JPH0197045A - Telephone set - Google Patents

Abstract

PURPOSE:To attain talking with high quality by connecting a circuit with a line as an object the sending of a selection signal via a low impedance circuit only while a selection signal of key telephone system is sent and disconnecting the circuit from the line at the time of other talking. CONSTITUTION:A resistor R2, a diode D2 and a capacitor C1 in a low impedance circuit 10 at talking are disconnected from the line and only R1, D1, C1 forming a high impedance circuit are connected to the line and a minute current flowing to a R1 stores an electric charge to the capacitor C1 gradually. When a talker hooks off and desires dialing to depress a keyboard 9 to send a selection signal, a dialer IC8 detects the key depression, is started by the charge stored in the C1 and the selection signal transmission is started and an XMVTE reaches a GND level. Thus, a Tr1 is turned off, Tr2, Tr3 are turned on and low imped ance R2, D2 are connected to the VDD to acquire the current to operate consecu tively to the dialer IC from the line.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a telephone, and more specifically to a power supply current supply circuit thereof.

[Conventional technology]

Conventional telephones that are made up of active elements such as ICs and transistors and are driven by current from the telephone line consume a large amount of current when sending selection signals, especially those that use a button button system that uses a tone dial signal DTMF. Therefore, the active element was connected directly to the line or via a low impedance element, and was operated by being supplied with a large amount of current from the line.

FIG. 3 is an example of the block configuration of a conventional telephone set.
Reference numeral 4 indicates a ringing signal display circuit whose purpose is to notify the speaker of a call when in an on-hook state, and 4 indicates Ll.

Even if there is a polarity reversal between L2, a rectifier circuit is added to ensure stable operation of peripheral circuits 7 and 8, 5 is a hook switch that connects the line and the talking circuit side when off-hook, and 6 is used to make a call. For the purpose of this, the communication circuit 7 including active elements is a handset for making calls, 8 is a dialer IC for the purpose of sending selection signals, and 9 is a dialer IC which is an active element capable of sending out pushbutton type signals. Keyboard for selecting the selection signal. 14 drives 8 with the current from the line, and prevents the line current to 6 from being cut off and the operation of 6 becomes impossible, and at the same time, to 8,
This is a current supply circuit whose purpose is to prevent 8 from being destroyed due to excessive current flowing.

[Problems to be solved by the invention] In the above conventional example, when 8 sends out a selection signal using the pushbutton method, a large amount of current must be obtained from the line, and the current supply circuit 14 has a low impedance. I needed to.

This low impedance circuit was always connected to the line even when the keyboard in 9 was pressed and 8 was sending out a selection signal, such as during a call, making the operation of 6 unstable during a call. There are serious problems such as deterioration of call quality, deterioration of AC impedance, DC impedance return loss, and other characteristics of telephones during calls, and adverse effects on telecommunications line equipment. Ta.

[Means for Solving the Problems (and Effects)] In order to solve the above-mentioned problems, the present invention provides a selection signal via a low impedance circuit only while sending out a selection signal of the pushbutton type. By connecting a circuit for the purpose of signal transmission to the line and obtaining enough current for its operation, and during other calls, the low impedance circuit is disconnected from the line to stabilize the call circuit during calls. The aim is to ensure operation, improve various characteristics of the telephone such as DC impedance, AC impedance, and return loss, and ensure high call quality.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of the first embodiment of the present invention, in which 1 is a terminal L connected to a line.
,, , 2 are the same < L 2.3 is a calling signal display circuit, 4 is a rectifier circuit, 5 is a hook switch, 6 is a communication circuit, 7 is a handset, and 8 is a dialer IC.

9 is the keyboard, 10 is when 8 is sending a selection signal,
a current supply circuit that supplies power current from the line to 8 through the low impedance circuit, and in other states supplies power current from the line to 8 through the high impedance circuit;
R1-R5 are resistors, Trl-Tr3 are transistors, D
1+ D2 is a diode, C0 is a capacitor and lO
It is a component of

8 signal terminal V. D is a power input, and XMVTE is a signal terminal that is at GND level when a selection signal is being sent, and is at VOO level at other times. R1 and R4 are high impedance elements, and the current flowing therein is minute, so that the adverse effect on the communication circuit and the line side by connecting these to the line can be ignored.

