JPH089023A - Method for detecting on-hook/off-hook in exchange - Google Patents

Abstract

PURPOSE:To avoid deterioration in speech quality by detecting an on-hook state or an off-hook state at an extension terminal depending on the result of comparison between a specific reference voltage and a terminal voltage of the extension terminal. CONSTITUTION:A constant voltage diode 23 of a hook detection section 26 generates a reference voltage Vref stabilized into a Zener voltage by impressing a DC power supply voltage V,, to its cathode terminal via a resistor 24. The reference voltage is set to be a nearly intermediate voltage level between the terminal voltage of a slave set in the case of hook-on and a terminal voltage when the slave set 12 is hooked off. Furthermore, the reference voltage Vref is impressed to an inverting input terminal of a comparator 25 and a terminal voltage Vp of the slave set 12 provided with a circuit impedance ZR2 is impressed to a noninverting input terminal to detect a state of on-hook or off-hook at the slave set 12 depending on the result of comparison. Thus, mismatching of the circuit impedance between a master set and the slave set is eliminated to avoid deterioration in speech quality.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-hook / off-hook detecting method for detecting an on-hook or off-hook state in an extension terminal in a switchboard.

[0002]

2. Description of the Related Art When controlling a plurality of telephone terminals in an exchange, for example, when an incoming call arrives, the exchange detects the on-hook or off-hook state of an extension terminal to be connected, and the ringing tone is output according to the detection result. Is generated at the extension terminal to be connected, or a signal indicating busy is sent back to the calling side. When a ringing tone is generated at the extension terminal to be connected, the off-hook at the extension terminal is detected to form a call path with the extension terminal to be connected to make a call. Transition to the state.

FIG. 4 is an equivalent circuit diagram showing a configuration of a conventional on-hook / off-hook detecting method for detecting the on-hook or off-hook state of an extension terminal. In the figure, reference numeral 1 is a DC bias power supply, ZR1, for enabling a call.
Is a circuit impedance on the exchange side (hereinafter, referred to as a master), ZR2 is a circuit impedance on the extension terminal side (hereinafter, referred to as a slave), and RH is a hook detection resistor for on-hook or off-hook detection. This hook detection resistance RH
Are connected in series to the circuit impedance ZR1 on the master side and the circuit impedance ZR2 on the slave side.

FIG. 5 shows the hook detection resistor RH shown in FIG.
3 is an electric circuit diagram showing a circuit configuration corresponding to FIG. In the figure, R1 is a shunt resistor for detecting a current when off-hooked on the slave unit side, and a voltage drop is generated across the shunt resistor R1 by the current flowing when off-hooked. D1 and D2 are constant voltage diodes, which keep the amount of voltage drop generated across the shunt resistor R1 constant. C1 is a capacitor for bypassing the AC signal, and R2 is a resistor for limiting the value of the current flowing to the light emitting diode side of the photocoupler Po.

The current when off-hooked on the slave unit side is converted into the voltage drop amount of the shunt resistor R1, and the current corresponding to the potential difference between both ends of the shunt resistor R1 flows into the light emitting diode of the photocoupler Po and the light emitting diode. To drive. Then, the phototransistor of the photocoupler Po is turned on / off, and an off-hook or on-hook detection signal on the slave side is taken out from the collector terminal of the phototransistor and output to a microcomputer (not shown) on the master side. Identifies off-hook or on-hook by this detection signal.

[0006]

Since the conventional on-hook / off-hook detection method is constructed as described above,
As shown in FIG. 4, the circuit impedance on the slave side when the slave side is viewed from the master side is (RH + ZR2), and the circuit impedance on the master side when the master side is viewed from the slave side is (R
H + ZR1), and unless the RH is set to zero, the circuit impedance matching cannot be established and the circuit impedance mismatch occurs, resulting in an increase in the side sounds that can be heard by the user and a deterioration in the call quality. was there.

The present invention has been made to solve the above problems, and an on-hook / off-hook detection method capable of avoiding the deterioration of the communication quality by eliminating the mismatch of the circuit impedance between the master unit and the slave unit. The purpose is to provide.

[0008]

An on-hook / off-hook detection method for an exchange according to the present invention is designed so that, when connecting between extension terminals or connecting to an outside line, each of the exchanges responds to the on-hook or off-hook state of the extension terminal. An on-hook / off-hook detection method for detecting the on-hook or off-hook state of the extension terminal when controlling the extension terminal, the terminal voltage and the off-hook state of the extension terminal when the extension terminal is on-hook. A terminal voltage corresponding to a difference in circuit impedance on the extension terminal side when the extension terminal is in an on-hook state or an off-hook state. Is detected and the terminal voltage is compared with the reference voltage, And detecting the on-hook or off-hook condition in the terminal.

