KR20010047739A - Apparatus for automatic hold release in 2 line telephone - Google Patents

Abstract

PURPOSE: An automatic hold releasing apparatus of two line telephone is provided to lengthen an immunity time of a line interruption, sensibly perform an automatic releasing detection and be stably operated by solving a contradictional relation existing between an automatic releasing and a line interruption time of hold and allowing more time to adjust a time constant. CONSTITUTION: A hold forming unit(30) checks a voltage variation of an inputted hold signal and maintains a hold. A line interruption preventing unit(40) prevents a line interruption when a voltage variation occurs in the hold forming unit(30). An automatic releasing detector(50) monitors the hold forming unit(30), adjusts an immunity time for the line interruption of the line interruption preventing unit(40) by controlling charging and discharging time of a time constant, and automatically releases the hold of the hold forming unit(30). The automatic releasing detector(50) includes the second condenser(C2) for continuously monitoring the hold state of the hold forming unit(30) and performing an inverse-charging if the voltage variation occurs; the third transistor(Q3) connected to the second condenser(C2) and a base input terminal; and the fourth transistor(Q4) of which a base input terminal is connected to the connection portion between the third transistor(Q3) and the third condenser(C3) and a collector output terminal is connected to the hold forming unit(30).

Description

Apparatus for automatic hold release in 2 line telephones

The present invention relates to an automatic hold release device of a two-line telephone, and in particular, in the configuration of an automatic hold release circuit, it is recognized as an automatic release signal when a line interruption occurs, thereby releasing the hold state so as to be suitable for preventing disconnection of a call. An automatic hold release device for a two-line telephone.

The automatic hold release circuit of the conventional two-line telephone automatically checks the voltage change at the line-end and automatically holds the hold by considering it as reconnecting the call using a telephone branched from the telephone in the holding state when a voltage change occurs. It will be released (Auto Release).

Most line voltage fluctuations are caused by branch phones, but if a line interruption occurs for a short time, voltage fluctuations also occur at the line ends and hold must be maintained at this time. do.

1 is a block diagram of a conventional automatic hold release device of a two-line telephone.

As shown therein, reference numeral 10 denotes a hold forming portion, and 20 denotes a line interruption preventing portion. BD is a bridge diode, R is a resistor, C is a capacitor, and Q is a transistor.

So in the case of a two-line phone, each line can have a hold state, so it is not possible to hold a DC loop in the speech network at the back end.

Each line implements the hold function by forming a DC loop at the front of the line.

The hold itself is constructed by using the latches of two transistors Q1 and Q2 in the hold forming portion 10.

Therefore, when a high signal is applied to the base of the Q9 transistor, Q9 is turned on, and then Q1 is sequentially turned on to hold.

In this state, when the parallel-connected telephone is switched to the call state, voltage change occurs at the line end. The voltage drop (Drop) of the line stage is applied to the base of Q2 through the R1 resistance, which causes the hold to be released as Q2 is turned off.

In this case, when the voltage drop occurs in R4 and C2 in the line interruption prevention unit 20, reverse discharge is performed, and the automatic release is normally operated by adjusting the discharge time, and the immunity of the line interruption is determined. It sets the time to have immunity, but it is difficult to satisfy both condition of automatic release and line interruption.

All adjustable times must meet two conditions after the line is disconnected and before the natural discharge is complete. In other words, if the reverse discharge time is too short, the immunity for the line interruption is strong, but the automatic release is not good. On the contrary, if the reverse discharge time is long, the automatic discharge is fine but the immunity time for the line interruption becomes short.

However, this conventional technique is limited and very difficult to adjust the common time between the automatic release and the line interruption time, so inevitably it is biased towards one of the two requirements of the automatic release and the line interruption. The circuit time is calculated based on the automatic release function, which is a popular function, which has the limitation that the automatic release and line interruption cannot be satisfied at the same time.

Accordingly, the present invention has been proposed to solve the conventional problems as described above, and an object of the present invention is to recognize the automatic release signal when a line interruption occurs in the configuration of the automatic hold release circuit, thereby releasing the hold state, thereby connecting to a call. It is to provide an automatic hold release device of a two-line telephone that can be prevented from breaking.

In order to achieve the above object, the automatic hold release device of a two-line telephone according to the present invention,

A hold forming unit which checks a voltage change of the received hold signal and maintains the hold; A line interruption prevention unit which prevents line interruption when a voltage change occurs in the hold forming unit; An automatic release detection unit monitors the hold forming unit, adjusts the charge and discharge time of the time constant, adjusts the immunity time for the line interruption of the line interruption preventing unit, and automatically releases the hold of the holding forming unit. It is characterized by the technical configuration.

1 is a block diagram of an automatic hold release device of a conventional two-line telephone,

2 is a block diagram of an automatic hold release device for a two-line telephone according to the present invention.

Explanation of symbols on the main parts of the drawings

10, 30: hold forming portion 20, 40: line interruption preventing portion

50: automatic release detector

Hereinafter, an embodiment according to the technical idea of the automatic hold release device of the present invention two-line telephone as follows.

2 is a block diagram of an automatic hold release device for a two-line telephone according to the present invention.

