JPH0238030B2 - - Google Patents

Description

[Detailed description of the invention]

(b) Industrial application field The present invention originates from a push-button telephone.
The present invention relates to a remote control circuit for an answering machine that allows DTMF (Dual Tone Multiple Frequency) signals to be used as remote control signals. (b) Prior Art There is an answering machine that connects to a telephone line and automatically records messages from callers. For example, Japanese Patent Publication No. 56-31786 describes such an answering machine that allows the owner to listen to messages from callers recorded while the owner is away on the telephone from outside the home. ing. In the answering machine described in the above publication, in order to listen to a message from a caller recorded while the owner is away from home, the owner first sends out a ringing signal and activates the own answering machine, Thereafter, it is necessary to send a remote control signal to rewind, fast forward, or play back the tape on the answering machine. (c) Problems to be Solved by the Invention Conventionally, the remote control signal used a signal oscillated by an oscillator, so the owner had to carry the oscillator. In view of these drawbacks, it is conceivable to use the aforementioned DTMF signal generated from a push-button telephone. However, the DTMF signal uses a signal in the audio frequency band. On the other hand, the timing to start remote control is during outgoing, when the answering machine starts up and transmits a message signal to the caller, and during incoming, when outgoing ends and the message signal from the caller is recorded. Although this is possible, in order to start remote control during incoming, it is necessary to wait until the message to the caller is finished, so normally remote control is started by sending a remote control signal during outgoing. Also, once the remote control has started and played, another remote control signal may be sent to fast forward or rewind the tape when there is no need to listen to that section. However, when a voice signal is being generated from an answering machine,
Even if a DTMF signal is transmitted, it is difficult to identify it, so a high-performance bandpass filter is required. The operations of the remote control include starting playback, switching between playback, rewinding, or fast forwarding, and since a remote control signal is used for each of these operations, it is necessary to provide the bandpass filter for each remote control signal, which increases costs. However, it is an object of the remote control circuit for an answering machine of the present invention to make it possible to use only one bandpass filter. (d) Means for Solving Problems The present invention provides an answering machine that plays back a recorded message signal and transmits it via a telephone line, or records a message signal that is transmitted via a telephone line, and a push-button telephone. transmitted over telephone lines
A pilot signal detection circuit including a high-pass filter and a low-pass filter that pass the DTMF signal, a narrow band band-pass filter that extracts one DTMF signal of the DTMF signals that have passed the high-pass filter and the low-pass filter as a pilot signal, and This is a remote control circuit for an answering machine, which is made up of a number of control circuits that are turned on by a signal and operated by a DTMF signal that has passed through a high-pass filter and a low-pass filter to control the answering machine. (e) Function The remote control circuit of the answering machine of the present invention has the above-described configuration. Now, when the owner wants to listen to a message recorded while he is away using the remote control, he sends a ringing signal to his own telephone and activates the telephone. When the telephone is activated, the answering machine is also activated and outgoing transmission of a message signal to the caller begins. For example, if the owner presses the "#" button on a pushbutton telephone in such a state, the signal will be 941Hz.
A DTMF signal having a frequency of 1447Hz is generated. The DTMF signal is transmitted through a telephone line and detected by a high-pass filter and a low-pass filter, and then applied to a pilot signal detection circuit to detect a pilot signal. The pilot signal mutes the message signal generated by the answering machine and applied to the telephone line, and puts the control circuit into operation. Therefore, when you press the "1" button, DTMF signals of 1209Hz and 697Hz are generated,
After the signal is detected by a high-pass filter and a low-pass filter, it is fed to one of the control circuits,
The control circuit is operated to put the telephone answering machine into a playback state, and the message recorded while the user is away is played back and transmitted via the telephone line. Similarly, pressing other pushbuttons on a pushbutton telephone can be used to rewind or fast forward by remote control. (f) Embodiments The remote control circuit of the answering machine of the present invention will be described in detail according to embodiments. 1 is a line transformer connected to telephone lines L ₁ and L ₂ ,
A line amplifier circuit 2, a high pass filter 3 and a low pass filter 4 that pass the DTMF signal are connected to the output side. Reference numeral 5 denotes an answering machine connected to the line amplification circuit, which includes a first tape recorder that is activated by a ringing signal applied through the line amplification circuit 2 and transmits a message to the caller, as is generally known; When the message to the caller is finished, it automatically enters the recording state, and has a second tape recorder etc. that records the message from the caller, and the second tape recorder can be put into the playback state, rewind or fast forward with the plunger described later. state. 6 is a muting transistor for muting the message signal from the answering machine 5; 7 is a pilot signal detection circuit; bandpass filters 8, 9 with excellent frequency selection characteristics;
cycle identification circuits 10 and 11 connected to the circuit for identifying a signal with a predetermined cycle; the cycle identification circuit 10;
AND gate circuit 1 that gates signals from 11
2 and a timer circuit 13. The bandpass filters 8 and 9 have a pass frequency band, for example, in order to pass the sharp signal among the DTMF signals.
941Hz and 1447Hz, and of course the period identification circuits 10 and 1 are connected to the bandpass filters 8 and 9.
1 also makes it possible to identify the DTMF signal of the above frequency. Further, when the timer 13 receives a signal from the AND gate circuit 21, it generates a pilot signal for 8 seconds. 14,15,1
6 is a control circuit, which includes zero crossing detection circuits 17 and 18 commonly connected to the high-pass filter 3 and low-pass filter 4, respectively, and these zero crossing detection circuits 17 and 1.
switches 19 and 20 connected to the zero crossing detection circuit 17 and turned on and off by the pilot signal; period identification circuits 21, 22, and 23 connected to the zero crossing detection circuit 17, respectively;
Period identification circuit 2 connected to zero crossing detection circuit 18
4. AND gate circuits 25, 26, 27 which AND-gate each signal from the period identification circuits 21, 22, 23 and the signal from the period identification circuit 24, and operate at the output paths of the AND gate circuits 25, 26, 27. The plunger circuits 28, 29, and 30 each have a plunger. As an example, the cycle identification circuit 24 detects "1" to "1" of a push-button telephone.
It is designed to identify a signal with a common frequency of 697Hz of the DTMF signal generated when the "3" button is pressed, and the period identification circuits 21, 22, 23 are
The other frequency of DTMF signal is 1209Hz, 1336Hz and
1447Hz can be identified individually. Further, the plunger circuits 28, 29, and 30 each have a plunger for placing the answering machine 5 in a playback state, a rewind state, or a fast forward state. Next, the operation of the remote control circuit of the answering machine of the present invention will be explained. First, when a pushbutton telephone presses each pushbutton, it emits a DTMF signal (Dual Tone Multiple) that is a mixture of two frequencies determined by each pushbutton.
Frequency signal) is generated. That is,

