WO1993001676A1

WO1993001676A1 - Ringing trip judging circuit

Info

Publication number: WO1993001676A1
Application number: PCT/JP1992/000863
Authority: WO
Inventors: Kazuyuki Minohara; Kenji Takato
Original assignee: Fujitsu Limited; Fujitsu Communication Systems Limited
Priority date: 1991-07-08
Filing date: 1992-07-07
Publication date: 1993-01-21
Also published as: JPH06121038A

Abstract

A ringing trip judging circuit, which, on calling, senses a change from the on-hook to off-hook state of a terminal such as a telephone set connected to a telephone circuit, is provided with a ringing trip sensing resistor which is connected in series with a ringer generator and senses the change of a current value from the on-hook to off-hook state, a sensing section for sensing the change of the voltage across the ringing trip sensing resistor, a voltage comparing section which compares the output voltage of the sensing section with a threshold voltage and outputs two different voltages depending on the result of comparison, a state retaining section (1) which retains different state values according to the different output values of the voltage comparing section and outputs them, a state retaining section which latches at least two state values outputted by the state retaining section (1) and outputs them, and a state judging section for comparing the state values of the state retaining sections with each other. The state judging section judges the voltage changes, which are sensed by the ringing trip sensing resistor at different times when the ringing trip sensing section senses the on-hook and off-hook states by comparing the state values of the state retaining sections, and senses the on-hook and off-hook states of the terminal equipment.

Description

Details

[Title of Invention]

Ring trip judgment circuit

〔Technical field〕

The present invention relates to a ring trip for detecting a change from an on-hook state to an off-hook state of a terminal when a terminal device such as a telephone connected to a telephone line is called. Regarding the judgment circuit.

(Background technology)

The detection of the change from the on-hook state to the off-hook state when a terminal device connected to the telephone line is ringing is detected by a ring trig in series with the ringer generator. Connect a circuit detection resistor, and the off-hook due to the on-hook and the terminal device response generates a change in the current flowing through the ring-trip detection resistor. O By detecting the voltage change

The value of the current flowing through the ring trip resistor and the rate of change in the on-hook and off-hook conditions during off-hook and off-hook are determined by the line length of the telephone line and the connection. Depending on the load conditions such as the number of terminal devices, accurate detection of on-hook and off-hook was difficult.

Fig. 1 is an explanatory diagram of the ring trip determination method. O

In the figure, 10 is a subscriber circuit, 11 is an equivalent circuit of a telephone, which forms a series resonant circuit,

Reference numeral 12 denotes a ring trip detection resistor (R S) which detects a telephone on-hook and a current change caused by the off-hook. Reference numeral 13 denotes a ring trip detector, and reference numeral 14 denotes a ringer generator, which generates a low-frequency AC voltage for ring trip determination. B is a switch that opens in the on-hook state and closes in the off-hook state.

The operation of the ring trip determination method shown in FIG. 1 will be described below.

The ringer generator 14 outputs an AC voltage superimposed on a low-frequency (about 20 Hz) DC voltage of 48 V. The current flowing through the ring trip detection resistor (R S) 12 is detected by the detection unit 13 as a terminal voltage, and the detection voltage is output to the output point A.

In the case of on-hook, a small AC voltage is output from output point A because the DC component is 0.

In the case of off-hook, the switch B of the subscriber circuit 10 is closed, a DC component is applied to the circuit, and the ring trip detection resistor (RS) 1 2 As a result, the AC current is superimposed on the DC component and the AC voltage is output from the output point A.

Check the voltage at point A that differs between the on-hook and the off-hook. It is possible to determine the on-hook and the off-hook by issuing.

FIG. 2 is a diagram showing an example of a conventional ring-trip determination circuit. FIG. 2A shows a ring-trip determination circuit, and FIG. The output voltage waveform at point A is shown. In FIG. 2A, 11 is a ring generator, 12 is a ring-trip detection resistor (RS), and 13 is a ring-trip circuit. It is to judge whether it is off-hook or on-hook. Reference numeral 14 denotes a detection unit that detects a voltage change between the terminals of the ring trip detection resistor (RS) 12 generated by the on-hook and the off-hook and outputs the result. It is a force. Reference numeral 15 denotes a detection circuit which detects the voltage between both ends of the ring trip detection resistor (RS) 12. ₀ 16 denotes the voltage detected by the detection circuit 15. This is a filter / integration circuit that removes the AC component and integrates, and is composed of R and C. Reference numeral 17 denotes a judgment circuit which judges on-hook and off-hook based on the output voltage of the detection unit 14.

