JPH1051816A - Analog subscriber circuit in exchange provided with on-hook transmission function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent mis-detection of a loop detection circuit without decreasing a feeding current in an analog subscriber circuit in an exchange provided with an on-hook transmission function sending information data to a terminal equipment for a pause period of a ringer in an on-hook state at the arrival of a call to the terminal equipment. SOLUTION: This subscriber circuit is provided with a feeding circuit 1, a loop detection circuit 2, a ringer transmission circuit and a circuit outputting information data to a subscriber line. The feeding circuit 1 is provided with a power supply generating circuit 10b supplying power to two lines constituting a subscriber line and a bias circuit 11b and supplying a bias voltage to a power supply voltage generated from the power supply generating circuit 10b. Then the loop detection circuit 2 detects presence of a loop to activate the bias circuit 11b of the feeding circuit 1, and when absence of loop is detected, the bias circuit 11b of the feeding circuit 1 is controlled to be inactive.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an analog subscriber circuit in an exchange having an on-hook transmission function.

[0002] On-hook transmission (On-Hook transmission) is a method of transmitting information data (such as a calling subscriber number) when a terminal device is on-hook (when a handset is placed) when an incoming call arrives at a subscriber terminal of a telephone exchange. -Transmission: OH
T) method.

The function of the on-hook transmission system has been mainly applied to digital subscriber circuits such as ISDN, but can be applied to analog subscriber circuits. In such a case, it is desired to transmit information data (AC signal) to the terminal in the on-hook state to accurately detect the off-hook state.

[0004]

2. Description of the Related Art FIG. 19 is an explanatory diagram of the OHT method. FIG. Indicates a connection configuration for executing the on-hook transmission function, FIG. 4 is a diagram showing a change in a signal of a subscriber circuit.

FIG. , 80 denotes a terminal such as an analog telephone, 81 denotes a hook switch which is turned off when the handset is placed and turned on when the handset is removed, and 82 is information data provided in the terminal 80 and transmitted in the form of an AC signal. Receiving terminal, 83 is a receiving circuit, 84 is a capacitor,
85 is a subscriber line, 86 is an exchange, and 87 is an analog subscriber circuit.

FIG. The operation of the on-hook transmission will be described with reference to FIG. When an incoming call to the terminal 80 occurs in the exchange 86, a ringer signal (B.) is sent from the subscriber circuit 87 to the terminal 80 via the subscriber line 85 in a form in which a cycle of a ringer sending section and a silent section is repeated at a constant cycle. Sent out. During a silent period between the first ringer delivery time and the second ringer delivery time, an OHT signal (of B.) indicating the OHT mode is supplied to the subscriber circuit 87 from a control device (not shown) of the exchange.
During the OHT mode, the down (down) highway D
The information data such as the calling subscriber number to be sent from the HW to the terminal 80 is input, and the information data (B.) of the AC signal is sent out on the subscriber line 85. At this time, the terminal 80
Is in the on-hook state (hook switch is off),
The subscriber line information data receives the AC signal information data at the receiving terminal 82 and performs operations such as displaying it on a display device (not shown).

A subscriber circuit for realizing the above OHT method will be described with reference to FIGS. FIG. 20 is a configuration diagram of the first conventional example, and FIG. 21 is a diagram illustrating an operation example of the first conventional example. 20, reference numerals 90 to 94 denote subscriber circuits (8 in FIG. 19).
90 is a ringer sending circuit;
1 is a power supply circuit, 92 is a loop detection circuit, 93 is a hybrid that performs mutual conversion between two subscriber lines and four lines on the codec side, and 94 is a mutual conversion between analog signals on the subscriber line and digital signals on the exchange side. A and B are two subscriber lines (corresponding to 85 in FIG. 19).

[0008] The operation of the subscriber circuit of the first conventional example will be described with reference to FIG.
A, B of the subscriber line as shown in the head position of 1,
VBB (−48 V is often used) and G (ground potential) are supplied from the power supply circuit 91 to the lines, respectively. At this time, the loop detection circuit 92 detects the voltage of the A line and the B line, determines whether the voltage of the B line is lower than a preset threshold voltage (B line Vth), and determines the voltage of the A line. Is higher than a preset threshold voltage (A line Vth). A
When this condition is satisfied for both the line and the B line, there is a loop as the output signal LP of the loop detection circuit 92 (the DC loop was formed by being off-hook at the subscriber terminal).
Is output.

