JPS6351624B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a circuit configuration of a tone ringer circuit for a telephone, which is suitable for making the ringer tone multi-tone and converting the circuit into a single chip IC.

<Prior art> Conventional tone ringer circuits have a configuration using an IC self-excited oscillator or two or three circuits using C-MOS.
The CR astable multivibrator allows two types of high frequencies (around 500 to 1500 Hz) to be transmitted to low frequencies (5 to 15 Hz).
It had a configuration in which a ringing sound signal generation circuit that alternately generates a ringing sound signal (around Hz) and a drive circuit made up of individual transistors were connected in parallel.

These tone ringer circuits require a plurality of capacitors or resistors to be switched in order to vary the oscillation frequency and produce a multitone ringer sound, which has the disadvantage of increasing the number of individual components. In addition, the circuit efficiency of the former IC self-excited oscillator is as low as 50% even at the maximum theoretical efficiency, and in the latter case, even if the circuit efficiency of the drive circuit alone is theoretically 100%, the current flowing to the digital circuit for ringer sound generation I _psc The circuit efficiency η para is determined by the ratio of the current I _put flowing to the drive circuit that drives the sounder, and the circuit efficiency η _para is expressed by the following formula.

η _para = I _put / (I _psc + I _OUt ) = 1 - I _psc / I _sup Typically supply current I _sup = 6 mA, supply voltage V _sup =
For example, in the circuit block configuration shown in a of Figure 1A, the minimum voltage V _psc and current I _psc required for the digital circuit are approximately 1 V and 1 mA, respectively, so the drive circuit and digital circuit Since currents of 5 mA and 1 mA are supplied, respectively, the circuit efficiency is as follows.

η _1para = 1-I _psc /I _sup = 1-1/6≒0.83 Also, if multiple telephones, for example three telephones, are connected to one telephone line, and the power supply current I _sup per telephone becomes 3 mA. , the circuit ratio in this case is as follows.

η _2para =1-1/3≈0.67 As described above, the circuit efficiency of the conventional parallel-connected ringer circuit has a drawback that the circuit efficiency of the ringer circuit decreases as the number of telephones connected to one telephone line increases.
Furthermore, adding a resonance prevention circuit or the like increases the number of individual components, which has the drawback of leading to an increase in price.

In addition, in order to integrate these tone ringer circuits into ICs, the former has the drawback of requiring high withstand voltage, while the latter requires a C-type with low current drive capability.
MOS products have the disadvantage that it is difficult to incorporate the drive circuit that drives the sounder (sound emitter) into a single chip IC.

<Objective of the Invention> In order to eliminate these drawbacks, the present invention provides multi-tone ringtones by digitally processing the generation of ringtone signals, as well as a digital circuit that generates ringtone signals and amplifies the signals. The present invention provides a circuit configuration that enables integration into a single chip IC with a linear circuit such as a drive circuit that drives a sounder, and also prevents a decrease in circuit efficiency due to a decrease in power supply current.The drawings are explained in detail below. do.

<First Embodiment> FIG. 1B shows an embodiment of the present invention. input terminal
L ₁ and L ₂ are connected to the station through the subscriber line when the telephone is waiting for an incoming call, and when an incoming call is received, a calling signal, e.g. 75 Vrms, 16 Hz, superimposed on a DC voltage, e.g. 48 V, is applied between the input terminals L ₁ and L ₂ . applied. This call signal passes through the DC blocking capacitor 11 and is rectified in both waves by diodes D ₁ to _{D 4} , and the double-wave rectified output is sent to the capacitor 1.
2, the power supply terminal L ₃ is smoothed by DC voltage with less pulsating component as shown in curve 13 of FIG.
-L applied between ₄ . The voltage at the power supply terminal L ₄ is input to the threshold circuit 15 through the variable resistor 14 . The threshold circuit 15 is a circuit that detects whether the voltage between the power supply terminals L ₃ and L ₄ exceeds a level preset by the variable resistor 14 .

