JPH036057Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a signal transmission circuit for a telephone device, and more particularly to a signal transmission circuit for a telephone device that transmits signals between a telephone device main body and a multifunction circuit.

Conventional technology Conventionally, in addition to a call function with the other party, there is also an answering machine recording function, a simultaneous recording function to record the contents of the call, and a speaker call function that allows multiple people to listen at the same time by playing the contents of the call from a speaker instead of a handset. There is a telephone device that includes a plurality of circuits (hereinafter referred to as "multifunctional circuits") each having a multifunction circuit.

In such a telephone device, it is stipulated that the power line that supplies power voltage to the multifunctional circuit and the telephone line connected to the exchange and that transmits telephone signals are insulated to prevent noise. For this reason, conventional telephone devices have been configured such that only the signal system is coupled using, for example, a transformer as a signal transmission circuit between the telephone device main body and the multifunction circuit.

FIG. 2 shows a block system diagram of an example of a conventional telephone device. In the figure, a telephone device 1 includes a ringer circuit 2, a piezoelectric buzzer 3, a speech network 4, a dialer circuit 5, a numeric keypad 6, a handset 7, etc., which are the minimum configuration necessary only for telephone calls (corresponding to the telephone device itself). In addition to the configuration shown in FIG. Here, the speech network 4 is composed of a 2-wire to 4-wire conversion circuit, a microphone amplifier, and a sidetone circuit for allowing the owner of the telephone device 1 to also hear the sound on the receiver in order to eliminate unnaturalness of the call. . Further, the AC adapter 12 converts the 100V AC household power supply voltage supplied through the plug 13 into a predetermined DC voltage, and supplies the DC voltage to the speaker communication circuit 8 and the recording/reproducing circuit 9, respectively. moreover,
In FIG. 2, 14 to 17 indicate signal system transformers, among which transformer 14 is a call signal system, transformer 15 is a dial signal system, and transformer 1 is a dial signal system.
Reference numeral 6 is inserted into the playback signal system, and transformer 17 is inserted into the recording signal system. These transformers 14
.about.17, the speech network 4 and dialer circuit 5 are DC-insulated from the speaker communication circuit 8 and the recording/reproducing circuit 9.

One end of the primary winding 14a of the transformer 14 is connected to one end of a current source _I1 via a capacitor _C1 ,
The other end of the primary winding 14a and the other end of the current source _I1 are connected, respectively. Further, when the recording/reproducing circuit 9 is operated for recording, a telephone call signal coming through the transformer 17 or an owner's voice signal supplied from the microphone 10 is transferred from the recording/reproducing circuit 9 to the magnetic head H. recorded on magnetic tape. On the other hand, during playback, the playback audio signal played from the magnetic tape is supplied from the recording and playback circuit 9 to the handset 7 via the transformer 16 and is outputted, or alternatively, the playback audio signal from the recording and playback circuit 9 is sent to the speaker 11.
is supplied and pronounced.

On the other hand, the call signal input terminals 18a and 18b are connected to an exchange (both not shown) via a call line, and a DC voltage of about 48V is normally applied thereto. These input terminals 18a, 18b
A varistor 19 is provided between the terminals and absorbs a high voltage of about 480 V generated between the two terminals due to lightning, for example, and prevents this high voltage from affecting the telephone device 1. Further, the polarity circuit 20 is connected to its primary side (i.e., input terminals 20a, 20b
This circuit is provided to make the polarity of the output signal on the secondary side (that is, the output terminal 20c, 20d side) constant regardless of the polarity of the input signal on the secondary side (output terminal 20c, 20d side).

Furthermore, the on/off switches 21 and 22 are switches that are turned on or off in conjunction with the hook switch 23, respectively. Normally, in the initial standby state when the handset 7 is placed on the hook, the input terminal 18a is connected to the switch 21 and the capacitor C. ₂ to the ringer circuit 2, while the switch 22 is turned off. Further, the open/close switch 24 and the changeover switch 25 are switches that are switched in conjunction with the speaker call switch 26, and in the initial standby state, the switch 24 is off, while the switch 25
is connected to the terminal 25a side.

In the above configuration, when a call is received from the other party, a calling signal is supplied from the input terminals 18a and 18b to the ringer circuit 2 via the switch 21, etc., the piezoelectric buzzer 3 is operated, and a calling tone is generated. be done. As a result, when the owner removes the handset 7 from the hook, the switch 21 is turned off and the ringing tone stops, while the switch 22 is turned on.
The output terminal 20d of the polarity switch 20 is connected to the speech network 4 via switches 22 and 25.
connected to.