When the OHT mode signal is generated as shown in FIG. 21 during the silent period of the ringer signal transmission at the time of an incoming call to the terminal 80, the bias circuit 910 of the power supply circuit 91
911, a loop detection circuit 92 and a codec 94 are driven. The bias circuits 910 and 911 thereby provide A,
A bias voltage is generated on the B line, and the voltage changes as shown in FIG. In this state, when the information data shown in FIG. 21 is input from the DHW, the pre-driven codec 94 decodes the information data, and the output is output to the A and B lines via the hybrid 93. An AC signal superimposed on the bias voltage as shown in FIG. At this time, in the loop detection circuit 92 to which the OHT mode signal has been supplied, the threshold voltage Vth is changed as shown in FIG.
Even if the voltage of the A line and the B line is a bias voltage or a bias voltage and an AC signal are applied, it is prevented that a loop is erroneously detected.

[0010] In the conventional example 1, when the OHT mode is restored,
It is necessary to return the voltage levels of the A and B lines to the original state by turning off the bias circuit, and also to return the threshold voltage Vth to the original state. However, since the voltages of the A and B lines have a time constant, they gradually change, and at the positions indicated by “X” in the waveforms of FIG.
The erroneous LP signal indicating that there is a loop is generated from the loop detection circuit 92 for a very short time as shown to exceed th. In order to prevent this, it is necessary to take measures such as giving a time constant to Vth and masking an erroneous LP signal.

FIG. 22 is a block diagram of the second conventional example, and FIG. 23 is a diagram showing an operation example of the second conventional example. In FIG.
Reference numeral 94 is the same as that of each of the above-described conventional examples 1 (FIG. 20), and a description thereof will be omitted. The second conventional example differs from the first conventional example in that bias circuits 910 and 911 in the power supply circuit 91 are provided.
Is a point at which a bias voltage is constantly applied to the A and B lines, thereby preventing the generation of an erroneous LP signal as in the conventional example 1.

The operation of the conventional subscriber's circuit will be described with reference to FIG. 23. When the terminal 80 is in the on-hook state, FIG.
A, B of the subscriber line as shown in the head position of 3,
G (ground), VB
Bias is applied from the potential of B by voltages VA and VB,
When the ringer is transmitted and the OHT mode signal is generated in the silent section as shown in FIG. 23 and the AC signal is generated from the codec, the threshold voltage Vth does not change. Then, a detection signal indicating the presence of a loop is generated as shown in FIG.

According to the second conventional example, there is no need to change the bias of the power supply circuit and the threshold voltage of the loop detection circuit by the OHT signal. If the codec is always powered on, the OHT signal becomes unnecessary.

[0014]

In the configuration of the second prior art (FIG. 22), a bias voltage is constantly applied.
When the subscriber of the terminal goes off-hook (when responding to the ringer at the time of incoming call and at the time of calling), the supply current is smaller than when there is no bias current. Describing in a specific example, power supply resistance (internal resistance of power supply circuit) = 250Ω × 2, VBB = −48
V, line resistance = 1900Ω, bias voltage = VB + VA
In the case of = 8V, feed current without bias = | VBB | / (feed resistance + line resistance) = 48V / (250Ω x 2 + 1900Ω) = 20mA (milliampere) Feed current with bias = (| VBB |- bias)
/ (Feeding resistance + line resistance) = (48V-8V) / (250Ω × 2 + 1900
Ω) = 16.7 mA (milliamps) When the bias is constantly applied, if the supply current decreases, the line length between the switch and the subscriber's terminal must be shortened to operate the switch circuit normally. There was a problem that it was necessary to reduce the resistance.

An object of the present invention is to provide a subscriber circuit in an exchange having an on-hook transmission function capable of preventing erroneous detection of a loop detection circuit without reducing a supply current.

[0016]

FIG. 1 is a block diagram showing the principle of the present invention. In FIG. 1, reference numeral 1 denotes a power supply circuit, 10a, 10
b is a power supply generating circuit for generating power to the A and B lines connected to the subscriber's terminal, 11a and 11b are bias circuits, 2 is a loop detection circuit, 3 is a hybrid circuit, and 4 is a codec.