Immediately after receiving the call signal, the digital circuit 16 is not operating, and during this time, even if the digital circuit 16 starts operating as described later, the voltage applied between the power supply terminals L ₃ and L ₄ remains unchanged. is the ringing start voltage V _ON preset by the variable resistor 14.
Therefore, the threshold circuit 15 makes the transistor switch 19 non-conductive through the AND gate 18 in the output control circuit 17. Since the transistor switch 19 is non-conductive, a small current flowing through the threshold circuit 15 connected in series with the transistor switch 19 is as follows.
The current becomes the base current of the transistor switch 21 and makes the transistor switch 21 conductive. When the transistor switch 21 becomes conductive, a DC current starts to flow between the power supply terminals L ₃ -L ₄ through the DC load resistor 22 , the transistor switch 21 zener element 23 , and the constant voltage circuit 24 when there is no sound, and the operating voltage of the digital circuit 16 increases. A stabilizing capacitor 25 is connected in parallel between the constant voltage circuit 24, the power supply terminal _L3 , and the series connection terminal _L5 , and this capacitor 25 is charged.

The voltage across the capacitor 25 provides an operating voltage to the digital circuit 16, and when the charging voltage of the capacitor 25 increases and the constant voltage circuit 24 exhibits constant voltage characteristics, the digital circuit 16 starts operating. Main oscillation circuit 2 using crystal oscillator 26
7 generates a reference clock, and this reference clock is frequency-divided by a variable frequency divider circuit 28.
from which the digital signal that is the basis of the ringer sound is generated. The output control circuit 17, the main oscillation circuit 27, and the variable frequency dividing circuit 28 constitute the digital circuit 16.

A trigger type flip-flop 29 is used at the final stage of the variable frequency divider circuit 28, and an opposite phase ringer tone signal with a duty of 50:50 is generated at its Q and output terminals. These Q and output terminal signals are input to AND gates 31 and 32 in the output control circuit 17, respectively, and the output of the threshold circuit 15 is given to the other input of the AND gates 31 and 32.

When the voltage applied between the power supply terminals L ₃ and L ₄ exceeds the ringing start voltage V _ON , the threshold circuit 15 opens the AND gates 31 and 32, and the Q output of the flip-flop 29 is output from the amplifier 3 of the BTL drive circuit 33.
4 and 35, respectively, and amplifiers 34 and 35.
The sounder 36 connected between both outputs of starts sounding. At the same time, the threshold circuit 15 makes the transistor switch 19 conductive through the AND gate 18 of the output control circuit 17, so that the voltage between the base and emitter of the transistor switch 21 becomes zero, and the voltage between the base and emitter of the transistor switch 21 becomes zero.
becomes non-conductive, and the DC current that was flowing through the load circuit 37 during non-sounding, that is, the DC load resistor 22, transistor switch 21, and Zener element 23 during non-sounding, begins to flow through the BTL drive circuit 33 to the constant voltage circuit 24. This current becomes an AC output current to the sounder 36. In other words, the load circuit 37 when no noise occurs.
are connected in parallel between the drive circuit 33, the power supply terminal _L4 , and the series connection terminal _L5 , and the drive circuit 33 is connected in series between the digital circuit 16 and the power supply terminals _L3 , _L4 via the series connection terminal _L5 . has been done.

The power supply current from the station to the tone ringer circuit is DC blocking capacitor 11 (generally the capacitance value is 0.9μF, 16Hz
It shows an impedance of about 11KΩ for a calling signal. ) has a large impedance, so fluctuations due to the distance from the telephone office or the direct current resistance of the ringer circuit are small and almost constant. Therefore, the DC resistance of the ringer circuit determines the voltage applied to the ringer circuit, and the larger the DC resistance, the higher the applied voltage.
The DC resistance of the ringer circuit is determined by the non-sound load resistor 22 when there is no sound, and the DC resistance of the drive circuit (impedance of the sounder 36) when there is sound.
Depends on.

On the other hand, the ringing start voltage V _po is the ringing stop voltage V _pff
Therefore, if the resistance value of the non-sound load resistor 22 is larger than the DC resistance value of the drive circuit, the applied voltage will start to ring when the applied voltage rises and will drop, and when it falls below the ringing stop voltage, the ring will start. stops. However, when the ringing stops, the applied voltage increases, so the ringing starts again.

If the resistance value of the non-sounding load resistor is greater than the DC resistance value of the drive circuit, there is a possibility that the ringing may continue, so the resistance value of the non-sounding load resistor is smaller than the DC resistance value of the drive circuit. It is necessary to set it.