In this way, the output terminal 20 of the polarity circuit 20
Since a dialer circuit 5 and a speech network 4 or a current source I ₁ and a speaker communication circuit 8, which will be described later, are connected to the c and 20d sides, respectively, the 48V DC voltage supplied to the input terminals 20a and 20b is as follows. The polarity was converted and attenuated as shown in
Output terminals 20c, 20 as a DC voltage of about 10V
It is output from d. On the other hand, compared to this DC voltage of about 10V, the voice signal level of a call number is about 0.7V.
Since this is extremely small, the audio signal is output without being rectified. In this way, the telephone device 1 becomes ready for communication.

Further, when the speaker call switch 26 is operated to make a call using the speaker 11, the switch 24 is turned on, while the switch 25 is turned on to connect the terminal 2.
5b side, and the output terminal 20d of the polarity switch 20 is connected to the switch 24 (or switch 22),
It is connected to one end of the primary winding of the transformer 14 via a switch 25 or the like. In this way, the contents of the call are sounded by the speaker 11, and the owner can talk to the other party through the microphone 10 and the speaker 11.

Further, when the owner puts the handset 7 on the hook after the end of the call, the switch 21 is turned on, while the switch 22 is turned off, and the telephone device 1 returns to its initial standby state.

Problems to be Solved by the Invention However, the dimensions of the transformers 14 to 17 used in the conventional telephone device 1 described above are large in terms of transmission characteristics, which hinders miniaturization of the device. There were also problems such as increased costs.

Therefore, an object of the present invention is to provide a signal transmission circuit for a telephone device that solves the above-mentioned problems by using a signal transmission circuit consisting of a light-emitting element, a light-receiving element, and a level adjustment means instead of the above-mentioned transformer. do.

Means for Solving the Problems The signal transmission circuit of the telephone device according to the present invention includes a light-emitting element that emits light in response to a voice signal or dial signal supplied from the telephone device, and a light-emitting element that emits light in response to the light emitted from the light-emitting element. Equipped with a photocoupler consisting of a light receiving element that generates a signal and an ALC circuit that always outputs the output signal of the photocoupler to the speaker communication circuit at a constant signal level, the ALC circuit absorbs variations in photoelectric conversion in the photocoupler. composition.

Function: The voice signal or dial signal from the telephone device is converted into light by the light-emitting element and the light-receiving element, and then converted into an electric signal again, so that there is electrical insulation between the telephone device and the multi-function circuit. be done.

Furthermore, if a light emitting diode and a phototransistor are selected as the light emitting element and the light receiving element, respectively, and an electronic circuit that can be integrated into an IC is selected as the level adjustment means, the signal transmission circuit made of these will be smaller in size than the transformer. Therefore, the telephone device can be miniaturized.

Furthermore, since an ALC circuit is provided at the output of the photocoupler, variations in photoelectric conversion gain in the photocoupler can be automatically absorbed, allowing dial signals to be transmitted without transmission variations.

Embodiment FIG. 1 shows a block system diagram of an embodiment of a signal transmission circuit of a telephone device according to the present invention. In the figure, the same components as in FIG. 2 are denoted by the same reference numerals, and the explanation thereof will be omitted. In the block system shown in FIG. 1, the ringer circuit 2, piezoelectric buzzer 3, speech network 4, handset 7, recording and reproducing circuit 9, etc. shown in FIG. 2 are not shown. In addition, in FIG. 1, the polarity circuit 27 is the polarity circuit 20.
It has the same function as .

In this embodiment, the transformer 1 is inserted and connected between the dialer circuit 5 and the speaker communication circuit 8.
Instead of 5, an IC photocoupler 30 (for example, a model manufactured by Sharp Co., Ltd.
A photocoupler such as PC817) is connected to an ALC circuit consisting of an amplifier 31, a rectifier circuit 32, and a variable resistor 33, which corresponds to the level adjustment means.

Input terminals 27a and 27b of the polarity circuit 27 are connected to the call signal input terminals 18a and 18b, respectively, while an output terminal 27c is connected to the input terminal 5a of the dialer circuit 5, one end of the primary winding 14a of the transformer 14, and the are respectively connected to the speech network 4, and the output terminal 27d is connected to the switch 2.
2 and 24 in parallel to the switch 25. The terminal 25a of the switch 25 is connected to the speech network 4, and the terminal 25b is connected to the other end of the primary winding 14a of the transformer 14 via the capacitor _C1 as described above. In addition, the current source
_I1 is the connection point between the terminal 25b of the switch 25 and the capacitor _C1 , and the output terminal 27c of the polarity circuit 27.
Inserted and connected in between. The above switch 22, 2
The common connection point of each of 4 and 25 is the dialer circuit 5.
The LED 28 is connected to the input terminal 5b of the LED 28 via the constant current circuit 34 and the resistor R.

The constant current circuit 34 and the resistor R are connected to the polarity circuit 2
Since the output DC voltage of 7 varies between 10 and 4V and is not stable, it is provided to convert this into a stable DC voltage and supply it to the LED 28.