In the present invention, L generated from the loop detection circuit 2
When the P signal is input to the bias circuits 11a and 11b of the power supply circuit 1 and the terminal (not shown) is in the on-hook state and the loop detection circuit 2 detects the on-hook, the bias on signal is supplied to the bias circuits 11a and 11b of the power supply circuit 1. Is sent. The bias circuits 11a and 11b generate a bias voltage in response thereto, and the power supply generation circuits 10a and 10b generate a power supply voltage to which the bias voltage is added and supply the generated power supply voltage to the A line and the B line. During this on-hook state, the OH
In the T mode, information data can be transmitted to a codec (not shown).

When the terminal goes off-hook, the loop detection circuit 2 detects the off-hook and sends a bias-off signal to the bias circuits 11a and 11b of the power supply circuit 1. The bias circuits 11a and 11b stop generating the bias voltage in response thereto, and the power generation circuits 10a and 10b generate the power supply voltage excluding the bias voltage and supply the generated power supply voltage to the A and B lines. Thus, the bias voltage is lost in the off-hook state, so that the power supply current does not decrease.

[0019]

FIG. 2 is a block diagram of the first embodiment, and FIG. 3 is an example of operation waveforms of various parts of the first embodiment. In FIG.
Reference numerals 1, 10a, 10b, 11a, 11b, and 2 to 4 correspond to the respective circuits having the same reference numerals in FIG. 1 and have the same names. 5 denotes a terminal, OHT denotes an on-hook transmission signal (referred to as an OHT signal),
UHW indicates an upper highway for transmitting an upward signal, DHW indicates a down highway for transmitting a downward signal, and LP indicates an output signal (referred to as an LP signal) of the loop detection circuit 2.

The operation of the first embodiment shown in FIG. 2 will be described with reference to FIG. In the on-hook (ON-HOOK) state shown in FIG. 3, the voltages of the lines B and A are applied with the bias voltages VB and VA to the voltages G and VBB of the power supply, respectively, as shown by. As shown from a comparison circuit (indicated by CMP) 2b which compares the voltage Vab obtained by adding the voltages of the A line and the B line by the voltage addition circuit (or the current sum circuit) 2a with a threshold voltage Vth, LP = no loop shown “H” is output.

When the terminal 5 enters an off-hook state as indicated by an operation such as raising the handset, an LP indicating a loop is present as indicated by the comparison circuit 2b of the loop detection circuit 2.
= “L” is output. This output signal is sent to a control circuit (not shown) and bias circuits 11a, 11b
, The bias circuits 11a and 11b stop generating the bias voltage, and the B and A lines change to the loop voltages Vb and Va shown in the off-hook state of FIG. At this time, the threshold voltage Vth supplied to the comparison circuit 2b is also in the off-hook state.
(Controlled by the output signal of the loop detection circuit 2). In this manner, in the on-hook state, the bias supply to the A-line and the B-line is performed, and the information data is properly transmitted in the OHT mode. In the on-hook state, the supply of the bias voltage is stopped to reduce the power supply current. Nothing.

Next, a problem in the configuration of the first embodiment will be described with reference to FIGS. FIG. 4 is a diagram showing a problem when receiving a dial pulse. When a dial-type telephone is used as the terminal 5 in FIG. 2, when the dial is turned off-hook, the internal resistance of the telephone changes from several tens to several hundreds Ω to 0 Ω in response to the break and make. In the example of FIG. 4, the dial number is "3", and the voltage Vab between the A and B lines changes according to the dial pulse, and an output corresponding to the dial is generated by the output voltage of the loop detection circuit shown in FIG. I do. After the dial pulse is transmitted, when the internal resistance of the telephone returns from 0Ω to several tens to several hundreds Ω, the voltage Va between the A and B lines
b drops momentarily as shown in FIG.