Next, in the above configuration, when the telephone is not transmitting a selection signal, such as during a call, R2+ D2+ CI, which is a low impedance circuit of lO, is disconnected from the line;
Only R 1 +D, , C, which are high impedance circuits, are connected to the line, and the minute current flowing through R gradually stores charge in the capacitor C1.

Although this stored charge is not sufficient to operate the dialer IC 8 continuously for a long time, it is assumed that the operation of the dialer IC 8 is guaranteed for a short time after the IC 8 starts sending out the selection signal. Here, the voltage of the signal XMVTE is at the VDD level, and Tr1 is on, Tr2 is on, and Tr3 is off.

Next, when the speaker is off-hook and wishes to make a call and presses the keyboard 9 to send a selection signal, the dialer IC 8 detects the key press and is activated by the charge stored in C1 to select Start signal transmission and XMVTE becomes G
It becomes ND level. As a result, Trl turns OFF, Tr2
．． Tr3 is turned on and R2. D
2 is connected to VOO, and obtains a current from the line that allows the dialer IC to operate continuously. Next, when the speaker finishes pressing the keys and the dialer IC finishes sending out the selection signal, XMVTE becomes the vDD level and Trl is turned on.

Tr2. Tr3 is turned OFF, R2 and D2 are disconnected from the line from VOO again, and the initial state is restored.

[Other Examples]

FIG. 2 shows another embodiment in which a low impedance circuit is automatically interposed between the dialer IC and the line when the keyboard is pressed, regardless of the signal state of the dialer IC. 1 to 8 in the figure are the same as in FIG. Reference numeral 11 in the figure is a current supply circuit, which interposes a low impedance circuit between the line and the dialer IC while the keyboard is pressed down. Also, R, -R2
, D, ~D2 are the same as in FIG. SW1 is linked to the keyboard and is ON while the keyboard is pressed down, and OFF otherwise. In the figure, 12 is a signal line from the keyboard. In the figure, reference numeral 13 denotes a keyboard, which can be driven to turn on the SW via 12 when any one key is pressed, and to turn off otherwise.

In this embodiment, by using the special keyboard 13 as described above, the SW can be turned ON or OFF depending on the pressed state of the key.
F, and when the keyboard is not pressed, the low impedance circuit is disconnected from the line.

Further, in this embodiment, by using a special keyboard, Tr1 to Tr3. It eliminates the need for the electrical components R1-R6 and has a simplified circuit configuration, making it possible to save resources by reducing parts and provide inexpensive equipment by reducing the cost of telephones. This is effective for telephones in which the keyboard is pressed and the selection signal is sent out at the same time.

- As explained above, according to this embodiment, the power supply current of the selection signal sending circuit made up of active elements of the telephone is obtained from the line via the low impedance circuit only while sending out the selection signal of the pushbutton type. During other calls, etc., by disconnecting the low impedance circuit from the line, the button-type selection signal transmission can operate stably, while at the same time ensuring stable operation of the call circuit during calls. It is possible to improve the characteristics of direct current impedance, alternating current impedance, return loss, etc., and to ensure the quality of the call, which also eliminates discomfort for the speaker and prevents negative effects on the line side. can.

〔effect〕

As described above, according to the present invention, it is possible to conduct telephone calls stably and with high quality.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a telephone that is an embodiment of the present invention, and FIG. 2 is a block diagram showing the configuration of a telephone that is another embodiment of the present invention in which a special keyboard is used. Block Diagram FIG. 3 is a block diagram showing the configuration of a conventional telephone. 1 and 2 are telephone lines, 3 is a call signal display circuit, 4 is a rectifier circuit, 5 is a hook switch, 6 is a telephone call circuit, 7 is a handset, 8 is a dialer IC, 9 is a keyboard, l
O is a power supply circuit.

Claims (1)

[Claims] (1) means for supplying power with current from a telephone line;
A telephone set comprising dial signal sending means for sending a tone dial signal, and means for supplying power supply current from the power supply means to the dial signal sending means only while the dial signal sending means is in operation.