On the other hand, the output terminal 5c of the dialer circuit 5 is connected to the anode of the LED 28 via a capacitor _C3 , and the output terminal 5d is connected to the cathode of the LED 28. On the other hand, the collector of the phototransistor 29 is connected to the speaker communication circuit 8 via the amplifier 31.
The emitter is connected to the input terminal 8b of the speaker communication circuit 8. Further, the output end of the amplifier 31 is connected to its input end via a rectifier circuit 32 and a variable resistor 33.

To explain the operation of the circuit of the present invention when making a call to the other party in the above configuration, first, when the owner removes the handset 7 from the hook, the hook switch 23 is operated and the switch 21 is turned off, while the switch 22 is turned off. Turns on. At this time,
When the owner operates the speaker call switch 26 to turn on the switch 24 and also switches the switch 25 to the terminal 25b side, the output DC voltage of the polarity circuit 27 is supplied to the dialer circuit, and the constant current circuit LED through 34 and resistor R
A current flows through 28.

After that, when you press the other party's phone number on the numeric keypad 6, a dial signal (Dual Tone Multi Frequency signal) consisting of multiple frequency signals is generated, which connects the dialer circuit 5 and the capacitor _C3.
The light is supplied to the LED 28 through. The LED 28 performs a dimming operation depending on the frequency of the incoming dial signal. In this way, the dial signal is converted into an optical signal by the LED 28.

This dial signal converted into an optical signal is supplied to the base of the phototransistor 29. The phototransistor 29 turns on and off depending on the frequency of the dial signal, and after the dial signal is converted into an electrical signal again, the amplifier 31
is supplied to

By the way, the dial signal needs to be transmitted at a constant level. For this reason, amplifier 3
A part of the output signal of the amplifier 31 is supplied to a variable resistor 33 via a rectifier circuit 32 to control its resistance value, thereby keeping the signal level of the amplifier 31 constant.

The dial signal, which has been set at a constant level in this manner, is supplied from the amplifier 31 to the speaker communication circuit 8, and is output from the speaker 11.

Note that the photocoupler 30 and the ALC amplifier can both be constructed in the same IC chip, thereby further reducing the size of the circuit of the present invention. Further, in this embodiment, a circuit consisting of a photocoupler 30 and an ALC amplifier is applied in place of the transformer 15 for the dial signal system, but this circuit can be used as is for the transformers 14 and 1 for the normal audio signal system.
5 and 16, there are many variations in the signal transmission of the photocoupler 30, which poses a problem in actual use. Therefore, it is necessary to select a photocoupler with good linearity, and to use an automatic gain control circuit (AGC circuit).
By using the audio signal system transformer 1
The present invention can be applied in place of 4, 15, and 16. Furthermore, it goes without saying that the circuit of the present invention can be applied to other dial-type telephone devices.

Note that the present invention is not limited to this embodiment, and the LED 28, phototransistor 29, and
Of course, the ALC circuit may also be replaced by other light emitting elements, light receiving elements, and level adjustment means.

Effects of the invention As described above, according to the invention, it is possible to convert an electrical signal into an optical signal and then transmit the signal.
Therefore, the input and output of the signal transmission circuit can be electrically isolated, and the ALC circuit can keep the signal output level constant and transmit the dial signal without transmission variation. It has the advantage that the telephone device can be made smaller and the cost can be reduced by incorporating each adjustment means into an IC.

[Brief explanation of the drawing]

FIG. 1 is a block system diagram showing one embodiment of a signal transmission circuit of a telephone device according to the present invention, and FIG. 2 is a block system diagram showing an example of a conventional telephone device. 5...Dialer circuit, 6...Numeric keypad, 8...
...Speaker communication circuit, 10...Microphone, 1
1... Speaker, 14... Transformer, 27... Polar circuit, 28... Light emitting diode (LED), 29
...Phototransistor, 30...Photocoupler, 31...Amplifier, 32...Rectifier circuit, 33...
...Variable resistor, 34... Constant current circuit, C ₃ ... Capacitor.

Claims (1)

[Claims for Utility Model Registration] Signal transmission of a telephone device that performs signal transmission between a telephone device and a plurality of multi-function circuits that perform recording and reproduction of voice signals or dial signals from the telephone device, or generate sounds through speakers, etc. In the circuit, a photocoupler comprising a light emitting element that emits light in response to the voice signal or dial signal supplied from the telephone device, and a light receiving element that generates a signal corresponding to the light emitted from the light emitting element; and the photocoupler. A signal transmission circuit for a telephone device, characterized in that the ALC circuit absorbs variations in photoelectric conversion in the photocoupler by using the ALC circuit, which outputs the output signal of the above at a constant signal level to the speaker communication circuit at all times. .