This is caused by the operation of a C-position circuit (a well-known relay circuit that is turned on only during the section of each dial pulse and turned off when the operation is completed) provided in the dial pulse transmission circuit of the conventional telephone. Thus, A,
Since Vab of the line-to-line voltage Vab decreases, LP = “H” indicating no loop (on-hook) is generated from the loop detection circuit 2 for a short time, and the bias voltages are generated from the bias circuits 11a and 11b and the threshold voltage Vth is also reduced. Change. Such an erroneous LP signal indicating that there is no erroneous loop is several μs to several ms in a circuit that does not change Vth.
These pulses can be sufficiently removed by the pseudo-pulse absorption circuit of the loop detection circuit. However, in the first embodiment in which Vth changes, the erroneous LP signal time is several tens of ms, and cannot be removed by the pseudo-pulse absorption circuit.

FIG. 5 is a diagram showing a problem when the line voltage becomes close to the threshold. In the configuration of FIG. 2 of the first embodiment, when the voltage Vab between the A and B lines becomes greater than the threshold voltage Vth when the hook is off-hook, the loop detection circuit 2 detects the presence of a loop and the threshold voltage th shown in FIG. Vab indicated by 5 gradually decreases due to the time constant of the power supply circuit 1. However, when Vab <Vth due to undershoot, Vth increases and Vab rises.
Gradually falls. By repeating this, oscillation occurs, and an output corresponding to the oscillation shown in FIG. 5 is generated from the loop detection circuit 2.

A second embodiment for preventing the problems shown in FIGS. 4 and 5 is shown in FIG. FIG. 6 is a configuration diagram of the second embodiment, and FIG. 7 is an example of an operation waveform of each unit of the second embodiment. In FIG. 6, 1, 2, and 5 correspond to the respective symbols of the first embodiment, 1 is a power supply circuit, 2 is a loop detection circuit, 5 is a terminal, and the hybrid circuit 3 and the codec 4 are not shown. .
Further, 2a in the loop detection circuit 2 is a circuit for adding the voltages of the A line and the B line, 2c is a pulse absorption circuit, 2d is a comparison circuit (CMP1) for comparing the threshold voltage Vth with the output of the pulse absorption circuit 2c, 2e. Is the threshold voltage Vt
A comparison circuit (CMP2) for comparing h with Vab.

In the second embodiment, one of the outputs of the A and B line voltage adding circuits 2a is supplied to a pulse absorbing circuit 2c which suppresses a rapid change of an input signal, and the other is supplied to a comparing circuit 2e. The output Vps that has passed through the pulse absorbing circuit 2c is compared with a threshold voltage Vth by a comparing circuit 2d, the output BC is supplied to bias circuits 11a and 11b, and the output of the comparing circuit 2e is output as an LP signal.

Referring to FIG. 7, this example shows a case where a dial pulse (numeral "3") is generated after an on-hook state is established as in the case of FIG. 4 described above.
Even if the voltage Vab between the lines changes as shown by the solid line, the signal Vps shown by the dotted line is generated from the pulse absorbing circuit 2c and changes slowly. The signal Vps maintains the loop mode during the period in which the dial pulse is generated, so that the output BC generated from the comparison circuit 2d eliminates the malfunction of the C position circuit and the bias circuit due to noise as shown in FIG. The generation of the LP signal can be prevented. Further, since the bias circuits 11a and 11b are controlled by the output BC, it is possible to eliminate a malfunction of the bias circuit. In addition, since the filter of the pulse absorption circuit 2c is added to the undershoot of Vab at the time of detecting the loop, Va
b <Vth is not satisfied, and oscillation can be prevented.

FIG. 8 shows a configuration example 1 of the pulse absorbing circuit.
This pulse absorbing circuit forms a filter (low-pass filter) with a resistor R and a capacitor, and removes a steep pulse-like signal component by using it as the pulse absorbing circuit 2c in FIG.

FIG. 10 is a configuration diagram of the third embodiment, FIG. 9 shows a second configuration example of the pulse absorbing circuit, and FIG. 11 shows an example of an operation waveform of each part of the third embodiment. In FIG. 10, 1, 2, and 5 correspond to the respective symbols in the first embodiment (FIG. 2) and the second embodiment (FIG. 6), 1 is a power supply circuit, 2 is a loop detection circuit, 5 is a terminal, The hybrid circuit 3 and the codec 4 are not shown. 2a in the loop detection circuit 2 is line A, B
Line voltage adding circuit, 2b is a threshold voltage Vth
And a comparison circuit (CMP) for comparing the output of the addition circuit 2a
2f is a pulse absorption circuit.

