JPS61112460A - Automatic answering telephone set - Google Patents

Abstract

PURPOSE:To detect surely the operation stop of an automatic answering telephone set by utilizing a line supervisory pulse generated for plural number of times after on-hook of a caller. CONSTITUTION:When a caller hooks on, since the line supervisory pulse is generated for plural number of times, a public transistor of a photocoupler 9 is turned on/off. Then the electric charge of a capacitor 20 is discharged by the on/off of the transistor (TR), TRs 21,23 are turned on and this stage is held. The holding output is detected by a system control circuit 10 and an output RL goes to logical 1. Then the TR 12 is turned off and no current is fed to a relay 14, then a relay contact 2 is turned off to interrupt telephone lines L1,L2 to a tape recorder.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is equipped with, for example, a tape recorder, and when a call is received while the user is away, the playback sound of the tape is sent to the calling party.
The present invention relates to an answering machine that operates as an answering machine, such as recording the caller's necessary matters on a tape recorder, and particularly relates to a technique for stopping the above-mentioned answering machine.

[Conventional technology]

Conventionally, in this type of answering machine, when the answering machine for tape recorder playback or recording was to be terminated, it was done by detecting the instantaneous line current off pulse that occurs when the central office switches trunks when the caller is on-hook. method was used.

[Problem that the invention seeks to solve]

However, the instantaneous line current OFF pulse that occurs when switching a transformer at a telephone office is difficult to generate depending on the exchange, or occurs only once, making detection of the pulse extremely unstable. For this reason, there is a disadvantage that unnecessary recordings after the caller goes on-hook increase, and the tape is wasted. Furthermore, there is a possibility that the system cannot prepare for the next caller's call.

[Means for solving problems]

Some modern telephone exchanges generate the following signal on the other party's line when a caller goes on-hook.

In other words, Fig. 2 shows the progress of the signal generated on the other party's line. When the calling party goes on-hook at time t, the other party's line receives a silent period and a busy tone at a constant DC voltage. The superimposed period - a silent period occurs sequentially for about 10 seconds each, and eventually at time t1, the DC voltage becomes almost 0, and the line monitoring pulse Pa is generated multiple times at approximately 10 second intervals. .

In this invention, a detection circuit (9) that detects this line monitoring pulse Po, and a hold circuit (21) that holds the output state when the line monitoring pulse Pa is detected by this detection circuit (9). (23) and a system control circuit αω to which the outputs held by the hold circuits (21) and (23) are supplied.

[Effect]

When the line monitoring pulse is detected by the detection circuit (9), its detection output DET is held at one state by the hold circuits (21) (23), and this output DET is detected by the system control circuit aψ. The answering operation is stopped by the output of the control circuit αC, and preparation is made for the next incoming call.

〔Example〕

FIG. 1 shows an embodiment of the inventive device, where L and L2 are telephone lines.

A primary winding (1a) of a transformer (1) and a relay switch (2) are connected in series between the telephone lines LL and L2. The relay switch (2) is turned off while waiting for an incoming call. When a bell ringing signal as shown in FIG. 3A arrives while waiting for an incoming call, this bell ringing signal is supplied to the light emitting diode of the photocoupler (9) through the capacitor (7) and resistor (8). be done. This turns on the phototransistor of the photocoupler (9), and the output of the photocoupler (9) is the third one.
A signal as shown in the figure is obtained, and this is taken as the human input signal DET of the system control circuit αO). The system control circuit αω detects the incoming call based on this input signal, and sets its output signal, the relay control signal RL, to “0”. Since this control signal RL is supplied to the base of the PNP transistor (12) via the resistor (11), this transistor (12) is turned on, and the transistor is connected to the power supply terminal (13) from which a positive DC voltage can be obtained. Current flows to the relay (14) through (12), turning on the relay switch (2). Thereafter, under the control of the system control circuit α, for example, the tape recorder enters playback mode, and the output of the head (3) is passed through the playback amplifier (4) to the secondary winding of the transformer (1).
1b), which in turn connects the primary winding (
The reproduced signal is supplied to the telephone lines LL and L2 via 1b). Also, the tape recorder is put into recording mode,
A voice signal from the caller appearing on the telephone lines LL and L2 is supplied to a head (6) through a transformer (1), a recording amplifier (5), and recorded on a tape.

