JPS6028197B2 - Calling signal reception method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a calling signal receiving system used in a central office line circuit of a button telephone device.

An example of the configuration of a conventional calling signal receiving system is shown in FIG. 1st
In the figure, 210 is a central telephone line, and 211 is a response circuit 2.
At the contact point of H relay 219 in 18, relay 21 is activated when responding.
9 operates to disconnect the central office line 210 and the receiving circuit, thereby preventing call loss during a call and malfunction of the receiving circuit due to noise. 212, 213
is a DC blocking capacitor.

This is a rectifier circuit for rectifying the calling signal that arrives from the 22nd line communication line 210.

Reference numeral 215 denotes a relay that operates in synchronization with the calling signal rectified by the rectifier circuit 22, and detects an incoming signal by switching the contact 270 of this relay.

217 is a false call prevention circuit, and in order to prevent the relay 215 from malfunctioning due to various noises such as surge voltage with a narrow pulse width, the operation of the relay 215 is slightly delayed using a resistor capacitor, etc. This prevents the relay 215 from temporarily malfunctioning due to the discharge current.

218 is a response circuit, and a relay 219 operates during response and communication.

As described above, in the conventional system, it is necessary to lower the input impedance of the receiving circuit in order to operate the relay with the calling signal.

Therefore, during a call, the relay contact disconnects the office line from the receiving circuit, which prevents loss of call level and prevents malfunction of the receiving circuit due to various noises from dials, hook switches, and the office line. There is a need to. For this reason, a response-only relay is essential for each office line, and it is also necessary to delay recovery immediately after a call ends to prevent malfunctions due to noise from the hook switch, office line, etc. Therefore, as the number of accommodated station wires increases, the size and weight increase, resulting in higher costs.In addition, since the input impedance of the receiving circuit is low, if an additional bell etc. is installed at the same time, relays may malfunction. There were drawbacks. The present invention uses two voltage comparison circuits to compare the DC potential obtained by rectifying the received calling signal with one reference potential provided in advance to determine whether the receiving circuit is operating or not. In addition to being able to eliminate the conventional response relay by increasing the input impedance of the circuit, it also simplifies the design of incoming call sensitivity, timer time, and prevention of false calls, and is a small, lightweight, reliable, and inexpensive calling signal receiving system. The purpose is to provide

The present invention will be explained in detail below with reference to the drawings.

FIG. 2 shows a circuit configuration diagram when the present invention is applied to a three-wire station line circuit system, and FIG. 3 shows a specific embodiment of the present invention.

In FIG. 2, one river is a central office communication line, and a case of one central office line is shown.

Reference numeral 11 denotes a control line, which transmits potential changes to the main unit to become high level, intermediate level, and low level in response to call status, hold status, and call end status, respectively, by operations on the key telephone side. It is used to transmit the station line lamp blinking signal from the main unit to each button telephone.

24 is a conventional hold music sending circuit for sending hold music such as a music box to the other party on the station line, which receives and detects a ringing signal from the station line, and receives the first incoming call in synchronization with this. This is an incoming call detection circuit for converting the signal 1 to 3 (for example, low level for 1 second, low level for 2 seconds).

50 receives the first incoming signal 13 transmitted from the incoming call detection circuit 40, and converts it into a second incoming signal by inverting and holding the output 14 from the /-i level to the low level while the calling signal is arriving. This is a timer circuit.

301 is a constant voltage circuit for setting a reference potential necessary for determining the incoming call detection sensitivity of the incoming call detection circuit 40 and the timer time of the timer circuit 50.

Reference numeral 60 is for detecting each state by comparing potential changes corresponding to each state of call, hold, and end of call transmitted from the key telephone via the control line 11 with a plurality of preset reference potentials. This is a voltage comparison circuit.

70 is a gate circuit, which is normally open and outputs signal 1.
6 is transmitted to 80' which will be described later, but it is closed only when the lamp is lit to cut off the connection between 16 and 80.