[Table] The present invention utilizes this DTMF signal as a remote control signal. To listen to messages recorded while the owner is away by phone from outside the home, a ring signal is sent to the owner's phone. The ring signal is a telephone line
The signal is supplied to the line amplifier circuit 2 via the line transformer 1 by L ₁ and L ₂ to start up the telephone. Then, the answering machine is also activated, and the message to be transmitted to the caller is reproduced from the first tape recorder. The message passes through a line amplifier circuit 2 and a line transformer 1 and enters telephone lines L ₁ and L ₂ . Therefore, the owner can confirm that his answering machine 5 has been activated, and when the owner first presses the "#" button on the pushbutton telephone, a DTMF signal with frequencies of 941Hz and 1477Hz is generated. oscillates. That DTMF
The signal is supplied to a high pass filter 3 and a low pass filter 4 via a line transformer 1. Said
The 1477Hz component of the DTMF signal is passed through high pass filter 3.
After passing through, it is supplied to the band pass filter 9,
There, the signal is filtered and supplied to the period identification circuit 11, and only the signal of that component is detected. or
The 941 Hz component of the DTMF signal is similarly supplied from the low-pass filter 4 to the band-pass filter 8 to the cycle identification circuit 9 and detected, but at this time the message signal is reproduced by the answering machine 5. Since the frequency of the message signal includes the same frequency component as the DTMF signal, it is also applied to the high-pass filter 3, low-pass filter 4, etc., making it difficult to distinguish between the message signal and the DTMF signal. Therefore, in the present invention, bandpass filters 8 and 9 having good filter characteristics are used so that the DTMF signal can be reliably filtered. When a signal of 50 milliseconds or more is applied to the AND gate circuit 12 from both the cycle identification circuits 10 and 11, the timer 13 is activated by the signal output from the AND gate circuit 12 and generates a pilot signal for 8 seconds. The pilot signal turns on the muting transistor 6 to mute the message signal generated from the answering machine 5 so that it is not supplied to the high-pass filter 3 and low-pass filter 4 via the line amplifier circuit 2, and also switches 19, 20. is turned on to make the control circuits 14, 15, and 16 operational. When the owner presses the "1" button in this state, a DTMF signal with frequencies of 697Hz and 1209Hz is generated, which is transmitted to the high-pass filter 3 and low-pass filter 4 via the telephone lines L ₁ and L ₂ and the line transformer 1. Supplied. Since the switches 19 and 20 are on, the DTMF signal that has passed the high pass filter 3 and the low pass filter 4 is applied to the zero crossing detection circuits 17 and 18, and the zero crossing of the DTMF signal is detected, and the period identification circuits 21 and 24 is applied to At this time, since the output of the answering machine 5 is muted by the muting transistor 6, it is not applied to the high-pass filter 3 or the high-pass filter 4.
DTMF signals can be detected reliably. The 1209Hz component of the DTMF signal is identified by a period identification circuit 21,
The 697 Hz component is also identified by period identification path 24 and applied to AND gate circuit 25 to produce respective outputs.
As a result, an output is generated from the AND gate circuit 25, the reproducing plunger of the plunger circuit 28 is energized, and the second tape recorder of the answering machine 5 is put into the reproducing state, so that the message from the caller recorded on the second tape recorder is Play. At this time, since the set time determined by the timer 13 has already elapsed, the pilot signal has disappeared and the muting transistor 6 has been turned off. It is supplied and transmitted to lines L ₁ and L ₂ .
When the owner wishes to listen again to the transmitted message, he presses the "#" button to transmit the DTMF signal in the same manner as described above, and the pilot signal detection circuit 7 generates a pilot signal, turns on the muting transistor 6, and , turn on switches 19 and 20. After that, press the "2" button to generate a DTMF signal having 697Hz and 1336Hz. Then, a signal is generated from the cycle identification circuits 22 and 24, which is applied to the AND gate circuit 26 of the control circuit 15 to generate an output, and the signal is output from the plunger circuit 2.
9 is operated to operate the rewind plunger, and the telephone answering machine 5 is placed in the rewind state. If the "1" push button is pressed when the tape has been rewound to a predetermined location, the playback state is resumed in the same manner as described above. By pressing the "2" push button during playback using the remote control, the telephone answering machine 5 can be placed in a fast-forward state. That is, by pressing the "#" push button to generate a pilot signal from the pilot signal detection circuit 7, and pressing the "2" push button with the muting transistor 6 turned off and switches 19 and 20 turned on. did
When the DTMF signal is transmitted, the plunger circuit 30 of the control circuit 16 operates, and the answering machine 5 is placed in a fast-forward state. When the message is played back by remote control and left for a while after passing the recorded message, the answering machine 5 is turned off, the telephone is turned off, and the call is ended. (G) Effects of the Invention As described above, the remote control circuit of the answering machine of the present invention is generated by first pressing the push button of the push button telephone.
One of the DTMF signals is extracted as a pilot signal by a pilot signal detection circuit having a bandpass filter with excellent filter characteristics, and the output of the answering machine is temporarily muted using the pilot signal, and the answering machine is put into a playback state. Or, since each control circuit for rewinding or fast forwarding is enabled, the audio signal and
A bandpass filter with excellent selection characteristics required to distinguish between DTMF signals can be used only in the pilot signal detection circuit, and does not need to be used in each of the control circuits. Since it is composed of a common filter that passes a common frequency signal and individual filters that pass individual frequency signals of the DTMF signal, the number of filters can be reduced, and a remote control circuit with excellent performance can be provided at a low cost.
If there is a possibility that someone else may eavesdrop on the data by remote control operation, the control circuit may be operated using two or more types of DTMF signals.