Hereinafter, the operation of the configuration of FIG. 2A will be described.

The detection circuit 15 detects a low-frequency AC voltage generated between both ends of the ring trip detection resistor (RS) 12. Filter ♦ Integrator 16 removes AC components, integrates, and outputs.

In the configuration of the conventional detection unit 14, the filter / integration circuit 16 can sufficiently remove the AC component. However, the output voltage waveform at point A is as shown in Fig. 2B. In the filter / integration circuit 16, since the AC component flowing from the ring generator 11 cannot be completely removed, as shown in the figure, the DC component of the on-hook is zero. While a low-frequency AC voltage is output, a low-frequency AC voltage in which an AC component is superimposed on a DC component is output in the off-hook. The determination circuit 17 determines on-hook and off-hook by detecting the output voltage at point A having a different DC component voltage.

Fig. 3 is an explanatory diagram of the problem to be solved by the invention. Fig. 3A shows a case where a plurality of telephones are connected to a short line length. Fig. 3B shows a diagram of Fig. 3A. Output voltage at point A, Fig. 3C shows the output voltage at point A in Fig. 3C when a single telephone is connected to a long line.

In Fig. 3A, point A is the output point of the detection unit that detects the off-hook of the subscriber terminal (telephone in this case) and the off-hook when calling the subscriber circuit. Where 30 to 32 are telephone sets and 33 is a subscriber circuit. Figure (b) shows the output voltage at point A in Figure (a).

In Fig. 3B, ① is the on-hook period, and ② is the off-hook period. In the case of Fig. 3A, the difference between the DC voltage component between the on-hook and the off-hook and the voltage AO of the AC component in the on-hook are also large.

In Fig. 3C, 34 is a telephone and 35 is a subscriber. The circuits, 36 and 37, respectively represent the resistance components of the line. Point A is the on-hook of the subscriber terminal in the call instruction of the subscriber circuit 35, and the output point of the detection unit for detecting the off-hook.

In Fig. 3D, ③ is the period of on-hook, and ④ is the period of off-hook.

In the case of Fig. 3C, the difference between the DC component between the on-hook and the off-hook and the voltage amplitude A0 of the AC component during the off-hook period are also small.

In the case of Fig. 3A, the voltage amplitude A0 of the AC component of the on-hook is large, and in the case of Fig. 3C, the DC component is also the voltage of the AC component. The amplitude AO is also small. Conventionally, the voltage value is directly compared with the reference value to distinguish between the on-hook and the off-hook state in Fig. 3D (① and 態). (Distinction of ④) was difficult.

[Disclosure of the Invention]

An object of the present invention is to provide a ring trip determination method that can reliably detect off-hook and off-hook regardless of the conditions on the load side. On-hook and off-hook are determined by detecting the transient voltage change from off-hook to off-hook.

FIG. 4 is a diagram showing a basic configuration of the present invention, and FIG. 4A is a diagram showing a basic configuration of the first invention.

In the figure, 1 is a ring generator and 2 is a ring tree. A trip detection resistor, 3 is a ring trip circuit, and 40 is a detection section, which is similar to a conventional one. Reference numeral 41 denotes a voltage comparison unit which compares a preset threshold value with the output voltage of the detection unit 40, and differs depending on whether the output voltage of the detection unit 40 is higher or lower than the threshold value. It outputs a certain value. Reference numeral 42 denotes a state holding unit, which is determined according to the output value of the voltage comparison unit 41, and represents a case where the output voltage of the detection unit 10 is higher or lower than the threshold value. It retains the value. Reference numeral 43 denotes a state holding unit that captures, holds, and outputs the state of the state holding unit 1 in synchronization with a clock. Reference numeral 4 denotes a state holding unit that captures, holds, and outputs the state of the state holding unit 2 in synchronization with a clock. Reference numeral 4 denotes a judgment unit which compares the output (state 1) of the state holding unit 2 and the output (state 2) of the state holding unit 3 and judges the ring trip. You.

FIG. 4B shows the basic configuration of the second invention. In the drawing, the same components as those in FIG. 4A are denoted by the same reference numerals, and description thereof will be omitted. 46 is a timing section which measures the timing of the SD signal for transmitting the ringer and the clock (RT) synchronized with the ringer cycle, and Generate an operation synchronization signal. Reference numeral 47 denotes a threshold storage unit, which captures, holds, and outputs the output of the voltage comparison unit 41 in synchronization with the operation synchronization signal generated by the timing unit 46. . 4 8 is the noise filter section This is to eliminate the noise of the output of the judgment unit. The determination unit 45 in the second invention compares the output of the state storage unit 2 with the output of the threshold value storage unit and determines the ring trip.