Reference numeral 80 denotes a relay driving path for receiving two parallel signals from the voltage comparison circuit 60 and operating the relay only in the case of a logic combination corresponding to a pending state.

35 is controlled by the relay drive circuit 80 to interrupt the input signals to the incoming call detection circuit 40 and the timer circuit 50 for a certain period of time (for example, 0.5 seconds) during and immediately after the end of the call. This is a delay circuit for preventing the incoming call detection circuit 40 and the timer circuit 50 from malfunctioning due to noise arriving from the incoming call detection circuit 40 and the timer circuit 50.

27 is an incoming call (e.g. 2 on the 4th) and a call on hold (e.g. I
This is a conventional intermittent circuit for generating a blinking signal for a lamp in HZ), and is composed of, for example, two oscillators and two buffer circuits, and constantly outputs the above-mentioned intermittent signal to output lines 21 and 20.

Reference numeral 90 denotes a lamp drive circuit for receiving an intermittent signal transmitted from the intermittent circuit 27 via the output lines 20 and 21, and transmitting a lamp blinking signal during incoming and on-hold calls to each button telephone via the control line 11. .

Next, an embodiment of the present invention in the main device will be described in more detail with reference to FIG.

The incoming call detection circuit 40 is composed of a transformer 42, a rectifier 43, a voltage comparator integrated circuit 46, and a smoothing circuit consisting of a resistor 44, a capacitor 45, a resistor 47, a constant voltage diode 48, etc., and has a high input impedance.

A calling signal arriving from the central telephone line 10 is sent to the relay contact 25.
, 26, after being rectified by a rectifier 43 via a capacitor 41 and a transformer 42, smoothed by a smoothing circuit including a resistor 44, a capacitor 45, and a resistor 47, and further voltage limited by a constant voltage diode 48, synchronized with the calling signal. The voltage is converted into a direct current signal and applied to the input of the voltage comparator 46. On the other hand, a resistor 31 is connected to the e input 12 of the voltage comparator 46.
A constant voltage circuit 30 composed of a constant voltage diode 32 and a constant voltage diode 32
A reference voltage corresponding to the optimum incoming call sensitivity is applied from the voltage comparator 46 when the input potential rises above this.
Since the output 13 of is inverted from low level to high level, a first incoming signal synchronized with the ringing signal is obtained and is used as a control signal for the tone ring charge. The timer circuit 50 is composed of diodes 51 and 53 having gate functions, a time constant circuit consisting of a capacitor 54 and a resistor 55, and a voltage comparator integrated circuit 56.

The input input 512 of the voltage comparator 56 is always at a low level, and when the output 13 of the voltage comparator 46 is reversed from low level to high level, the input 52 applied via the diode 51 having a unidirectional gate action is also applied with a slight delay. /. Since the voltage becomes low level, the output 14 of the voltage comparator 56 is inverted from high level to low level. Next, when the output 13 of the voltage comparator 46 recovers from the low level to the low level, the input 52 becomes the output 1 due to the gate action of the diode 51.
3, the potential of the input 52 slowly decreases with the time constant of the capacitor 54 and the resistor 55, and the output 14 maintains a low level until it reaches the reference potential of the output 12 of the constant voltage circuit 30. Therefore, the time required for the input 52 to fall from the high level to the reference potential of the output 12 of the constant voltage circuit 30 (for example, 6 seconds) corresponds to the timer time of the timer circuit 50, and the calling signal is arriving from the output 14. A second incoming call signal that is always at a low level is obtained and is used as a control signal for blinking the lamp during incoming calls. The voltage comparison circuit 60 includes resistors 61 to 64 and a voltage comparator integrated circuit 67.
, 68, and voltage changes of high level, intermediate level, and low level corresponding to call, hold, and end of a call transmitted from the key telephone via the control line 11 are applied to inputs of voltage comparators 67 and 68. .