Further, the threshold voltage as the terminal voltage of the threshold circuit 15 is V _TH , the voltage of the constant voltage circuit 24 is V _R ,
Letting the Zener voltage of the Zener element 23 be V _Z ,
If the voltage between the base and emitter of the transistor switch 21 is ignored, the transistor switch 19 is non-conductive before the ringing starts, so the ringing start voltage
V _ON is expressed by the following formula.

V _ON =V _TH +V _R +V _Z On the other hand, before the ringing stops, transistor switch 19
is conductive, and if the saturation voltage of the transistor switch 19 is ignored, the ringing stop voltage V _OFF is expressed by the following equation.

V _OFF = V _TH + V _R From the above two equations, the following relationship is obtained.

V _ON = V _OFF + V _Z Therefore, the Zener V _Z of the Zener element 23 is
By setting the amplitude voltage to be equal to or higher than the amplitude voltage of the pulsating flow component between the power supply terminals L ₃ and L ₄ , it is possible to avoid a situation where the output of the threshold circuit 15 is repeatedly inverted due to the pulsating flow component and the ringing is intermittent. . Threshold circuit 1
5. The transistor switch 19 constitutes an erroneous ringing prevention circuit 20. Furthermore, the ringing start voltage V _ON
The voltage must be set to be higher than the voltage applied between the power supply terminals _L3 and _L4 during hooking operations or dial pulses from the telephone with the built-in circuit shown in Figure 1B or from another branch-connected telephone. Ba,
Erroneous ringing due to hooking or dial pulse can be prevented. In other words, for example, due to the dial pulse from the branch telephone, the voltage between the power supply terminals L ₃ - L ₄ becomes curve 38 in Figure 2. From this, the ringing start voltage V _ON is increased, while the voltage from the terminal (not shown) is increased. By varying the frequency dividing number of the variable frequency dividing circuit 28 using digital information, it is possible to obtain ringing sounds of various frequencies. That is, by taking out one terminal from the middle position of the variable frequency dividing circuit 28, two types of frequencies can be switched. By taking out two terminals, you can switch between up to four types of frequencies.

According to this invention, as shown in b of FIG. 1A,
The circuit efficiency of the series-connected ringer circuit is determined by the ratio of the voltage V _psc applied to the digital circuit and the voltage V _put applied to the driver circuit, and the circuit efficiency η _seri is expressed by the following equation.

η _seri = V _put / (V _psc + V _put ) = 1-V _psc / V _sup However, the drive circuit that drives the sounder is an analog circuit that needs to handle relatively large currents and voltages, and generates a ringing sound. Digital circuits operate with relatively small currents and voltages. Bipolar linear process is an IC process that can accommodate a mixture of analog and digital circuits.
Injection Logic).

Minimum required voltage for digital circuit in this case
V _psc and current I _psc are approximately 1 V and 1 mA, respectively. Generally supply current I _sup =6mA, supply voltage V _sup
= about 19V, and the circuit efficiency is as follows.

η _seri = 1-1/19≒0.95 On the other hand, in the case of a parallel-connected ringer circuit, the circuit efficiency is η _para = 1-1/6≒0.83, and the circuit efficiency η _seri of a series-connected ringer circuit is The circuit efficiency η _para of the ringer circuit is improved.

Therefore, even if a plurality of telephones are connected to one telephone line and the supply current and voltage per telephone are reduced, the decrease in the circuit efficiency η _seri of each telephone can be suppressed to a small level.

In this way, the series-connected ringer circuit of the present invention can greatly reduce the decrease in circuit efficiency due to connection conditions, and the circuit efficiency of the conventional parallel-connected ringer circuit described above decreases as the power supply current decreases. It is possible to prevent the shortcoming of a sudden drop in power, and to stably and efficiently convert the limited station power supply into ring volume.

<Second Embodiment> Next, Fig. 3 shows an embodiment in which a volume control function is added to the circuit shown in the embodiment of Fig. 1, and the basic part of the circuit is the same as that in Fig. 1. The same parts are given the same symbols and the explanation will be omitted. In this embodiment, a variable resistor 39 is connected in series with the sounder 36, and a Zener element 41 is connected in parallel with the BTL drive circuit 33. Volume adjustment is performed as follows. Since the output voltage of the BTL drive circuit 33 is divided by the sounder 36 and the variable resistor 39, the volume can be easily reduced by simply increasing the resistance value of the variable resistor 39.
However, if the Zener element 41 is not provided, an increase in the resistance value of the variable resistor 39 will lead to an increase in the DC resistance of the entire tone ringer circuit, and an increase in the supply voltage between the power supply terminals L ₃ and L ₄ . This results in a decrease in the supply current. That is, the Zener element 41 is connected to the power supply terminal L ₃ due to the increase in DC resistance.
This suppresses the increase in the power supply voltage between _-L4 and compensates for IC breakdown voltage when integrated into an IC. At the same time, the Zener element 41
The decrease in the current flowing through the BTL drive circuit 33,
The current shunted to the Zener element 41 compensates for the operating current required for the digital circuit.