[Brief description of drawings]

Fig. 1 is an explanatory diagram of the ring trip judgment method, Fig. 2 A is the conventional ring trip judgment circuit, and Fig. 2 B is the output voltage waveform at point A of the detection unit 14. Figure 3A shows that when multiple telephones are connected to a short line length,

Figure 3B is the output voltage at point A in Figure 3A,

Figure 3C shows that a single telephone is connected to a long track.

Fig. 3D is the output voltage at point A in Fig. 3C,

FIG. 4A is a diagram showing a basic configuration diagram of the first invention, FIG. 4B is a diagram showing a basic configuration diagram of the second invention, and FIG. 5 is according to the first embodiment of the first invention. Ring trip judgment circuit,

FIG. 6 shows a timing chart of the first embodiment of the first invention.

FIG. 7 shows a ring trip determination circuit according to a second embodiment of the first invention,

FIGS. 8A to 8H are diagrams showing an example of a truth table of a ring trip determination circuit according to a second embodiment of the first invention. FIG. 9 shows a ring trip determining circuit according to one embodiment of the second invention,

FIG. 10 is a diagram showing a time chart of one embodiment of the second invention.

[Best mode for carrying out the invention]

FIG. 5 is a diagram showing a ring trip determination circuit according to the first embodiment of the first invention.

In the figure, reference numeral 50 denotes a voltage comparator, which compares the output voltage (V s) of the voltage detector with the threshold voltage (V th) and outputs an output value of 1 when the output voltage of the voltage detector exceeds the threshold. And outputs an output value of 0 if the threshold is not exceeded.

51 is a state holding unit 1 which is composed of a D flip-flop (D-FF), and is reset asynchronously by the output value 1 of the voltage comparison unit 50. Then, output Q 1 = 0. Further, D-FF (51) outputs the D input value as Q1 in synchronization with the clock (RT) input to the clock input CP. D — FF The input value of F (5 1) is fixed to his 1 of V c c.

Reference numeral 2 denotes a state holding unit 2 (Latch 2), which is constituted by a latch and is synchronized with a clock (negation of RT) input to a clock input CP. The output value Q 1 of the state holding section 51 is output to Q 2.

5 3 is a state holding unit 3 (Latch 3), In synchronization with the clock (negation of RT), the output value Q 2 of the state holding unit 52 is taken in and output to Q 3.

Numeral 5 4 is a judgment unit which inputs and compares the output value Q 2 of the state holding unit 2 (5 2) with the output value Q 3 of the state holding unit 53, judges the logic thereof, and makes a ring. It performs trip judgment.

Numeral 5 5 denotes an inverter for inverting a clock (RT) which is a synchronization pulse of the state holding unit 2 (52) and the state holding unit 3 (53). .

Reference numeral 56 denotes a clock generation unit which generates a clock (RT) from the ringer signal from the ringer generator 1.

FIG. 6 is a diagram showing a time chart according to the first embodiment of the first invention.

In the figure, (a) is the ringer voltage, which is the voltage output from the ringer generator 1. (B) is a clock (RT) generated by the clock generator 56 in synchronization with the ringer voltage (a). (C) is the threshold voltage (V th) of the voltage comparator 50. (D) is the output voltage (V s) of the voltage detection unit, which indicates the output voltage of the on-hook voltage and the off-hook voltage (after OFFHOOK in the figure). (E) is the output voltage of the voltage comparison unit 50. (Ί) is the output Q1 of the status holding unit 1 (D-FF). (G) is the output Q 2 of the state holding unit 2 (Latch 2). (H) is the output of state holding unit 3 (& 1 11 11 3) The operation of the first embodiment of the first invention shown in FIG. 5 will be described with reference to FIG.

The clock generator (56) generates a clock (RT) from the ringer voltage (a) force. Then, D — FF (51), L acth 2 (52), and Latch 3 (53) output the value of each D input in synchronization with the clock (RT). Output to l, Q 2, Q 3.

D — FF (51) captures the fixed value Vcc of the D input, value 1 which is synchronized with the rising edge of the clock (RT), and outputs it as output Q1. Yes ((1)). In the case of the voltage detector output voltage (V s), which is the on-hook (before OFFHOOK in Fig. 3), and the voltage of the output, the voltage is lower than the threshold voltage V th (c). The output voltage (e) of the comparison section 50 also remains at the value 0. At this time, Latch2 and Latch3 output a value 1 as an output Q2 in synchronization with the clock (negation of RT: falling) ((2)).

