is restored to disconnect the telephone circuit. The resistors R ₁ 11, R ₄ 15 are resistors for not affecting the AC impedance during a call, and the diodes D ₁ 12, D ₂ 16, D ₃ 18 are for preventing backflow, and R ₂ 28
Is a resistor for bias.

Also, the reason why the time constant of the discharging capacitor C ₂ 17 is set to be 6 to 10 seconds is that another telephone 3 _n mistakenly tries to make a call without knowing that another telephone 3 _n is busy (transferring), and already talks. This is to prevent the automatic hold release function from operating and disconnecting the call when the handset is returned in a hurry to know that it is inside.

In this embodiment, when trying to transfer a call and another telephone, simply press the transfer button and put the handset,
You can automatically transfer without having to wait for the transfer destination phone to reply again.

Although the latching relay is used in this embodiment, in a telephone using a microcomputer for dial control, a transistor can be used instead of the contact of the latching relay and the microcomputer can be controlled instead of the relay. In this case, by using the hook switch information, it is possible to easily stop the automatic hold release function when the telephone call is made again.

(Effects of the Invention) According to the present invention, when a plurality of telephones are connected to one office line and a call from one telephone is desired to be transferred to a telephone at another location, it is possible to automatically press a transfer button. The line is automatically released by putting the line on hold at the destination and the telephone at the transfer destination responding, so the conventional inconvenience of lifting the handset until the transfer destination responds is released. There is an effect that it is possible to prevent the call from being disconnected when the handset is accidentally dropped first.

[Brief description of drawings]

FIG. 1 is a block diagram of a device for automatically canceling hold of a telephone according to the present invention, and FIG. 2 is a circuit diagram thereof. 1, 2 ... Station line, 3 ₁ to 3 _n , 4 ... Telephone, 5 ... Hook switch, 6 ... Telephone network, 7 ... Hold and automatic hold release circuit, 8 ... Relay contact, 9 ... … Hold button, 10 …… Latching relay, 11,15,19,21,22,23,26,2
8 …… Resistor, 12,16,18 …… Diode, 13,17,20 ……
Capacitors, 14 contacts, 24, 25, 27 ... transistors.

Claims (1)

[Claims] 1. A circuit A having a long time constant for monitoring and holding a local line voltage of a telephone during communication, a circuit B having a time constant shorter than the circuit A, and voltages of the circuits A and B. When a difference is detected and the voltage difference exceeds a certain voltage, the circuit C that outputs an output is inserted in parallel with the hook switch, and when the holding operation is performed, the station line is closed instead of the hook switch. , A control circuit that holds the station line and operates the circuits A, B, and C to open the station line by the output of the circuit C, and responds on behalf of another telephone connected in parallel while on hold. In this case, the automatic hold releasing apparatus for a telephone has a function of detecting that the office line voltage has decreased and automatically releasing the hold of the telephone and ending the call.