[Brief explanation of drawings]

The figure is a block diagram of the control circuit of the answering machine of the present invention. 3... High pass filter, 4... Low pass filter, 5... Answering machine, 6... Muting transistor, 7... Pilot signal detection circuit, 8, 9... Band pass filter, 14, 1
5, 16... control circuit, 19, 20... switch, 28, 29, 30... plunger circuit.

Claims (1)

[Claims] 1. A remote controller that reproduces a prerecorded message signal and transmits it via a telephone line, or records a message signal transmitted via a telephone line, and transmits the recorded message signal via the telephone line. In an answering machine that reproduces a signal and transmits the reproduced message signal via a telephone line, DTMF is a mixture of two-frequency signals generated by a push-button telephone.
Among the signals - a pilot signal detection circuit having a narrowband bandpass filter with a steep filter characteristic that passes the DTMF signal, a timer operated by the pilot signal detected by the pilot signal detection circuit, and a timer operated by the pilot signal detected by the pilot signal detection circuit; a muting transistor that is operated to mute the output of the answering machine; a common filter that is operated by the timer, each having a slow filter characteristic, and passing a common frequency signal of the DTMF signals other than the -DTMF signal; and a common filter and an individual frequency filter; An individual filter that passes the signal, an AND gate circuit that AND gates the DTMF signals that have passed through the common filter and the individual filters, and an answering machine that is excited by the signals that have passed through these AND gate circuits to operate the answering machine. A remote control circuit for an answering machine consisting of a plunger and a remote control circuit for controlling an answering machine.