In the third embodiment shown in FIG. 10, unlike the second embodiment, the output of the comparison circuit 2b of the loop detection circuit 2 is output as a loop signal LP to the control device of the exchange and supplied to the pulse absorption circuit 2f. As a result, in the pulse absorbing circuit 2c of the second embodiment, the input voltage Vab is
When -48V is used, a circuit which can reach about -46V and can cope with the voltage must be constructed. On the other hand, the pulse absorbing circuit 2f of the third embodiment is limited to about 5V and is a general-purpose circuit. Can be configured.

FIG. 9 shows a configuration example 2 of the pulse absorption circuit.
It has the same resistor R and capacitor C as in the configuration example 1 of the pulse absorption circuit shown in FIG. 8, and further has a comparison circuit (CMP) 30 to which an output signal (indicated by Vip) is input. The comparison circuit 30 compares the signal Vip with the threshold voltage Vthp to generate a signal BC for controlling the bias circuits 11a and 11b.

FIG. 11 shows an example of the operation waveform of the third embodiment of FIG. 10 using the pulse absorbing circuit shown in FIG. 9, and this example also becomes the on-hook state similarly to the case of FIG.
This is a case where a dial pulse (number “3”) is generated.

The voltage Vab of the A-line and B-line circuits shown in FIG. 4 is output from the adder circuit 2a and compared with the threshold voltage Vth shown in the comparison circuit 2b, and an LP signal shown as an output is generated. When this LP signal is input to the pulse absorption circuit 2f, the output signal VLp of the R and C circuits of the pulse absorption circuit shown in FIG. 10 is supplied to the comparison circuit 30 (FIG. 9) with the waveform shown in FIG. By comparing with the threshold voltage Vthp shown in FIG.
A signal is generated, and the bias circuit 11a, 1
1b is controlled to change the bias voltage as shown in FIG. Also in this case, a short pulse such as a dial pulse signal is removed at the time of off-hook, and the bias circuit can be held in the loop mode.

FIG. 12 shows a third example of the configuration of the pulse absorbing circuit, and FIG. 13 shows an example of the operation waveform of each part of the third embodiment when the pulse absorbing circuit of FIG. 12 is used. In FIG.
Reference numeral 31 denotes a counter (indicated by CN1), and reference numerals 32 and 33 denote flip-flop circuits (hereinafter referred to as FF1 and FF2).

An example of the operation of the third embodiment when the pulse absorbing circuit of FIG. 12 is used will be described with reference to FIG. First, the clear signal (CLR) = "L" is output from the counter 31, F
The output of the carry-out (CO) of the counter 31 is "L", the output Q of the FF2 is "L", and the output Q of the FF1 is "H".

When the LP signal is "H" at the time of on-hook, BC
The signal (output of FF1) is “H” and the power supply circuit (FIG. 1)
0) 1) becomes the OHT mode. L off-hook
When the P signal becomes "L", this signal is input to the clear (CL) terminal of the FF1, so that the signal BC generated from the output terminal Q of the FF1 becomes "L", and the power supply circuit enters the loop mode. Further, the counter 3 is set by the LP signal = "L"
1 is driven, and the input of the mask time setting applied to the input terminals A to D is loaded.

In this description, assuming that the terminals A to D are "0", the outputs of the output terminals QA to QD and CO (carry out) of the counter 31 are "L" and the FF2
Since the output Q = “L”, the clock terminal CK of the FF1
Is not driven, and FF1 does not operate.

During the loop mode (BC signal = “L”), the break pulse of the dial pulse (L in FIG. 13)
When the "H" section represented by DP1 and DP2 in the P signal occurs, the LP signal becomes "H", the load of the counter 31 is released, and the clock (CLK) signal is input from the terminal CK to count. Start. However, since the section indicated by DP1 and DP2 of the LP signal in FIG.
1 is a state in which the output terminals QA and QB have become "H" (count value "3"), the dial pulse becomes a make state (off-hook state), the LP signal becomes "L", and the counter 31 is loaded again. State, the terminal CO is kept at "L", and the mask is
The signal is prevented from becoming "H" (OHT mode).