With this configuration, the volume can be easily adjusted without hindering the integration of the tone ringer circuit into an IC and without impairing the operation of the digital circuit.

<Third Embodiment> FIG. 4 shows an embodiment in which an attenuated sound removal function, that is, a function to stop the ringing immediately after the calling signal from the station stops, is added to the embodiment shown in FIG. The basic parts of the circuit are the same as those in FIG. 1B, and the same parts are given the same symbols and their explanation will be omitted. In this embodiment, a calling signal detection circuit 42 from the station is connected in series with the digital circuit 16 and the BTL drive circuit 33, and the calling signal from the station, which has been double-wave rectified by the diodes _D1 to _D4 , is sent to the detection circuit 42. After passing through, it is smoothed by a capacitor 12. Digital circuit 16 includes time monitoring counter 4
3 is added, and this counter 43 is reset by the output of the detection circuit 42 while receiving the calling signal, and starts counting after the calling signal stops.

In the circuit shown in FIG. 1B, the voltage waveform applied between the power supply terminals _L3 and _L4 due to the calling signal from the station falls as shown by the curve 44 in FIG. 5, and the ringing stop voltage If V _OFF is set low to the minimum operating voltage, even if the calling signal from the station stops, the voltage between the power supply terminals L ₃ - L ₄ will continue to decay exponentially for several 100 ms, causing the so-called decay sound. may occur.

Removal of such attenuated sound is performed in the following manner according to the embodiment shown in FIG. For example, a 16 Hz calling signal from a station is double-wave rectified by the diodes _D1 to _D4 , resulting in a double-wave rectified voltage having a pulsating current component of 32 Hz as shown in FIG. Every time this rectified voltage exceeds the charging voltage of the capacitor 12, a current flows through the calling signal detection circuit 42. The cycle of current flowing through the calling signal detection circuit 42 is 1/32≒
If the current is 31 ms and no current flows through the calling signal detection circuit 42 for 31 ms or more, it may be determined that the calling signal from the station has stopped. While current is flowing through the calling signal detection circuit 42, the time monitoring counter 43 is reset. The time monitoring counter 43 starts counting the clock signals. The monitoring time of the time monitoring counter 43 is selected to be approximately 31 ms. The output of the time monitoring counter 43 is given as an input to AND gates 18, 31, and 32 in the control circuit 17. Therefore, 31 ms after the calling signal from the station stops, the time monitoring counter 43 closes the AND gates 18, 31, and 32, and stops sending the output signal of the variable frequency divider circuit 28 to the BTL drive circuit 33. , the sounding of the sounder 36 is also stopped. Generally, the monitoring time of the time monitoring counter 43 may be set to approximately half the frequency of the calling signal from the station.

With this structure, the ringing stops several tens of milliseconds after the calling signal from the station stops, making it possible to eliminate unpleasant decaying sounds.

<Effects> As described above, according to the present invention, the digital circuit 16 that generates the ringer sound signal by digital processing and the drive circuit 33 of the sounder 36 are connected in series between the power supply terminals L ₃ and L ₄ through the terminal L _{5 .} By connecting the telephones in series through the terminals, even if two or three telephones are connected in a branch and the supply current from the office is small, the entire current supplied between the power supply terminals L ₃ - _{L 4} can be driven. Since the supplied current flows through the circuit 33 and the digital circuit 16, the supplied current can be used effectively, and by performing timbre synthesis in the digital circuit 16, it is possible to make the tonga sound multi-tone. When there is no sound, the load circuit 37 is the drive circuit 33
are connected in parallel between the power supply terminal _L4 and the series connection terminal _L5 , and all the current flowing through the non-sound load circuit 37 during non-sounding period flows to the digital circuit 16, so that the current is effectively used. In other words, the ringer circuit does not have a local power source and is configured to operate using direct current obtained by rectifying the received ringing signal. Therefore, the digital circuit 16 is the drive circuit 3.
3 and the power supply terminals L ₃ and L ₄ are connected in series via the series connection terminal L ₅ , and the non-sounding load circuit 37 is connected to the drive circuit 33 and the power supply terminal L ₄ through the series connection terminal L ₅ .
The total current flowing between the power supply terminals L ₃ and _{L 4} is connected to the digital circuit 16 in parallel when the voltage applied to the ringer circuit rises and falls, whether the ringer circuit is not ringing or ringing. It can flow and be used effectively.

