JPS62204646A - Telephone set - Google Patents

Abstract

PURPOSE:To block the generation of a pseudo call tone by disconnecting an electric communication line, a selection signal generating circuit and a call signal detection circuit at off-hook. CONSTITUTION:When a caller hooks up a handset 7, the off-hook state is attained, the contact terminals 1a, 1c of a hook switch 1 are closed to connect the electric communication line to a selection signal generating circuit 4 and a channel network circuit 6. When the caller depresses a ten-key 8 in this state to select a desired signal, the selection signal generating circuit 4 sends a dial pulse or a DTMF signal to the line. Since a call signal detection display circuit 2 is disconnected from the line in this case, no ringer rings.

Description

[Detailed description of the invention] [Industrial application field] TECHNICAL FIELD The present invention relates to a telephone, and in particular to its construction.

[Conventional technology]

A conventional telephone has, for example, a configuration as shown in a block diagram in FIG.

L + , L 2 is a connection terminal with a telecommunications line, 21
is a hook switch (
2 is a calling signal detection/display circuit, 4 is a selection signal generation circuit, 5 is a line switch, 6 is a communication network circuit, 7 is a transmission,
A handset with a telephone receiver and a numeric keypad 8 are each connected with required wiring.

With the above configuration, when the caller presses the numeric keypad 8 in an off-hook state, the selection signal generating circuit 4 sends a selection signal corresponding to the pressed number to the line.

In addition, selection No. 43 has a dial pulse method and a DTM
F (Dual Tone Multi Frequency
For example, the dial pulse method sends out a selection signal by opening and closing a DC circuit. This shows an example of voltage. The transmission frequency in this case almost matches the frequency of the calling signal from the exchange.

(Problem to be solved by the invention) In order for the sending frequency and the calling No. 13 frequency to match,
Normally, the amplitude level of the ringing signal must be greater than the amplitude level of the dial pulse signal, and the ringing signal transmitted from the exchange must have a large amount of energy. Furthermore, the sensitivity level of the calling signal detection circuit has to be set to a level such that it does not respond to dial pulses but only responds to the calling signal, which is a design constraint.

Furthermore, similarly to the above, is it necessary to design telecommunications equipment so that the amplitude of the dial pulse signal sent from the terminal equipment is smaller than the ringing signal sent from the line at the input of the ringing signal detection circuit? As a result, the design of telecommunications lines was also constrained.

If terminal equipment such as telephones and supplementary line equipment are designed without considering the following conditions, the ringing signal detection/display circuit will be driven by dial pulses and even though the selection signal is being sent, First, there was a problem in that a ringer or the like was used to indicate that a call was being made, and the caller had to endure the harsh noise that could be called noise.

[Means for solving problems]

In order to improve the above-mentioned drawbacks of the conventional example, the present invention comprises a hook switch with a switching means to disconnect the telecommunications line, the selection signal generation circuit, and the calling signal detection circuit when off-hook.

That is, the present invention prevents the ringing signal detection circuit from ringing due to the dial signal, eliminates unpleasant pseudo-ringing tones, and at the same time reduces design constraints of telecommunications line equipment, telephones, etc. The purpose is

〔Example〕

Hereinafter, a first embodiment of the present invention will be described based on FIG.

L, , L2 are connection terminals for connecting to a telecommunications line, 1 is a changeover switch having a connection terminal 1a leading to the connection terminal L1, a contact 1b on the side of the calling signal detection/display circuit, and a contact 1c on the side of the communication network circuit. This is a hook switch, which closes the circuit through the contact 1b when the hook is on, and switches and closes the circuit through the contact 1c when the hook is off. 2 is a ringing signal detection/display circuit that detects a ringing signal and notifies the caller of the call by making a ringer sound; 3 is a connection terminal; L;
A rectifier circuit 5 is added to ensure stable operation of the selection signal generation circuit 4, which can send dial pulses even if there is a polarity reversal between the two, and the communication network circuit 6, which is used for making calls. Line switch for sending dial pulses,
7 is a handset, and 8 is a numeric keypad for specifying a telephone number.