Therefore, in the on-hook state, the input values Q 2 and Q 3 of the determination section 54 are both the value 1 and the ring trip is not performed ((3)). .

Next, in the case of the waveform port of the output voltage of the voltage detection unit (V s), the waveform port is below the threshold voltage V th (c), and the output voltage (e) of the voltage comparison unit 50 is the value 0 Latch 2 synchronizes with the clock (negation of RT) -The value 1 (the state of the waveform port) of the output Ql from the FF (51) is taken and output to the output Q2. ((2)) The voltage comparison unit 50 When the incoming waveform of the output voltage (V s) of the voltage detection section (V s) exceeds the threshold voltage V th (c), the output voltage (e) is set to the value 1 only during the period when the threshold voltage V th (c) is exceeded ((4)). On the other hand, the D-FF (51) keeps outputting the value 1 as the output Q1 in synchronization with the clock (RT) ((4)), and the output voltage (e) D — FF (5 1) is reset and the value 1 of the output Q 1 up to now is inverted to the value 0 ((5)) 0

Latch 2 synchronizes with the next clock (negation of RT), fetches the value 0 of output Q 1 from D-FF (51), which is the state of waveform 8, and outputs Q Output as 2 ((6)). At the same timing, Latc 3 takes the value 1 (the state of the waveform port) of the previous output value Q 2 from Latch 2 and outputs it to output Q 3 ((7)) O

As a result, the judgment unit 54 inputs the value 0 (the state of the waveform C) of the output Q 2 of Latch 2 and the value 1 (the state of the waveform port) of the output Q 3 of the Latch 3 and performs logical judgment. Output 0 and detect off-hook ((8))

Therefore, according to the configuration of the first embodiment of the first invention, since the on-hook and the off-hook are converted into different state values and detected, the voltage is reduced. Even when the detector output voltage (V s) is small, the on-hook Off-hook can be determined.

On the other hand, in the case of the waveforms of the voltage detection unit output voltage (V s) c, 2, e,..., All the waveforms exceed the threshold voltage V .th (c). Both 2 and Q 3 have the value 0, and the same state is maintained, so that the output of the judgment unit is restored to the value 1 ((9)).

FIG. 7 is a diagram showing a ring trip determination circuit according to a second embodiment of the first invention. In the second embodiment, a plurality of threshold voltages are provided, and when an output voltage exceeding a certain predetermined number of threshold voltages appears, an off-hook is detected.

In the figure, reference numeral '71 denotes a voltage comparator (multiple comparator), which is composed of a plurality of comparators having any one of threshold voltages Vth1 to Vth6. The threshold voltage V th1 to V th6 are compared with the output voltage V s of the voltage detection unit, and the output differs depending on whether the output voltage V s of the voltage detection unit is higher or lower than the threshold value. The value is output for each threshold value.

Reference numeral 7 2 denotes a 6-bit D flip-flop (D-FF), which is connected to the reset input terminals RA to RF, respectively, and is connected to the threshold V of the multi-computer 71. The comparison results of thl to V th6 are input, and the corresponding outputs Q1A to Q1F are reset. D — The D input of the FF (72) is fixed at a value of 1 which is Vcc. 7 '3, — is Latch 2 which is composed of a 6-bit latch and outputs D 1 FF (72) output Q 1 A to QIF to D 2 A to D, respectively. It is input to the 2F input and output to outputs Q2A to Q2F in synchronization with the clock (negation of RT).

74 is composed of a 5-bit latch as indicated by &1; (: 113), synchronized with the clock (negation of RT), and latch 2 (73). The outputs Q2B to Q2F are taken into the inputs D3B to D3F, respectively, and output to the outputs Q3B to Q3F.

Numeral 75 denotes a judgment unit, which is composed of gates 75-1 to 75-5 and an OR gate 75-6. Gates 7 5 — 1 to 7 5 — 5 are the outputs of Latch 3 (7 4) connected to them (when ¾ 3 8 to (¾ 3? 7 3) Output Q 2 B to Q

2 This is to invalidate the value of F (set the value to 0). In the second embodiment shown in FIG. 7, when the threshold voltage of the continuous waveform of the output voltage V s of the voltage detection unit differs by 2 or more, each output Q of L t c 3 is regarded as off-hook.

3C to Q3F are the corresponding outputs of Latch2, the gates of Q2C to Q2F, and the corresponding outputs Q2B to Q2E, respectively, of the upper threshold. The gates are designed to be erection-free. OR gates 75-6 output the OR logic (RTP) of each input section (in). 76 is an evening, which negates the logic of the clock (RT).