On the other hand, reference potentials corresponding to the end of call detection level and the hold detection level are constantly applied to the e inputs of the voltage comparators 67 and 68, respectively. Note that each input of the voltage comparators 67 and 68 and the control line 11 have high impedance.
Each output 16 of the voltage comparator 67, 68 in various states,
The potential of No. 17 is as shown in Table 1. The relay drive circuit 80 in Table 1 includes resistors 81, 88 and a diode 84.
, 87, 89, transistors 82, 86, relay 85, etc.

The operation of the relay 85 causes the contacts 25 and 26 connected to the central telephone line and the contact 92 in the lamp drive circuit 90, which will be described later, to operate in addition to the saddle point 83. As shown in Table 1, only in the hold state, the output 16 is at the low level and the output 17 is at the low level, so the transistors 82 and 86 are both turned on, and at the same time as the relay 85 operates, the relay 85 is switched on by switching its own contact 83. transistor 82 is OFF
The operating state is maintained even if Next, when a response is made again from the pending state, as shown in Table 1, the output 17 becomes the level /., so the transistor 86 is turned off, the relay 85 is restored, and the pending state is released. The delay circuit 35 is a resistor 36
, a capacitor 37, and a diode 38.

According to Table 1, during a call, the output 16 is at a high level, so the transistor 82 is in the ON state, and the input of the voltage comparator 46 and the e input 52 of the voltage comparator 56 are both held at a low level, so the resistor 44 , diodes 51 and 58 are cut off. Therefore, when a call is answered when an incoming call is received, the voltage comparators 46 and 56 are restored instantly.
You can immediately stop the tone ringer sound and flashing lamp display during an incoming call. When the call ends, the potential of the input 15 is slowly increased by the time constant of the resistor 36 and the capacitor 37.
The voltage comparator 46,
56 from malfunctioning. Lamp drive circuit 9
0 is composed of resistors 91, 93, 94, 95, a capacitor 96, a diode 98, a transistor 97, etc.

As explained above, the voltage comparator 5
When the output 14 of the 6 is reversed from high level to o low level, the transistor 97 tries to turn on, but since the output 21 of the intermittent circuit 27 is constantly generating an intermittent signal corresponding to the lamp blinking cycle during the incoming call, Incoming call and output 2
1 is at a low level, the transistor 97 is turned on, and a lamp lighting signal is transmitted to each button telephone via the transistor 97, the diode 98, and the control line 11. On the other hand, even when a call is received, when the output 21 of the intermittent circuit 27 is at a high level, the transistor 97 is turned off and the lamp is turned off. Next, when the call is on hold, the transistor 97 tries to turn on by switching the contacts 83 and 92, as in the case of an incoming call, but the output 2 of the intermittent circuit 27 is always an intermittent signal corresponding to the lamp blinking cycle of the on hold. Therefore, the transistor 97 is turned ON only when the call is on hold and the output 20 is at a low level, and a lamp lighting signal is transmitted to each button telephone set via the above route. However, in this case, since the control line 11 becomes high level, the output 17 of the voltage comparator 68 also becomes low level, the transistor 86 turns OFF, and the electric appliance 85 is restored, so it is necessary to add the diode 89. Therefore, it is necessary to keep the transistor 86 in the ON state even when the lamp is lit. On the other hand, when the output 20 of the intermittent circuit 27 is at a high level even on hold, the transistor 97 is OFF.
The lamp will then turn off. As is clear from the above description, this circuit eliminates the gate circuit and reduces the number of parts by using the intermittent signals of outputs 20 and 21 as control signals for blinking lamps when a call is received and when a call is on hold. The capacitor 96 is used to appropriately delay the rise and fall times of the lamp blinking signal on the control line 11 in order to prevent click noise that occurs during the transition between the rise and fall of the lamp blinking signal. However, as the capacitance of the capacitor 96 increases, the difference in inversion time between the voltage comparators 67 and 68 increases, so the time during which the transistors 82 and 86 are simultaneously turned on transiently by the lamp blinking signal gradually becomes longer, and as a result, the relay 85 The transistor 71 and the resistor 72, 7 may malfunction.
3 is provided at the output 16 of the voltage comparator 67, and the transistor 71 is turned off only when the lamp is lit.
By turning off the voltage comparator 67 and the transistor 82 by rubbing N', the transistor 82 is forcibly turned off to prevent the above-mentioned malfunction. Next, a specific example of the button telephone will be explained in detail with reference to FIG.