When the on-hook state is returned to the on-hook state after DP2 and the LP signal returns to "H", the counter 31 starts counting and counts the number of clock signals set as the mask time setting. When the number of clock signals is counted, output terminals QA to QD = "H"
And the terminal CO becomes "H". The "H" of this terminal CO is supplied to the data input D of the FF2 and is set in synchronization with the clock, so that the output Q becomes "H".
It is supplied to the clock input CK of F1 to set "1" of the data input D, and "H" is generated from the output Q, output as a BC signal, and return to the OHT mode.

In this way, B from which short pulses have been removed
The C signal is applied to the bias circuits 11a and 11b of the power supply circuit 1, and the bias circuit is held in the loop mode. In addition,
In this example, since the input terminals A to D are all "0" in the mask time setting, 15 clock cycles are the max time until the carry-out CO occurs.

FIG. 14 shows a configuration example 4 of the pulse absorbing circuit. In the figure, reference numerals 31 to 33 denote the same circuits as those having the same reference numerals in FIG. 12, and reference numeral denotes a ringer mask circuit. In the configuration example 4, the ringer mask circuit 34 is provided on the path through which the LP signal passes in the configuration shown in FIG. In this configuration example, when the ringer signal is repeatedly turned on and off, the loop detection circuit erroneously has a loop (LP signal =
"L") is detected in some cases, and such an erroneous loop is prevented from being detected.

FIG. 15 shows a configuration example 1 of the ringer mask circuit. In FIG.
FF6 is provided with a preset terminal (PR). When a signal that changes from "H" to "L" is input to this terminal, presetting is performed and the output Q is set to "H" while the "L" input is maintained. , And flip-flop circuits AND1,
AND2 is an AND circuit, and OR1 is an OR circuit 1.

This ringer mask circuit is provided for masking the LP signal for a certain period of time from the operation and recovery of the relay for switching the ringer signal and maintaining the OHT mode.

FIG. 16 shows an example of operation waveforms of the pulse absorbing circuit including the ringer mask circuit shown in FIG. 15, which will be described below. The FF3 and FF4 of the ringer mask circuit of FIG. 15 are cleared by the clear signal (CLR) in the initial setting, and the respective outputs Q = "L", so that no masking is performed. When a ringer (indicated by RNG) signal changes from off to on, a signal from “H” to “L” generated by being inverted by the inverter (INV1) is output to the preset terminals (P) of FF3 and FF4.
R), the output Q of FF3 and FF4 becomes "H", but the other input of the AND circuit 1 (AND1) becomes "L" when the ringer is on, so that the output becomes "L" and there is no mask. Becomes

Thereafter, the FF3 and FF4 are connected to the ringer (R
When NG) changes from ON to OFF, the preset is released and the rising edge of the clock signal (CKR) is supplied to the terminal CK.
(Fixed to “0”) is set, and “L” is output from the output Q. Then, when the next clock signal rises, FF4
Is also set to "0" because "L" of the output Q of the FF3 is input to the data input terminal D, and the output Q
Generates "L" from Thus, even if the LP signal erroneously generates an erroneous pulse indicating that there is a loop within a predetermined time immediately after the ringer (RNG) is switched from on to off, the output of the inverter 1 and the FF4 is output by the AND circuit 1 (AND1). "H" is output by AND of the OR circuit 1 (O
During the period in which the erroneous pulse is generated from R1), the LP 'signal masking the erroneous pulse is output, and the OHT mode can be maintained.

On the other hand, as shown in FIG. 16, when the ringer (RNG) signal changes from on to off, the preset terminals (PR) of the FF5 and FF6 are driven, and the respective outputs Q output "H". , And the other input of the AND circuit 2 (AND2) is "L" when the ringer is off, so that its output becomes "L" and there is no mask. When the ringer signal is switched from off to on, the preset is released and FF3 is set to "0" at the rising of the next clock (CKR), and FF3 is set at the rising of the next clock (CKR).
4 is set to "0", and "L" is generated sequentially from each output Q. At this time, LP from AND circuit 2 (AND2)
“H” for masking the erroneous pulse of the signal is output, and the OR ′ circuit 1 generates an LP ′ signal that does not include the erroneous pulse.