The relationship among the thresholds V th 1, V th 2, V th 3, V th 4, V th 5, and V th 6 of the multi-computer 71 in FIG. 7 is V thl> V t li 2> V th 3 > V th 4> V th 5> V th 6

In the configuration of FIG. 7, D-FF (72), Latch corresponding to each output of the multi-computer 71

The operations of 2 (73) and .Latch 3 (74) are the same as those in FIGS. 5 and 6. Then, in the seventh embodiment, the outputs Q 2 B to Q 2 F of the Latch 2 (73) are output from the output Q 2 of the Latch 3 (7 4).

When the value of 3 B to Q 3 F is 1, the corresponding bit is invalidated (value is set to 0), and 0 R gate 75 — 6 outputs Q 2 A output and gate 75 — The only difference is that the value obtained by ORing the outputs of 1 to 7 5-5 is output.

FIGS. 8A to 8H show examples of truth tables of the ring trip determination circuit according to the second embodiment of the first invention. 8A to 8H, QxA to QxF denote Q2A to Q2F and Q3A to Q3F, respectively. L 2 is the output of L a t ch 2, L 3 is the output of L a t ch 3, O R in is the OR output 7 5 — 6 input, 1¾? Is the output of the output 755-16.

The truth table in Fig. 8A shows the output voltage of the voltage detector. 1 δ

When the (V s) force is greater than V thl, the truth table in FIG. 8 shows that when the (V s) force is less than V th6, the truth table in FIGS. The value table is (V s)

It shows the case where it is between Vth5.

As shown in the truth table of FIG. 8A, in the present embodiment, when V s force is larger than V th1, RTP is set to 1 and the subscriber is turned off. Is considered to have been clicked. In addition, as shown in the truth table of Fig. 8B, V s is

If less than V th 6, the subscriber is considered on-hook. If the V s force is between V th1 and V th6, the judgment is made based on the difference between the outputs of Latch 2 and Latch 3 (V s and L at time t 1 held by Latch 3). Compare V s at the later time t 2 held by atch 2). If the output of Latch 2 is larger than the output of Latch 3 by 2 bits or more (when V s changes greatly from time t 1 to time t 2), the subscriber It is regarded as the off-hook (truth value table for D and F in Fig. 8). Also, when the output power of Latch 2 is smaller than or equal to the output of Latch 3, or when it is larger by one bit (V s at time t2 from time t1) Is small, or if Vs has no change at time t1 and time t2, or if the change is small), the subscriber remains on-hook. (Fig. 8 F, G, H) According to the second embodiment of the first invention, even when it is difficult to determine whether the output voltage (V s) of the voltage detection section is on-hook or off-hook, the plurality of threshold voltages V By providing th1 to Vth6, by detecting the magnitude of the change, the on-hook and the off-hook can be reliably determined.

FIG. 9 is a diagram showing a ring trip determination circuit according to one embodiment of the second invention. In the figure, the same components as those in FIG. 7 are denoted by the same reference numerals.

In the figure, reference numeral 91 denotes a timing circuit, which is composed of D—FF 91—1, 91—2, NAND gate 91—3, and not gate 91—4. It is. D —; FF 91-1 fetches and outputs the SD signal instructing ringer transmission from the exchange in synchronization with the clock (RT) synchronized with the ringer cycle. — FF 91-2 also captures this output in synchronization with the clock (RT) and outputs the inversion. After passing both the outputs of D-FF91-1 and D-FF91-1 through the NOT gate 91-3, the inverted signal is output. As a result, the signal is obtained by differentiating the SD signal by one period.

Reference numeral 92 denotes a threshold storage unit, which is composed of a register power, and takes the output of the voltage comparison unit 71 in synchronization with the operation synchronization signal generated by the timing generation circuit 91. It stores, stores, and outputs.

9 3 is a gate, which is a reference voltage of the voltage comparator 71. 1

The outputs of the comparators corresponding to V th2 to V th6 are controlled by the timing circuit 91 (in synchronization with the outputs of the not gates 91 to 3). It is input to the resets RB to RF of the threshold value storage section 92 via the gate 93.

Reference numeral 94 denotes a noise filter section, to which the output of the OR gates 75 to 6 of the judgment section 75 is input to the DA force. D—FF 94—1 and D—FF 94—1 It is composed of an AND gate 94-2 that takes the logical sum of the output Q of the OR and the OR gate 75-6, and eliminates the noise of the output of the judging unit 75.