As shown therein, the hold forming unit 30 checks the voltage change of the received hold signal and maintains the hold; A line interruption prevention unit 40 which prevents line interruption when a voltage change occurs in the hold forming unit 30; The hold forming unit 30 is monitored, and the immunity time for the line interruption of the line interruption preventing unit 40 is adjusted by adjusting the charge / discharge time of the time constant, and the hold forming unit 30 It is composed of an automatic release detection unit 50 so that the hold of the automatic release.

The automatic release detector 50 includes: a second capacitor C2 for continuously monitoring the hold state of the hold forming unit 30 and performing reverse discharge when a voltage change occurs; A third transistor Q3 connected to the second capacitor C2 and a base input terminal; A third capacitor C3 connected to the collector output terminal of the third transistor Q3; A base input terminal is connected to a connection portion of the third transistor Q3 and the third capacitor C3, and a collector output terminal includes a fourth transistor Q4 connected to the hold forming unit 30.

In the above, the charging time of the third capacitor (C3) is set faster than the discharge time of the second capacitor (C2).

Referring to the accompanying drawings, the operation of the automatic hold release device of the two-line telephone according to the present invention configured as described above will be described in detail as follows.

First, the present invention basically sets the time existing between the line interruption immunity and the automatic hold release more easily, and also realizes the stable operation of the automatic release upon hold.

Unlike the related art, the automatic release detection unit 50 is additionally added to the latch circuit of the transistor, and a portion for adjusting the RC charge / discharge time is separately provided at the next stage to allow the automatic release to be more stably operated. It is easy to adjust and extend the time for the community. That is, the hold forming unit 30, which is a basic hold loop circuit, is the same as in the related art, and operates the automatic release part and the time constant adjusting part separately to improve the adjustability and stability.

Referring to the operation of the present invention in more detail as follows.

First, the hold signal enters the hold mode while applying a high signal to the base of the Q2 transistor of the hold forming unit 30.

The base high signal of Q2 then turns on Q2, whereby Q1 is turned on to form a latch circuit by Q1 and Q2.

In the DC loop circuit, a main path is formed through Q1. At this time, since it is a two-line telephone, the speech part of the rear end is disconnected.

Then, when the handset of the telephones connected in parallel in the hold mode, a voltage drop occurs at the line end. At this time, R5, R6, R7, C2, and Q3 of the automatic release detector 50 operate.

So Q3 is kept on because it normally receives a high signal through R6. When a voltage drop occurs, C2 starts reverse discharge through R5.

As the base end of Q3 momentarily becomes 0 volts or less, the discharge is maintained by the RC time constant, and is turned off during this time.

As soon as Q3 is turned off, the high of the line stage flows in through R8. First, after charging C3, a high signal is applied to the base of Q4 to turn on Q4, thereby turning Q2 off.

As one transistor Q2 of the hold forming unit 30 is turned off, the other transistor Q1 is also turned off, thereby releasing the latch state, and as a result, the hold state is automatically released.

In addition, the charging time of C3 through R8 should be faster than the discharge time of C2.

During line interruption, the line voltage drops from the time the line connection is released. When the voltage drop progresses below the specified voltage, reverse discharge starts at C2 and R5. Q3 is turned off from the start of the reverse discharge, and from this time, C3 is charged through R8. This charging time is later than the discharge time of C2 so that Q4 does not turn on. So adjust the time so that Q4 does not turn on at least from the release of the line until the reconnection of the line.

Accordingly, it is possible to solve the difficulties caused by adjusting the existing time constant points in one place. In addition, since the automatic release detection portion is separately configured, the automatic release operation can be operated more stably than the conventional circuit. In addition, the time constant time can be adjusted within the automatic release detector. In the next stage, the second time constant part is complementary to each other. As a result, the time constant adjustment is free, accurate, and stable operation compared to the conventional apparatus.

As such, the present invention prevents the disconnection of the call by recognizing the automatic release signal when the line interruption occurs in the configuration of the automatic hold release circuit and releasing the hold state.

Although the preferred embodiment of the present invention has been described above, the present invention may use various changes, modifications, and equivalents. It is clear that the present invention can be applied in the same manner by appropriately modifying the above embodiments. Accordingly, the above description does not limit the scope of the invention as defined by the limitations of the following claims.

As described above, the automatic hold release device of the two-line telephone according to the present invention can solve the contradiction relationship existing between the automatic interruption and the line interruption time of the hold, thereby allowing more stable and time constant adjustment. The immunity time of line interruption can be increased, and the automatic release detection can be operated sensitively and operated stably.

Claims (3)

A hold forming unit which checks a voltage change of the received hold signal and maintains the hold; A line interruption prevention unit which prevents line interruption when a voltage change occurs in the hold forming unit; And an automatic release detector for monitoring the hold forming unit, adjusting the charge and discharge time of the time constant, adjusting the immunity time for the line interruption of the line interruption preventing unit, and automatically holding the hold forming unit. Automatic hold release device of a two-line telephone, characterized in that. The method of claim 1, wherein the automatic release detection unit, A second capacitor for continuously monitoring the hold state of the hold forming unit and performing reverse discharge when a voltage change occurs; A third transistor connected to the second capacitor and a base input terminal; A third capacitor connected to the collector output terminal of the third transistor; And a base input terminal is connected to a connection portion of the third transistor and the third capacitor, and a collector output terminal is configured of a fourth transistor connected to the hold forming unit. 3. The apparatus of claim 2, wherein the charging time of the third capacitor is set earlier than the discharge time of the second capacitor.