[0009]

The on-hook / off-hook detection method in the exchange according to the present invention comprises a reference voltage set between the terminal voltage of the extension terminal in the on-hook state and the terminal voltage in the off-hook state. Voltage and the terminal voltage on the extension terminal side are compared, the on-hook or off-hook state on the extension terminal side is detected according to the comparison result, and it is possible to omit the hook detection resistance, and the master unit and the slave unit. It eliminates the mismatch of circuit impedance between them and avoids the deterioration of the communication quality due to the increase of sidetone.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a call circuit diagram including a master unit and a slave unit to which the on-hook / off-hook detection method in the exchange of this embodiment is applied. In the figure, 11 indicates a master unit and 12 indicates a slave unit. The base unit 11 and the handset unit 12 are connected via a modular jack 13. Reference numeral 14 indicates the circuit impedance ZR2 of the slave unit 12. Reference numeral 15 is a ringer sound source that is a source of ringing tone, 16 is a DC bias power source for ringing tone, RR is a protection resistor for overcurrent that flows when a short circuit occurs, 17 is a source of transmission sound, and 18 is transmission sound. It is a DC bias power supply for sound. Reference numeral 19 indicates the circuit impedance of the parent device side 11, and has the circuit impedance of ZR1 when viewed from the child device side 12.

Reference numerals 21 and 22 are relay contacts controlled by a microcomputer (not shown) on the base unit 11 side, and they switch between the ringer sound source 15 and the transmission sound source 17. Reference numeral 23 is a constant voltage diode, which is a DC power supply Vc
By applying c to the cathode terminal of the resistor 24 via the resistor 24, the reference voltage Vref stabilized to the Zener voltage is generated. The reference voltage Vref is a terminal voltage of the slave unit when the slave unit 12 is on-hook (for example, ZR2 has an AC impedance of 3 kΩ or more when on-hook) and a terminal voltage when the off-hook (for example, ZR2 is an AC impedance of 300 when off-hook).
Ω or less) is set to a voltage level approximately in the middle. Reference numeral 25 is a comparator, to which the reference voltage Vref is applied to the inverting input terminal, and the terminal voltage Vp of the slave unit 12 having the circuit impedance ZR2 is applied to the non-inverting input terminal. The constant voltage diode 23, the resistor 24, the comparator 25, and the like constitute a hook detection unit 26.

FIG. 2 shows the master unit 11 and the slave unit 1 when the relay contacts 21 and 22 are switched to the transmission sound source 17 side.
2 is an equivalent circuit of a communication path composed of 2 and parts that are the same as or equivalent to those in FIG. 1 are assigned the same reference numerals.

Next, an on-hook / off-hook detection method in the exchange of this embodiment will be described with reference to FIG. 2 (a) is an equivalent circuit in the call mode, FIG. 2 (b).
Is an equivalent circuit in the Ringer mode. In these equivalent circuits, V is the voltage of the DC bias power supply 18 for the transmission sound in FIG. 1 and indicates the voltage of the DC bias power supply 16 for the ringing sound. Vr represents the AC voltage of the ringer sound source 15 that is the source of the ringing tone in FIG. In the above equivalent circuit diagrams 2 (a) and 2 (b), specific values actually used will be described. V as an example of the value
= 60 (V), Vr = 75 (Vrms), RR = 3.9
(KΩ). ZR1 shall consist of the balance network shown in FIG.2 (c). That is, in a balance network in which the resistors R1 and R2 are connected in series and the capacitor C is connected in parallel to the resistor R1, R1 = 680
(Ω), R2 = 200 (Ω), and C = 0.1 (μF). In addition, since the ZR2 in the call mode of FIG. 2A only needs to consider the DC characteristic, the circuit impedance ZR2 (ON) = ∞ (actually about several megohms) when on-hook and the circuit impedance ZR2 when off-hook.
(OFF) = 300 (Ω), while circuit impedance ZR2 (ON) = 3 (KΩ) during on-hook and circuit impedance ZR2 (OFF) = 300 (Ω) during off-hook in the communication mode of FIG. ). If the above values are taken, it will be as follows. In the call mode, the terminal voltage Vp of the handset 12 is Vp = V × ZR2 / (ZR1 + ZR2), so that Vp (ON) ≈V when on-hook and Vp (OFF) ≈0.254V when off-hook. On the other hand, in the ringer mode, the terminal voltage Vp of the child device 12 is Vp = (V + Vr) {ZR2 / (RR + ZR2)}, so Vp (ON) ≈0.435 (V
+ Vr), Vp (OFF) ≈0.071 when off-hook
4 (V + Vr). Here, focusing only on the peak value of the Vr AC signal, Vp (ON) ≈26.1 ± 3
2.6 (V), Vp (OFF) ≈4.29 ± 5.36
Since it is (V), the peak value of the positive voltage is Vp (ON) ≈58.
7 (V), Vp (OFF) ≈9.65 (V). The above is summarized in Table 1 as follows.