Also, the output RL of the system control circuit t1ψ is “
While the above-mentioned answering operation is performed in "0", the transistor (12) is on, and the transistor (12) is turned on through this.
A current is supplied to the base of the transistor (
15) is turned on, and a transistor (16) whose base is supplied with the collector output of this transistor (15) is turned off, allowing a holding operation of the detection output of the monitoring pulse Po, which will be described later.

The time constant circuit consisting of a resistor (17) and a capacitor (18) is used to prevent the influence of chattering when the relay (14) is turned on.
Immediately after turning on, line I, 1. A delay time is formed to prevent the hold circuit from operating until L2 is stabilized.

In this state, when the caller puts down the handset and goes on-hook, the line monitoring pulse Pa (FIG. 4A) is generated as described above after the caller goes on-hook. This pulse Pa is supplied to the light emitting diode of the photocoupler (9) through the capacitor (7) and resistor (8), which turns the phototransistor on and off, and the output DP of the photocoupler (9) is as shown in Figure 4B. It becomes like this. Then, when the phototransistor of the photocoupler (9) is turned on, the capacitor 'J- (20), to which charging current was supplied via the resistor (19) when it was off, is discharged through this phototransistor, and the transistor (
The base potential of the transistor (21) decreases, and the base potential of this transistor (21) decreases.
) is turned on. Then, the collector N current of this transistor (21) is connected to the transistor (2) through the resistor (22).
3), which turns on.

When this transistor (23) is turned on, the charging voltage of the capacitor (20) is changed to this transistor (23).
) will be discharged through the pulse P.

Transistors (21) and (23) remain active even after a pulse width period of
is turned on and that state is held. In other words, the transistors (21) and (23) constitute a hold circuit. The output of this hold circuit, that is, the transistor (
The collector output of 23) is "0" at this time.

Then, this hold output becomes the human input signal DET of the system control circuit aω, and when this is detected by the system control circuit αψ, an on-footer on the caller side is detected, and the output RL becomes “1” from rOJ.
will be launched on. Then, the transistor (12) is turned off, so that no current is supplied to the relay (14), the relay switch (2) is turned off, and the telephone lines LL, L2 to the tape recorder are cut off. and,
Also, the system control circuit αl stops the tape recorder or puts it into standby mode, and starts preparing for the next telephone call.

Note that when the transistor (12) is turned off, the base current is no longer supplied to the transistor (15), so this transistor (15) is turned off, and therefore the transistor (16) is turned on. Therefore, when the answering operation is not performed, that is, when waiting for an incoming call, this transistor (16) is on.
The transistor (23) of the hold circuit can be turned on, but no hold operation is performed. Therefore, even if an incoming call is received and a ringing signal is received while in this waiting state, a malfunction such as detecting on-hook will not occur. In other words, the signal DET is the system control circuit α
Until the incoming call is detected at 0 and the output signal RL is set to 0, it is not held by the hold circuit, resulting in a signal like that shown in FIG. 3B, and no malfunction occurs.

Note that the capacitor (24) inserted between the base of the hold transistor (23) and the ground is connected to the line L1. due to the time constant of the resistor (22). This capacitor is used to prevent the hold circuit, that is, the transistors (21) and (23) from performing a hold operation in which they are turned on due to noise in L2.

〔Effect of the invention〕

In this invention, after the caller goes on-hook, a detection signal for stopping the answering machine operation is obtained by using a line monitoring pulse that occurs multiple times. Detection is more reliable than when

Therefore, the next incoming call can be reliably and quickly prepared, allowing for efficient answering. In addition, unnecessary recordings after the caller goes on-hook are reduced, which improves tape usage efficiency and improves playback efficiency.
This is very convenient for users.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of an example of the main part of this invention device, and Fig. 2~
FIG. 4 is a diagram for explaining this. Ll and L2 are telephone lines, (2) is a switch for relay (14), (9) is a photocoupler that constitutes a monitoring pulse detection circuit, α is a system control circuit, (21) is a photocoupler that constitutes a monitoring pulse detection circuit;
) and (23) are transistors forming a hold circuit.

Claims (1)

[Claims] When the calling party goes on-hook, after periods of silence, busy tone, and silence occur at a constant DC voltage on the other party's line, line monitoring pulses occur multiple times at regular intervals when the DC voltage is approximately 0. It has a detection circuit, a hold circuit that holds the output state when the detection circuit detects the line monitoring pulse, and a system control circuit to which this held output is supplied, and the output of this system control circuit. An answering machine that stops the answering machine and prepares for the next incoming call.