JPH025077B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transfer method for transferring a call to another telephone without performing a hold operation in a button telephone device having a confidential call function and a loudspeaker receiving function.

Conventionally, transfer in a confidential button telephone device involves temporarily putting the line in progress on hold, and then pressing the line button corresponding to the line on hold on another telephone to enable the transfer call. However, since this method requires complicated operations, there is a demand for a transfer function that does not require holding operations. To this end, an effective method is to have the telephone that wants to receive the transfer (transferred telephone) press the line button in use on the transfer source telephone and wait, and then the call is switched when the call ends.

However, in this case, if a control method is adopted in which the transferee telephone is connected after the transfer source telephone is disconnected, an instantaneous disconnection signal is generated on the line, which is inconvenient.
To solve this problem, some conventional devices have a line-terminating resistor installed in the telephone set, and when the transferred telephone is in a forwarding standby state, this terminating resistor is connected in parallel to the line in use, and A method of switching from the terminating resistor to the talking circuit when the telephone ends a call is used. However, in this case, it is necessary to provide a terminating resistor and a switching circuit in the telephone, which poses the problem of making it difficult to make the telephone smaller and more economical.

This invention uses a loudspeaker receiving circuit inside the telephone to form a loop circuit during transfer standby, and is equipped with a switch that prohibits the sound from being emitted from the loudspeaker of the loudspeaker circuit during transfer standby, thereby maintaining confidentiality and making the device more compact and economical. This system is designed to avoid adverse effects on functional operations such as sending out ringtones, and will be described in detail below with reference to the drawings.

The figure shows an embodiment of the present invention, in which a line CO is accommodated in a key telephone main device ME, and telephones KT1 and KT2 are connected to the main device ME through a speech line SL and a control line DL, respectively. In the main device ME, the line CO and the line SL of the telephones KT1 and KT2 are connected and disconnected through the intersection points XT1 and XT2 of the line switch SW, respectively. The communication path switch SW is controlled by the main control circuit MC. Main control circuit MC is connected to control line DL. In the telephone KT1, a telephone switch HS is connected to one side of the communication circuit, and a handset HD is connected to the other side. The communication line SL is switched and connected to the switch HS and the coupling transformer T by the switching relay SR. The coupling transformer T separates the direct current from the communication line SL and supplies the audio signal to the loudspeaker receiving circuit LS. A switch is provided between the coupling transformer T and the loudspeaker circuit LS to control the input of the audio signal to the loudspeaker circuit LS.
CT is inserted. Loudspeaker receiving circuit LS is input amplifier
Consists of IA, output amplifier OA, and speaker SP.
The telephone control circuit KC receives information from the line selection button KEY, switch HS, control line DL, and various other buttons not shown in the diagram to perform various operations as a button telephone, and usually has a built-in microcomputer. ing. The output side of the paging sound source circuit OSC is connected to the input side of the output amplifier OA.

When the telephone KT1 is idle, the switch is switched off.
HS is open, switching relay SR is call circuit SC
Closed on the side. Also, the intersection point XT in the main device ME
1. XT2 is open.

First, the basic operation of the telephone KT1 will be explained.
When the handset HD is raised on the telephone KT1 and the line button KEY corresponding to the line CO is pressed, the switch HS contact closes and the call information is transmitted from the control circuit KC to the main control circuit MC through the control line DL.
The main control circuit MC closes the crossing point XT1 and the telephone KT
1 can make calls using line CO. At this time, when the function button KEY for loudspeaker reception is pressed, the control circuit KC closes the switching relay SR to the loudspeaker reception circuit LS side, closes the switch CT, and the audio signal from the line CO passes through the input amplifier IA and output amplifier OA. The sound is emitted from speaker SP. Also, when a call is received from another line, the main control circuit MC sends a call to the control circuit.
The incoming call information is transmitted to KC, and the control circuit KC drives the ringing sound source circuit OSC to generate a ringing sound from the speaker SP. At this time, since the input amplifier IA is present, the output signal of the ringing sound source circuit OSC does not mix into the communication line SL.

Next, the operation when performing transfer will be explained. In the figure, it is assumed that telephone KT2 is busy using line CO and telephone KT1 is idle. The handset HD is raised on telephone KT1 and the line
When the line button KEY corresponding to CO is pressed,
The switch HS is closed and the call information is transferred to the control circuit.
It is transmitted from KC to the main control circuit MC through the control line DL. Since the line CO is already in use, the main control circuit MC issues a waiting signal to the telephone set KT1 and also closes the intersection XT1 while maintaining the connection at the intersection XT2. Upon reception of the above-mentioned waiting signal, the telephone set KT1 sets the switching relay SR to the operating state switch CT to the open state. As a result, telephones KT1 and KT2 are multiple-connected to line CO, but telephone KT1's speech circuit SC and loudspeaker circuit LS are separated from line CO, and telephone KT2 is disconnected from line CO.
The secrets of will be kept.

At this time, when the telephone KT2 puts down the handset,
Disconnection information is transmitted to the main control circuit MC through the control line DL. Main control circuit MC is at intersection point XT2
and sends call permission information to telephone KT1. As a result, the control circuit KC restores the switching relay SR, and as a result, the call circuit SC is connected to the line CO, allowing transfer calls.

At this time, until the switching relay SR is switched, the DC loop of the line CO is held on the primary side of the transformer T, and even if the handset of the telephone KT2 is turned down, there will be no instantaneous interruption of the line. Furthermore, even if the telephone KT1 receives a call and the amplifiers IA and OA are activated during transfer standby, the switch CT is open, so the voice signal on the line CO will not be mixed into the ringer sound.

Control of the switch CT, operation of the switching relay SR during transfer standby, recovery of the switching relay SR by receiving call permission information, etc. can be easily achieved by creating a program for the microcomputer of the control circuit KC.

As described above, according to the present invention, a call can be transferred without performing a hold operation, and the operation can be simplified. Moreover, the circuit to realize this function utilizes the transformer T on the input side of the loudspeaker circuit that originally exists in the telephone.
Only a switch CT needs to be added, and it can be configured with simple changes, and (1) there is no momentary interruption in the DC loop of the line during transfer, (2) the confidential information of the transfer source can be maintained, etc. Transfer can be performed without adversely affecting the functionality of the device.

[Brief explanation of drawings]

The figure is a diagram showing an embodiment of a transfer method in a key telephone device according to the present invention. ME: Main device, KT1, KT2: Telephone, CO:
line, SL: speech line, DL: control line, SC: speech circuit, LS: loudspeaker receiving circuit, CT: switch, T: coupling transformer, MC: main unit control circuit, KC: telephone control circuit, SR: switching relay.

Claims (1)

[Scope of Claims] 1. In a button telephone device having secret call and loudspeaker receiving functions, the telephone has a speech circuit, a loudspeaker receiver circuit, and a coupling transformer connected to the speech line in an operating state,
The telephone set is provided with a switching relay that connects the telephone line to the telephone circuit in a non-operating state, and a switch provided between the coupling transformer and the loudspeaker receiving circuit, and the telephone set is housed in the same button telephone device. , when a line in use by another telephone is captured, the switching relay of the telephone is activated, the coupling transformer is connected in parallel to the line to form a loop, and the switch of the telephone is activated. A transfer standby state is created by disconnecting the loudspeaker receiving circuit and the call line as an open state, and a transfer call state is established by controlling the switching relay to be inactive when the other telephone ends a call. Transfer method in the button telephone device to obtain.