In the figure, (a) is the ringer voltage, which is the voltage output from the ringer generator. (B) is an SD signal for sending a ringer sent from the exchange. (C) is a clock (RT) generated in synchronization with the ringer voltage (a). (D) is an operation synchronization signal obtained by differentiating the SD signal generated by the timing circuit 91 for one cycle (for example, 50 ms). (E) is the operation synchronizing signal of the gate 93, and the gate is open only for the time of the value 1. (F) is a plurality of threshold voltages V th1 to V th6 of the voltage comparison unit 71. (G) is the output voltage of the voltage detector (

V s), which indicates the output voltage of the on-hook voltage and the off-hook voltage (after OFFHOOK in the figure). 1 δ (H) shows the output voltage for each threshold of the voltage comparator 71 (multi-comparator), and the numbers in the figure indicate the case where the output of the voltage detector exceeds any of the thresholds. Yes, ① is when the voltage detector output voltage V s exceeds only the threshold V th6, ② is when the voltage detector output voltage V s exceeds the threshold V th5, 6, and ③ is the voltage detector output If the voltage V s exceeds the threshold value V th4, 5, 6, then ♦. (I) shows a plurality of outputs (^ 1 to Q 1 F) of D-FF 1 (72). In the figure, ① shows only output Q 1 F, and ② shows outputs Q 1 E and Q 1. F and ③ indicate that outputs Q 1 D to Q 1 F, ··· output <reset output (j) Outputs Q 3 B to Q 3 F of threshold storage unit 92 In the figure, ① shows the reset output of only output Q 3 F, ② shows the reset output of outputs Q 3 E and Q 3 F, and ③ shows the reset output of outputs Q 3 D to Q 3 F, ··· (K) shows the outputs Q 2 A to Q 2 F of Latch 2, in which (1) is the output Q 2 F only, (2) is the output Q 2 E and ③ is the output Q 2 D to Q 2. The reset output of F, ..... (1) is 0 W which is the output of the judgment unit 75, (n) is the D-FF2 (94) of the noise filter unit 94. -The output of 1) and the output of AND gate 94-2

The operation of the embodiment of the second invention shown in FIG. 9 will be described with reference to FIG.

The ringer voltage (a) is generated by the SD signal (b) from the exchange ((1)), and the clock RT (c) is generated from the ringer signal (a). Is generated. In the second invention, when a call is received by the subscriber, a timing operation synchronizing signal (d) is created by differentiating the ringer signal) by one period by the timing circuit 91. ((2)). In synchronization with this operation synchronization signal (d), the threshold storage unit 92 takes in the fixed value of Vcc of the D input, and sets all outputs Q3B to Q3F to the value 1 ((3 )). At the same time, the gate 93 is kept open for a certain period. When the gate 93 is in the open state, the voltage comparator 71 outputs the threshold V th6 because the waveform of the second arriving output voltage V s exceeds the threshold voltage V th6. The output (h) is set to a value of 1 only during the period that exceeds the threshold voltage Vth6 from the comparator ((4)). As a result, in the threshold storage section 92 in which all the outputs Q 3 B to Q 3 F have a value of 1, only the output Q 3 F is reset to a value of 0 ((6)). The value storage unit 92 stores the waveform port as a threshold value for off-hook determination. At the same time, the output Q 1 F is reset to the value 0 at D — FF 1 (72) ((5)). Thereafter, the determination unit 75 compares the threshold value (waveform port) from the threshold value storage unit 92 with the subsequent waveforms of the voltage detection unit output voltage Vs C, 2, E,. Make a decision.

Here, the reason why the first waveform is not taken as the reference threshold value for the off-hook determination, but the second waveform port is taken as the reference threshold value is as follows. In an actual subscriber call, an inrush current flows due to the influence of the capacitance of the telephone, etc. In some cases, the signal may appear as its output through the detection unit 40, and only the first waveform may become a large signal, causing a ring trip by mistake. Power. In this embodiment, the SD signal is differentiated by one cycle (5 Oms) to be used as an operation synchronization signal. However, the present invention is not limited to this, and an appropriate value may be set. .

D-FF 1 (72) takes in the fixed value Vcc in synchronization with the next incoming clock RT, and changes the output Q1F from the value 0 to the value 1 ((7) ). In the case of the third waveform C, any of the threshold values Vth1

Since the voltage does not exceed V th 6, all the outputs of the voltage comparison unit 41 have a value of 0, and all the outputs Q 1 A to Q 1 F of D — FF 1 (72) and all the outputs Q 2 of Latch 2 A to Q 2 F are held at the value 1. In the judgment section 75, the gates 75 14 and 75 — 5 are invalidated by the output Q 3 F which is the value 1 of the threshold storage section 92 and the OR gate 75 5 — The output of 6 has the value 1 ((8)). Therefore, the output of AND gate 94-2 is 1 ^? Has a value of 1 and is not considered an off-hook ((9)).