FIG. 17 shows a configuration example 2 of the ringer mask circuit. This ringer mask circuit is used as the ringer mask circuit 34 in the pulse absorption circuit shown in FIG. In FIG. 17, INV2 is an inverter 2, FF7 to FF.
Reference numeral 12 denotes a flip-flop circuit having a preset terminal, and OR2 denotes an OR circuit 2.

FIG. 18 shows an example of operation waveforms of the pulse absorbing circuit (FIG. 14) including the ringer mask circuit shown in FIG.
In this example, the ringer sending period (for example, if the ringer-on is 1
This is an example of an operation in which the LP signal is masked during the period of 2 seconds and the ringer-off period is 3 seconds, and the OHT mode is maintained while the ringer is being transmitted.

When a clear signal (CLR) is first generated while the ringer (RNG) signal is off, all the flip-flop circuits FF7 to FF12 in FIG. 17 are cleared, and the respective outputs Q become "L". , No mask. Ringer transmission starts and the ringer (RNG) signal is
As shown in FIG.
Since the signal inverted at (INV2) is input to each of the preset terminals of FF7 to FF12, they are respectively preset and all the outputs Q become "H" as shown in FIG. 18 to start masking. The mask is executed by ORing the signal of the output Q of the FF 12 and the LP signal by the OR circuit 2 (OR2), and the output signal LP 'becomes a loop signal.

When the ringer is turned off, the data input (D) = "0" of the FF 7 is set at the rising edge of the clock (CKS), and the output Q becomes "L". As shown in FIG. 18, at the rising of the next clock (CKS), FF8
Is set to "L" from the output Q of the FF 7, the output Q also becomes "L", and the output Q of the FF 9 also becomes "L" by the next clock (CKS). However, the linger is turned on before “L” reaches FF12, and FF7 to FF7 are turned on.
12 is preset again, all the outputs Q become "H", and when the ringer is turned off, the above operation is executed.

When the ringer transmission is completed, FF7 to FF1
2 shifts “L” at every rising edge of the clock (CKS), and finally the output Q of the FF 12 becomes “L”, and the masking ends. In this way, the operation of the ringer relay,
The erroneous LP signal at the time of restoration can be masked, and the OHT mode can be maintained.

[0052]

According to the present invention, when the method of switching the bias voltage of the power supply circuit during the on-hook transmission is used, it is possible to eliminate the transmission of an erroneous loop signal, and to reduce the power supply current by constantly generating the bias voltage. Can be reduced. In addition, the pulse absorption circuit can prevent oscillation that repeatedly turns on and off when the bias voltage changes. Further, by providing a ringer mask in the pulse absorbing circuit, it is possible to prevent a malfunction of the bias circuit when the ringer is transmitted.

[Brief description of the drawings]

FIG. 1 is a principle configuration diagram of the present invention.

FIG. 2 is a configuration diagram of a first embodiment.

FIG. 3 is a diagram illustrating an example of an operation waveform of each unit according to the first exemplary embodiment.

FIG. 4 is a diagram showing a problem when receiving a dial pulse.

FIG. 5 is a diagram illustrating a problem when a line voltage becomes close to a threshold.

FIG. 6 is a configuration diagram of a second embodiment.

FIG. 7 is a diagram illustrating an example of an operation waveform of each unit according to the second embodiment.

FIG. 8 is a diagram illustrating a configuration example 1 of a pulse absorption circuit.

FIG. 9 is a diagram illustrating a configuration example 2 of the pulse absorption circuit.

FIG. 10 is a configuration diagram of a third embodiment.

FIG. 11 is a diagram illustrating an example of an operation waveform of each unit according to the third embodiment.

FIG. 12 is a diagram illustrating a configuration example 3 of the pulse absorption circuit.

FIG. 13 is a diagram illustrating an example of operation waveforms of each unit of the third embodiment when the pulse absorption circuit of FIG. 12 is used.

FIG. 14 is a diagram illustrating a configuration example 4 of the pulse absorption circuit.

FIG. 15 is a diagram illustrating a configuration example 1 of a ringer mask circuit.