Next, to explain the operation, in FIG. 1 showing the on-footer state, when the caller picks up the handset 7, the handset 7u goes into the off-hook state, and the hook switch 1
The connection terminal 1a and the contact 1c are closed to connect the telecommunication line to the selection signal generation circuit 41 and the communication network circuit 6fill. In this state, the caller selects the desired selection number 13 on the numeric keypad.
When selected by pressing , 1 selection A No. 3 generation circuit 4 selects dial pulse or DTM according to the selection.
Send the F signal to the line. At this time, the call No. 18 detection/display circuit 2 is in a state separated from the supplementary line, so no operation such as 1β movement of the ringer is performed even if any selection signal is sent to the line. Furthermore, when the caller puts down the handset 7, that is, in the on-hook state, the hook switch 1 switches to the contact lb side and connects the ringing signal detection/display circuit 2 to the line.
Similar to a normal telephone, when a call is received, the additional note detection/display circuit 2 is activated by the ringing signal.

Note that if the changeover switch used in the hook switch 1 is difficult to handle manually for some reason, an equivalent circuit can be constructed using two on/off switches. However, in this case, the number of switches increases, so it is inferior to the supplementary changeover switch in terms of cost and reliability.

Next, a second embodiment will be explained with reference to FIG.

In this embodiment, in the circuit of the first embodiment, a high impedance resistor 12 is added separately between the connection terminal 1a of the hook switch 1 and the contact IC, so that the selection signal generation circuit 41 can communicate even in the on-hook state. A minute current is made to flow through the network circuit 6 side.

Therefore, if the supplementary note generation circuit 4 and the communication network circuit 6 have memory, memory backup is possible with this minute current.

Furthermore, since the resistor 12 has a high impedance and the line current is very small, the exchange on the line side will not determine that the telephone is in an off-hook state.

Next, a third embodiment will be explained with reference to FIG.

In this embodiment, a constant current diode 13 is provided in place of the resistor 12 of the second embodiment at the same location.

Generally, the magnitude of line current is not constant as it is influenced by the impedance of transmission lines and terminal equipment. Therefore, when the selection signal generation circuit 4 and the communication network circuit 6 use the ``1'' flow such as memory backup, there is a possibility that the operation will not be stable. A constant current diode 13 is used, and when on-hook, a constant minute current is passed from the line to the 111 generation circuit 4 and the communication network circuit 6, and these circuits 4.
6 has been modified to ensure stable operation.

〔Effect of the invention〕

As explained above, the present invention is a structural feature of a telephone that employs a switching means in a hook switch. By making only minor changes, it is possible to completely prevent the generation of unpleasant pseudo-ring tones when sending selection signals, reduce design constraints on telecommunications line equipment and telephone equipment, and further reduce the number of calls sent from exchanges. This has the effect of enabling new telecommunications with low signal energy.

In addition, by adding a resistor or constant current diode to the hook switch, it is possible to back up memory using a minute current from the telecommunications line, which is effective for driving dial ICs with one-touch dialing functions. It also has the advantage of bringing

[Brief explanation of drawings]

FIG. 1 is a block configuration diagram of a telephone according to the first embodiment of the present invention, FIG. 2 is a diagram corresponding to FIG. 1 of the second embodiment, and FIG. 3 is a diagram equivalent to FIG. 1 of the third embodiment. 4 is a block diagram of a conventional telephone set, and FIG. 5 is a waveform diagram showing an example of electrical characteristics between line connection terminals when sending a selection signal of the dial pulse system. 1...Hook switch 2...Call signal detection/display circuit 4...
Selection signal generation circuit 6...Communication network circuit 12...Resistor 13-...Voltage relationship between constant current diode line connection terminals Figure 5

Claims (2)

[Claims] (1) A telephone equipped with a ringing signal detection circuit, a selection signal generation circuit, a communication network circuit, and a hook switch, which connects the telecommunications line to the ringing signal detection circuit when on-hook, and connects the selection signal generation circuit and the selection signal generation circuit when off-hook. A telephone set, characterized in that the hook switch is constituted by a switching means connected to a telephone network circuit. (2) The telephone set according to claim 1, wherein the hook switch has a switching means added to the switching means for supplying a minute current to the selection signal generation circuit and the communication network circuit when on-hook.