Since the second waveform of the output voltage V s of the fourth voltage comparison section exceeds the threshold value V th3 to V "t li 6, the threshold voltage V th3 to V t li 6 of the voltage comparison section 71 is not used. The output of the 、 / ° / 夕 signal becomes 1 and the output of D—FF 1 (72) Q 1 C: to Q 1 F and the output of Latch 2 (73) Q 2 c to Q 2 F Change both to the value 1 and then to the value 0 (αο), αΐ) ) o In the judgment section 75, the gates 75-4 and 7

5 — 5 is invalid, so L a t. Ch 2 (7 3

) Output Q 2 E and Q 2 F values 0 are OR gates 7 5 —

The gate that is not input to 6, but not invalidated 7 5-3 force, the output 0 of the output Q 2 D of L a t ch 2 (7 3)

The OR gates 75-6 are entered, and the output of the decision unit 75 becomes a value of 0 ((12). D-FF 2 (94-1) is the next rising edge of the clock). Until the output goes down, the previous output value 1 is retained, and the AND gate 94-2 does not ring-trip (aa>).

Next, in the same manner as in the case of the waveform 2 of the output voltage Vs, the fifth output waveform Vs of the output voltage Vs resets the outputs Q 1 D to Q 1 F of D—FF 1 (72). Then, in synchronization with the next clock (negation of RT), the outputs Q2D to Q2F of Latch 2 (73) change to the value 0 ((14), s). Therefore, at the falling edge of the clock (RT), the output value Q of D — FF 2 (94 — 1) and the output value 0 of the decision unit 75 are AND gated at the fall of the clock (RT). 4-2 becomes valid, the output RTP changes to the value 0, and the ring trips ((16)).

In other words, the noise filter unit 94 reads the output of the judgment unit 75 twice, and if the data continues for two or more clock cycles, it is regarded as valid. It is output to the subsequent stage as a grip signal RTP. Further, in the second invention, the voltage value serving as the threshold and the incoming voltage Since the values are compared, the RTP is always kept at the value 0 in the off-hook state (to the waveform, to, ...).

As described above, according to the present invention, the on-hook and the off-hook are determined based on the state transition of the ring-trip detection voltage, so that the line length and the terminal to the subscriber terminal are determined. A reliable ring trip can be determined irrespective of the load conditions such as the number of unions. Even if the state transition of the output of the ring trip detection circuit is gradual, since the threshold value is compared at the time of on-hook / off-hook, the ring is reliably connected. Trip operation can be realized, and the output is read twice, which eliminates erroneous trips.

[Industrial applicability]

INDUSTRIAL APPLICABILITY The present invention can be applied to detecting off-hook when calling a terminal device such as a telephone connected to a telephone line.

Claims

The scope of the claims

1. A ring trip determination circuit that detects on-hook and off-hook of a subscriber terminal when calling a terminal device connected to a telephone line.

A ring trip detection resistor (2) connected in series to the ringer generator (1) and detecting a change in the current value due to the on-hook and the off-hook;

A detection section (40) for detecting a voltage change across the ring trip detection resistor (2);

A voltage comparison unit (41) that compares the voltage output by the detection unit (40) with a threshold value and outputs different values depending on whether the threshold value is large or small.

A state holding unit 1 (42) for holding and outputting different state values according to different output values of the voltage comparison unit (41);

In synchronization with the clock, at least two status values output from the status holding unit 1 (42) are captured, held and output by the status holding units (43, 44). ,

A state determination unit (45) for comparing state values of the state holding units (43, 44);

The judging section (45) compares the state values of the state holding sections (43, 44) to obtain different values at different times detected by the ring trip detecting resistor (2). Judgment of voltage change and detection of off-hook and off-hook of terminal equipment A ring trip judgment circuit characterized by the following features.

2. In Claim 1,

The state holding units (43, 44) synchronize with the clock, fetch the state values of the state holding unit 1 (42), hold and output the state values of the state holding unit 2 (43). ), And a state holding unit 3 (44) that fetches and holds the state value output from the state holding unit 2 (43) in synchronization with the clock, and a force.

The judgment section (45) detects the ring trip detection resistance (2) by comparing the state values of the state holding section 2 (43) and the state holding section 3 (44). A ring trip determination circuit characterized in that it detects voltage changes at different times and detects on-hook and off-hook of a terminal device.