16 is a diagram showing an example of an operation waveform of a pulse absorption circuit including the ringer mask circuit shown in FIG.

FIG. 17 is a diagram illustrating a configuration example 2 of a ringer mask circuit.

18 is a diagram showing an example of an operation waveform of a pulse absorption circuit including the ringer mask circuit shown in FIG.

FIG. 19 is an explanatory diagram of the OHT method.

FIG. 20 is a configuration diagram of Conventional Example 1.

FIG. 21 is a diagram showing an operation example of Conventional Example 1.

FIG. 22 is a configuration diagram of Conventional Example 2.

FIG. 23 is a diagram showing an operation example of Conventional Example 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power supply circuit 10a, 10b Power generation circuit 11a, 11b Bias circuit 2 Loop detection circuit 3 Hybrid circuit 4 Codec

Claims (7)

[Claims] 1. An analog subscriber circuit in an exchange having an on-hook transmission function for transmitting information data to a terminal while a ringer is inactive while in an on-hook state when an incoming call arrives at the terminal. A detection circuit, a ringer sending circuit, and a circuit for outputting information data to the subscriber line, wherein the power supply circuit generates a power from the power generating circuit for supplying power to two lines constituting the subscriber line; A bias circuit for supplying a bias voltage to the power supply voltage to be supplied. The loop detection circuit turns off the bias circuit of the power supply circuit when detecting the presence of a loop, and turns on the bias circuit of the power supply circuit when detecting no loop. Analog subscriber circuit in exchange with on-hook transmission function characterized by controlling . 2. The loop detecting circuit according to claim 1, wherein the loop detecting circuit includes an adding circuit for adding a voltage or a current of two lines forming the subscriber line, and one of outputs of the adding circuit is connected to a pulse absorbing circuit. And a second comparison circuit to which the other of the outputs of the adder circuit is inputted, wherein the first comparison circuit compares the level of the inputted current or voltage with a comparison voltage. The comparison result is supplied as a control signal of the bias circuit, and the second comparison circuit outputs a result of comparing the level of the input current or voltage with a comparison voltage as a signal indicating a loop state. Analog subscriber circuit in an exchange with on-hook transmission function. 3. The loop detection circuit according to claim 1, wherein the loop detection circuit compares an output of the addition circuit with a comparison voltage for adding a current or voltage level of two lines constituting the subscriber line. And a pulse absorbing circuit to which an output of the comparing circuit is output as a signal indicating a loop state and to which an output of the comparing circuit is supplied, wherein an output of the pulse absorbing circuit is supplied to a control signal of the bias circuit. An analog subscriber circuit in an exchange having an on-hook transmission function, characterized in that the circuit is supplied as a telephone. 4. The pulse absorption circuit according to claim 2, wherein the pulse absorption circuit has a configuration of a low-pass filter using a capacitor and a resistor, or a configuration including the low-pass filter and a comparison circuit for comparing an output of the low-pass filter with a comparison voltage. An analog subscriber circuit in an exchange having an on-hook transmission function, comprising: 5. The pulse absorption circuit according to claim 3, wherein the pulse absorption circuit controls a bias circuit controlled by a counter for measuring a mask time set when the loop signal indicates on-hook, and a bias circuit controlled by an output of the loop signal and the counter. A flip-flop circuit for generating a signal, wherein the flip-flop circuit masks the on-hook signal until the counter reaches a set time when the loop signal indicates on-hook from off-hook until the counter reaches a set time. An analog subscriber circuit in an exchange having an on-hook transmission function. 6. The pulse absorbing circuit according to claim 5, further comprising a ringer mask circuit to which the loop signal is input and to which a ringer signal is supplied, wherein the ringer mask circuit operates and recovers the ringer signal. An analog subscriber circuit in an exchange having an on-hook transmission function, wherein an output obtained by masking an erroneous loop signal is supplied to the counter and the flip-flop circuit. 7. The pulse absorbing circuit according to claim 5, further comprising: a ringer mask circuit to which the loop signal is input and a ringer signal is supplied, wherein the ringer mask circuit operates and recovers the ringer signal. An analog subscriber circuit in an exchange having an on-hook transmission function characterized in that a mask signal is continuously generated during a ringer transmission period in order to mask an erroneous loop signal.