120' is a secondary communication circuit, and 130 is a conventional secret communication circuit.

Reference numeral 100 denotes a power circuit consisting of a central office line button switch lol, a hold button switch 102, a constant voltage diode 103, and a hook switch 104, and the central line button switch 101 and hold button switch 102 have a conventional interlocking structure. .

During a call, a voltage of 10V appears on the control 11 via the hook switch 104, secret line circuit 130, hold button switch 102, and office line button switch 101, so that a current flows through the lamp circuit 110' of all button telephones, and the photodiode 112 is lit. When the hold button switch 102 is pressed in this state by a hold operation, the constant voltage diode 103 is inserted in series with the control line 11, so the potential of the control line 11 drops from 10V by a constant voltage due to the constant voltage diode 103. Therefore, by detecting this potential change with the voltage comparison circuit 60 in the main calendar, the pending state can be identified. Further, 110 is a lamp circuit composed of a protective resistor 111 and a light emitting diode 112, and is mounted on each button telephone in an amount corresponding to the total number of stations. As is clear from the above explanation, in the method of the present invention, the first incoming signal is intermittent in synchronization with the intermittence of the incoming call signal when the calling signal arrives, and the second incoming signal maintains a constant DC level while the calling signal continues. In order to detect this, the first incoming signal is extracted by detecting the change in the DC level obtained by rectifying the ringing signal, and the on/off signal is detected in the intermittent (on/off) change of the first incoming signal. Unidirectional gate with diode to maintain signal level even when off.
Since the second incoming signal is extracted using the time constant effect of the time constant circuit and the time constant characteristic of the time constant circuit, the load current flowing from the input side is extremely small, and the receiving circuit has a high input impedance. This makes it possible to reduce call loss even if the line is always connected to the central office telephone line, which makes it possible to reduce the total amount of electrical equipment and to digitize it. In addition to making it possible to reduce the size and weight and cost by using an IC, it is also possible to easily set the optimum incoming sensitivity and timer time depending on the setting of the reference potential, and it is also easy to design the incoming call prevention circuit. The purpose is achieved.

In addition, since the present invention can increase the input impedance,
It is possible to simultaneously ring an additional bell or a power outage bell to display an incoming call in the event of a power outage or failure, and the type of waveform (sine wave, square wave) and frequency (16Hz, 20Hz) of the ringing signal can be set. It has the advantage that it can be used for both rotary dial type and push button dial type central office lines.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a conventional calling signal receiving circuit.
FIG. 2 is a block diagram showing an embodiment of the invention, and FIG. 3 is a circuit diagram showing an embodiment of the invention. Outside figure 1 figure N dog spear figure 3

Claims (1)

[Claims] 1. A first incoming call signal that receives a calling signal from a central office line, compares the rectified output potential with a first reference potential, and extracts a first incoming signal that is synchronized with the interruption of the calling signal. a comparator; a time constant circuit that holds a DC potential during the rectification of the first incoming signal with a predetermined time constant when the signal is cut; and a time constant circuit that compares the DC potential with a second reference potential. Second continuous DC output
a second voltage comparator for extracting the incoming output of the incoming call, and is configured to be able to determine whether the incoming call signal is received. 2. The calling signal receiving system according to claim 1, wherein the first reference potential and the second reference potential are the same potential. 3. The first voltage comparator and the second voltage comparator are connected to each input side during a call and for a certain period of time immediately after the call ends.
3. The calling signal receiving system according to claim 1, further comprising a circuit for rendering the voltage comparator and the second voltage comparator inactive.