3. In Claim 1 and Claim 2,

The voltage ratio section (41) is composed of multiple comparators having a plurality of different thresholds.

The state holding unit 1 (4 2) holds a state value determined by a plurality of output values of the multi-computer, and the state holding unit 2 (4 3) holds a plurality of the state holding units 1 (4 2). The state holding unit 3 (44) fetches and holds the state values of the state, and fetches and holds a plurality of state values output from the state holding unit 2 (43). Is the state holding part (4 3 By comparing the state values of (4) and (4), the voltage changes at different times detected by the ring trip detection resistor (2) are determined, and the terminal device is turned off or on. A ring trip determination circuit characterized by detecting locks and off-hook.

4. In claim 3,

The judgment unit (45) determines a state value corresponding to a state in which the output value of the state holding unit 3 (44) exceeds the threshold of the voltage comparison unit (41) when the output voltage of the detection unit (40) exceeds the threshold value. In the case of holding, the output value of the state holding unit 2 (43) determined by the corresponding gaze value is invalidated,

The judgment unit (45) compares the values of the state holding unit (2) (3) and the state holding unit (3) (44) with each other. A ring-trip determination circuit that detects when a large voltage change occurs and determines whether or not there is an off-hook or not.

5. In claim 3,

If the output voltage of the detection section (40) exceeds the maximum threshold value in the multi-comparator, the judgment section (45) sets the output value of the state holding section 3 (44) to the output value. A ring trip determination circuit characterized in that the off-hook is determined independently of the other.

6. In the ring trip judgment circuit for detecting the off-hook and off-hook of the subscriber terminal when calling the terminal device connected to the telephone line,

A detection unit (40) for detecting a voltage change between both ends of the ring trip detection resistor (2);

A voltage comparison unit (41) that compares the voltage output by the detection unit (40) with a threshold value and outputs a different value [when the threshold value is large and when the threshold value is small]

State holding units (42, 43) which hold different state values in accordance with different output values of the voltage comparison unit (41) and output in synchronization with a clock;

At a predetermined timing, the threshold value storage section captures and holds the output state value of the voltage comparison section (41) as a reference state value, and outputs it in synchronization with the clock. (4 6) and

The state holding unit (42, 43) includes a state determination unit (45) for comparing the state value of the threshold storage unit. The determination unit (45) is a state storage unit (43, 44). ) Is compared with the state value of the threshold value storage unit to determine the difference detected by the ring trip detection resistor (2). A ring trip determination circuit characterized by detecting a voltage change at a certain time and detecting on-hook and off-hook of a terminal device.

7. In claim 6,

The input value storage section (46) is a timing section (47) for generating a timing after a predetermined time has elapsed from the start of the generation of the ringer signal. In synchronization with the clock, the state value of the output of the voltage comparison section (41) is taken in and held as a reference state value, and output in synchronization with the clock. Ring trip judgment circuit.

8. In claim 7,

The voltage comparison section (41) is composed of multiple comparators having a plurality of different thresholds.

The state holding unit 1 (42, 43) holds a state value determined by a plurality of output values of the multi-comparator, and the threshold value storage unit (46) stores the state value of the voltage comparison unit (41). A plurality of status values are captured and held as reference status values, and the judgment unit (45) is used as a reference for the status values of the status holding units (43, 44) and the threshold value storage unit (46). By comparing the state values, the voltage change detected by the ring trip detection resistor (2) is determined, and the on-hook and off-hook of the terminal device are detected. Ring trip judgment circuit characterized by:

9. In claim 8,

The judging unit (45) is a state value corresponding to a state in which the output value of the state holding unit 3 (44) exceeds the threshold of the voltage comparing unit (41) when the output voltage of the detecting unit (40) exceeds the threshold value. Is held, the output value of the state holding unit 2 (43) determined by the corresponding threshold value is invalidated.

The judging section (45) compares the values of the state holding section 2 (3) and the state holding section 3 (44) with the result that both ends of the ring-trip detection resistor are exposed. A ring trip determination circuit that detects when a large voltage change occurs and determines whether or not the circuit is off-hook.

1 0. In claim 9,

If the output voltage of the detection section (40) exceeds the maximum threshold value in the multi-computer, the judgment section (45) determines the output value of the state holding section 3 (44). A ring trip determination circuit that determines off-hook.

1 1. In claim 6,

A noise filter section (48) for holding a continuous output of the determination section (45);

The judging section (45) continuously changes the on-hook state. A ring trip judgment circuit characterized in that it is regarded as off-hook only when detected.