[0014]

[Table 1] (Maximum positive voltage of terminal voltage Vp)

From Table 1, in order to detect the on / off hook, the reference voltage Vref of the comparator 25 is set to 58.
It may be set between (V) and 10 (V). However, in reality, the impedance of the cable connecting the terminals exists, and the off-hook voltage rises.
Between 0 (V) and 30 (V) (for example, Vref = 4
It is desirable to set it to 0 (V).

Next, another embodiment will be described in which the on-hook / off-hook detection method in the exchange of the present invention is used in a call circuit including a master and a plurality of slaves.
FIG. 3 is a call circuit diagram in which a plurality of slave units, in this case, four slave units are connected to the master unit. 3 in the figure
1 is a switching control block for the handset TEL1, 32
Is a switching control block for the handset TEL2, 33 is a switching control block for the handset TEL3, and 34 is a switching control block for the handset TEL4. The switching control blocks 31, 32, 33, 34 all have the same circuit configuration.

A switching control block 3 includes 31a and 31b.
1 is an extension / outside line switching relay contact for the slave unit TEL1 and is controlled by a microcomputer (not shown). Reference numeral 31c is a hook detector, which has the same circuit configuration as the hook detector 26 shown in FIG. 31
Reference numeral d denotes an extension switching relay contact for switching the extension between the slaves and generating a ringing sound, and an extension / outside switching relay contact 31.
Like a and 31b, it is controlled by a microcomputer (not shown). Reference numeral 35 is a ringer sound source for generating a ringing tone, and 36 is a cordless handset T when extension switching is performed.
EL1 constant current source, 37 similarly constant current source for slave unit TEL2, 38 similarly constant current source for slave unit TEL3, 39
Is also a constant current source for the slave unit TEL4. Reference numeral 40 is a coupling capacitor for the slave unit TEL1 for cutting off a direct current component, 41 is a coupling capacitor for the slave unit TEL2 similarly, 42 is a coupling capacitor for the slave unit TEL3 similarly, 43 is a slave unit similarly. This is a coupling capacitor for TEL4. Reference numeral 44 is an extension switching crosspoint switch circuit controlled by a microcomputer (not shown), and 45 is a tone service sound source.

Also in this embodiment, the hook detecting section 31 is a circuit constituting section for realizing the on-hook / off-hook detecting method in the exchange of the present invention, and the operation thereof has been described in the above-mentioned embodiments, and therefore will be omitted. The hook detector 3
The constant voltage sources 16 and 18 in 1c can be constant current sources 36 to 39.

[0019]

As described above, according to the present invention, it is possible to detect on-hook / off-hook in an exchange without using a hook detection resistor. Therefore, the circuit between the master unit and the slave unit by the hook detection resistor can be used. There is an effect that the impedance mismatch is eliminated, the side sound due to the circuit impedance mismatch is suppressed, and the communication quality is improved.

[Brief description of drawings]

FIG. 1 is a communication circuit diagram including a master unit and a slave unit to which an on-hook / off-hook detection method in an exchange according to an embodiment of the present invention is applied.

FIG. 2 is an equivalent circuit diagram of a communication path composed of a master unit and a slave unit when a relay contact is switched to a transmission sound generation source side.

FIG. 3 is a communication circuit diagram showing a state in which a plurality of cordless handsets are connected to a parent device to which the on-hook / off-hook detection method in an exchange according to another embodiment of the present invention is applied.

FIG. 4 is an equivalent circuit diagram showing a configuration of an on-hook / off-hook detection method in a conventional exchange that detects an on-hook or off-hook state of an extension terminal.

5 is an electric circuit diagram showing a configuration of a hook detection resistor shown in FIG.

[Explanation of symbols]

 11 Master Unit 12 Slave Unit 14 Circuit Impedance of Slave Unit 19 Circuit Impedance of Master Unit 23 Constant Voltage Diode 25 Comparator Vref Reference Voltage

Claims (1)

[Claims] 1. An extension terminal on-hook or off-hook when the exchange controls each extension terminal according to the on-hook or off-hook state of the extension terminal at the time of connection between extension terminals or connection to an outside line. In the on-hook / off-hook detection method for detecting the state of, the reference set to a voltage level between the terminal voltage of the extension terminal when the extension terminal is in the on-hook state and the terminal voltage when the extension terminal is in the off-hook state. By generating a voltage, detecting the terminal voltage corresponding to the difference in circuit impedance on the extension terminal side when the extension terminal is in the on-hook or off-hook state, and comparing the terminal voltage with the reference voltage. , An on-hook or off-hook state of the extension terminal is detected. On-hook / off-hook detection method in exchange.