JPS6354278B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ring tone transmission circuit for transmitting a ring tone in a button telephone device having a function of outputting a voice signal input from a telephone line through a speaker.

In a button telephone device equipped with a so-called loudspeaker reception function that amplifies and broadcasts the audio signal from the telephone line, the same speaker circuit is used for the loudspeaker reception and for sending out a ringtone. is common. However, if the signal in each case is input directly to the speaker circuit input, if a call is received from another line during loudspeaker reception, the ringtone will mix into the call line and interfere with the call. had. For this reason, conventional devices of this type have a configuration in which the input to the speaker circuit is switched and supplied in the above two cases. For this reason, when a call is received during loudspeaker reception, the ring tone cannot be transmitted, and the caller is left unanswered for a long time even though he or she hears the ring tone. .

In order to eliminate the above-mentioned drawbacks, this invention mixes a low-volume ring tone signal into the speaker circuit in response to an incoming call during loudspeaker reception, and emits the ringtone during loudspeaker reception without disturbing the call significantly. The drawings will be described in detail below.

The figure shows one embodiment of the invention, a button telephone
KT is connected to the main device ME with a pair of communication lines SL and a pair of control lines DL. Generally, a plurality of key telephones KT are connected to the main device ME in a star pattern, and through the main device ME it is possible to make calls to outside lines and to make calls between the key telephones. In the telephone KT, the handset HD is connected to one side of the communication circuit SC,
A hook switch HS is connected to the other side. The communication line SL is switched by switching relay SR.
It is switched and connected to the HS and the coupling transformer T. The coupling transformer T separates the direct current of the communication line SL,
It supplies audio signals to the speaker circuit LS. In the speaker circuit LS, the output amplifier circuit OA is connected to the input amplifier circuit FA connected to the coupling transformer T.
Speakers SP are connected sequentially. In addition, the incoming sound source circuit OSC is connected to the connection point of the amplifier circuits IA and OA through the variable attenuation circuit ATT. control circuit
The KC performs various controls necessary for a key telephone, and can be configured using a so-called microcomputer. A loudspeaker button SK for performing loudspeaker reception is connected to the control circuit KC, and other buttons, such as a dial operation button, a central office line selection button, and an extension selection button, are also connected although not shown in the figure.

In the above configuration, the switching relay SR is always closed to the call circuit SC side, and when the handset HD is raised, the switch HS is closed, the call line SL is connected to the call circuit SC, and a call is possible. When the loudspeaker button SK is pressed, the switching relay SR closes to the transformer T side, and the audio signal from the communication line SL is transferred to the transformer T,
The sound is emitted from the speaker SP through the input amplifier circuit IA and the output amplifier circuit OA, and a loudspeaker reception state is established.

Next, the operation when receiving a call will be explained. When the telephone KT receives an incoming call, the incoming information is input from the main device ME to the control circuit KC through the control line DL. control circuit
KC drives the ringtone source circuit OSC to generate a ringtone. The control circuit KC further determines whether or not the telephone KT is in the loudspeaker receiving state, that is, whether the switching relay SR is operating.If the telephone KT is not in the loudspeaker receiving state, the attenuation amount of the attenuation circuit ATT is set to zero, If it is, the attenuation circuit ATT attenuates the ringtone.

Because of this configuration, the phone KT
When the telephone KT is in the idle state, a ringtone of sufficient volume is sent out from the speaker SP, and when the telephone KT is in the loudspeaker reception state, the ringtone is mixed into the call at a volume that does not interfere with the receiving sound and is output from the speaker SP.
A voice is emitted from SP. Furthermore, when the ring tone signal is supplied to a stage subsequent to the input amplifier circuit IA as in this embodiment, the presence of the input amplifier circuit IA prevents the ring tone signal from being mixed into the communication line SL. Even if a ringtone signal is supplied to the input side of the input amplifier circuit IA, the ringtone signal will be attenuated in response to an incoming call in the loudspeaker reception state, so even if this signal gets mixed into the communication line SL,
There is no risk of significant interference with calls. Even if you are not in the loudspeaker receiving state, by attenuating the ring tone signal for calls using the communication circuit SC, the loud ring tone will not reach the person using the HD handset, thereby preventing interference with the call. It is possible to prevent this.

If a microcomputer is used as the control circuit KC, controlling the attenuator ATT according to various conditions can be easily performed by setting various conditions necessary for the control and referring to the conditions. can do.

As described above, according to the present invention, even when an incoming call is received during loudspeaker reception, it is possible to send out a ring tone using one speaker, thereby prompting the user to respond to the incoming call. Moreover, the volume of the incoming call is attenuated, so there is less interference with the incoming call, and
Since large unnecessary signals are not mixed into the communication line, the caller does not feel uncomfortable. Furthermore, the circuit of the present invention has a simple configuration and is highly economical.

[Brief explanation of the drawing]

The figure is a block diagram showing an embodiment of a ring tone sending circuit according to the present invention. KT: button telephone, ME: main device, SL: speech line, DL: control line, SC: speech circuit, IA: input amplifier circuit, LS: speaker circuit, OA: output amplifier circuit,
SP: Speaker, OSC: Ring sound source circuit, ATT: Attenuation circuit, KC: Control circuit, SR: Switching relay,
SK: Loudspeaker button.

Claims (1)

[Claims] 1. A ring tone source circuit that generates a ring tone signal in a button telephone, which has a loudspeaker reception function that amplifies the voice signal input from the telephone line using an amplifier circuit, supplies the amplified signal to a speaker, and emits the sound from the speaker, and a ring tone source circuit that generates a ring tone signal, and an attenuation circuit that passes a ringtone signal from a sound source circuit and supplies it to the amplifier circuit; and means for controlling the attenuation circuit when a call is received in a loudspeaker reception state to attenuate the ringtone signal more than when a call is received in a no-call state. A ring tone transmission circuit for a button telephone equipped with.