In addition, it is possible to prevent false ringing, which is the minimum requirement for practical use as a tone ringer circuit for telephones, that is, to prevent resonance due to hooking of branch telephones and dial pulses, and further functions such as attenuated sound removal can be added as necessary. is easy. Therefore,
The tone ringer circuit for a telephone according to the present invention can be applied to a digital circuit using IIL (Integrated Injection), for example.
1 with bipolar linear process using
It can be implemented as a chip IC, and the tone ringer circuit can be constructed at low cost with a small number of parts. This IC conversion is carried out within the two-dot chain line in Figure 1B, and the 〇 mark on the two-dot chain line becomes the external terminal.
Among these external terminals, terminals L ₃ and L ₄ are used as power supply terminals, and L ₅ is used as a series connection terminal, and the variable resistor 14, capacitor 25, crystal oscillator 26, and sounder 36 are externally connected to these external terminals. be done. Additionally, an external terminal for tone color switching is added as necessary. Also, although not shown in the diagram, variable frequency divider circuit 2
One or more external terminals are provided for changing the frequency division ratio of 8.

[Brief explanation of the drawing]

1A shows a block diagram of a parallel-connected ringer circuit, FIG. 1A b shows a block diagram of a series-connected ringer circuit, and FIG. 1B shows an embodiment of a telephone tone ringer circuit according to the present invention. A connection diagram, FIG. 2 is a diagram showing an example of the rising waveform of the voltage applied to the circuit shown in FIG. 1B, and FIGS. 3 and 4 respectively show other embodiments of the tone ringer circuit for telephone according to the present invention. The connection diagram, FIG. 5, is a diagram showing an example of a falling waveform of the voltage applied to the circuit shown in FIG. 1B. L ₁ , L ₂ : Call signal input terminal, L ₃ , L ₄ :
Power supply terminal after rectification and smoothing of the call signal, _L5 :
Series connection terminal where BTL drive circuit 33 and digital circuit 16 are connected in series, D ₁ to D ₄ : Diode, 15 : Threshold circuit, 16 : Digital circuit, 19, 21 : Transistor switch, 20 :
Erroneous ringing prevention circuit, 37: Load circuit when no ringing, 2
4: Constant voltage circuit, 26: Crystal resonator, 27: Main oscillation circuit, 28: Variable frequency divider circuit, 33: BTL drive circuit, 34, 35: Amplifier, 36: Sounder, 42: Calling signal detection circuit, 43: Time monitoring counter.

Claims (1)

[Claims] 1. A drive circuit that drives the sounder using the power supply current from the station, a variable frequency divider circuit that divides the frequency of the reference clock to generate ringer sound signals of various frequencies, and a variable frequency divider circuit that sends the ringer sound signal to the drive circuit. A digital circuit consisting of a control circuit is connected in series via a series connection terminal, and a threshold circuit and a first A resistor element that is connected in series with the transistor switch to form an erroneous ringing prevention circuit and serves as a DC load of the circuit when no ringing is performed, and a second transistor switch;
A Zener element having a Zener voltage higher than the amplitude voltage of the pulsating flow of the supply voltage is connected in series to constitute a no-sound load circuit, and the supply voltage exceeds the voltage level set by the threshold circuit. When the first transistor switch is turned on,
the second transistor switch is rendered non-conductive;
The control circuit sends the ringing sound signal to the drive circuit, and the drive circuit is connected between the one power supply terminal and the series connection terminal, and the digital circuit is connected between the series connection terminal and the other power supply terminal. The non-sounding load circuit is connected in parallel with the drive circuit between the one power supply terminal and the series connection terminal, and the constant voltage circuit that stabilizes the power supply to the digital circuit is connected to the other power supply terminal. A tone ringer circuit for a telephone, which is connected in parallel with the digital circuit between the series connection terminals.