JPH041541B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a telephone having an automatic hold release function.

(b) Conventional technology The automatic hold release function of a telephone set has two
When two telephones are connected in parallel in a so-called branch connection, when one telephone places the telephone on hold and the other telephone goes off-hook, the telephone that was on hold first is automatically released from hold. This is an on-hook state. This function is very convenient for the user because it allows the user to hang up the call without having to go through the trouble of picking up the phone that placed the call on hold. The traditional method for implementing this feature is to place the hold on hold by detecting the line voltage fluctuations caused by the current flowing into the branching phone when it goes off-hook. It was automatically released and left in an on-hook state.

On the other hand, one of the services that Nippon Dentsu Telephone Corporation (NTT) is currently providing to general users is a telephone called Pink Denwa that allows the user to collect and manage telephone call charges. There is. The charge collection method for this pink telephone is carried out by receiving signal sending services such as coin collection from the telephone office at the same time as the installation. In this service, when the other party answers and during a call, a signal for periodically storing coins (hereinafter referred to as a storing signal) called a billing pulse is sent depending on the region of the other party, such as reversing the polarity of the line, It is sent out in the form of depolarization. This signal sending service for coin storage, etc. is also provided for individual telephone contract lines, and if the signal sent by receiving only this service is detected, it is possible to calculate the charge, and recently such services have become available. Telephones that can calculate charges are also appearing.

(c) Problems to be solved by the invention In telephones receiving such signal sending services such as coin storage, or in telephones used in branch connection with pink telephones, the conventional automatic hold release method is However, there was a drawback in that if a withdrawal signal was received while the system was on hold, the reception signal would malfunction and cause the line to go off-hook. The cause of malfunction is when the polarity of the line in the periodic storage signal is reversed as shown in Figure 4.
The cause of this is the open state that is maintained for a certain period of time (t ₂ ) as the relay switching timing on the station side during each process of the depolarization operation, which returns to the original state after reversal. The time _t1 of the signal width as a pulse and whether the open state occurs at inversion or depolarization differ depending on the exchange at the office, but an open state can occur in any exchange. so time t ₂
is not defined in the technical standards. According to actual measurements, t ₂ is approximately 0.1 seconds, and power is not supplied to the terminal phone during this time, and it is difficult to distinguish between this state and line voltage fluctuations due to off-hook of the branch phone to cancel automatic hold. Since this is not possible, a pending storage signal may cause a malfunction. Therefore, in the conventional automatic hold release device, when connected to a line receiving a signal sending service such as coin storage, the automatic hold release function was not utilized.

The present invention is intended to solve the above-mentioned problem, that is, the malfunction that occurs due to the collection signal when a telephone with an automatic hold release function is connected to a line that receives a signal transmission service such as coin storage.

(d) Means for Solving the Problems The present invention provides voltage comparison means for comparing the voltage drop value caused by the charge collection signal sent from the line when a call is on hold with a predetermined value set in advance; The present invention includes a time comparison means for comparing the time with a predetermined time set in advance, and compares the voltage drop caused by the toll collection signal and the voltage drop caused by the on-hook by the voltage comparison means and the time comparison means to distinguish between the two.

(e) Effect The voltage drop caused by the toll collection signal is short-lived;
Since the voltage drop due to off-hook takes a long time compared to this, the two can be distinguished by comparing not only the voltage comparison means but also the time comparison means, and no on-hook occurs due to the toll collection signal.

(f) Examples The present invention will be explained below with reference to FIGS. 1 to 3. FIG. 1 is a time chart for explaining the operation of one embodiment of the present invention, FIG. 2 is a circuit block diagram, and FIG.
The figure is also a flowchart for explaining the operation.

FIG. 2 is a circuit block diagram of an automatic hold release device according to an embodiment of the present invention. 1 is a first telephone having an automatic hold release function; 2 is a second telephone branch-connected to the first telephone 1; 3 is a rosette; 4 is a bridge diode; 5 is a hook state control unit; speech network IC,
7 is a switch, 8 is an AD converter, 9 is a battery, 10 is a control processing unit (CPU), 11,
12 is a control bus, and 13 is a hold button.

First, after making a call from the first telephone 1 having the automatic hold release device of the present invention, the call is put on hold (by pressing the hold button 13 in FIG. 2). After this, CPU10
An AD conversion start signal is sent to the AD converter 8 via the control bus 12 to digitize the voltage input (Ain) obtained by rectifying the line voltage. This digitized data is input to the CPU 10 from the bus 12 and is stored as a reference voltage (V _REF ). This reference voltage (V _REF ) takes into account the drop caused by pressing the hold button during the open state time (T ₁ ) of the storage signal (caused by the drop in impedance due to the connection of two devices), and from then on, the reference voltage (V REF ) will be higher than V _REF . If voltage data is input, a new V _REF setting is performed. Furthermore, after determining V _REF , Ain is constantly monitored while AD conversion continues.

There are two elements necessary to distinguish between a drop-off signal and a branch telephone off-hook.
One is the voltage drop V ₁ in the open state of the storage signal
(0.1 to 1.0V) and the voltage drop V ₂ (approximately 1.0V) due to off-hook of the branch telephone, and the other is the open state time T ₁ (approximately 0.1V) of the storage signal.
seconds) and the elapsed time (>T ₁ ) after the branch phone went off-hook.

If only the former is used for identification, if a telephone with a large DC resistance is connected to a branch, V ₁
<V ₂ , so the element of time difference is required. Therefore, in the CPU 10, a comparison voltage (V _CM ) (0.7V) of the voltage fluctuation obtained by removing fluctuation factors such as audio level from the voltage drop caused by the branch is set in advance.
Set the time T ₂ that has elapsed in a voltage drop state where the difference between V _REF and Ain exceeds V _CM . Comparison voltage V _CM
is determined uniquely from within the DC resistance range that allows branch connection, and T ₂ is also sufficiently larger than the actual measured value of the stored signal (for example, T ₂ ≧5t ₂ ), and can be determined uniquely considering practicality. It is.

In the program, after holding and determining V _REF , Ain
and V _REF (V _REF ≧Ain), and when the value exceeds V _CM and _T2 has elapsed, the CPU 10 sends an on-hook signal to the control bus 11, Controls the hook state control section 5. As a result, the hold of the first telephone 1 is automatically released and the first telephone 1 enters an on-hook state. If a branched phone is taken off-hook:
This is the function of the CPU10.

In addition, in the case of a storage signal, V ₁ in its open state is one of the conditions for automatic hold release, V ₁
Even if =V _REF −Ain>V _CM is satisfied, the other condition T ₁ ≧T ₂ is not satisfied, so automatic suspension release is not executed. As a result, the call is automatically released from hold when the branch telephone is off-hook, but the call is not automatically released from hold when the phone is picked up, so malfunctions can be prevented. Note that in the open state of the storage signal, as shown in FIG. 1, the waveform does not become OV due to the line capacitance of the line, and therefore the voltage value after rectification does not fall to the OV level.

(g) Effects of the Invention As explained above, according to the present invention, even if a telephone with an automatic hold release function is connected to a line receiving signal sending services such as coin storage, malfunctions will not occur due to the storage signal. Therefore, the automatic hold release function can be fully utilized.

[Brief explanation of drawings]

FIG. 1 is a time chart for explaining the operation of an embodiment of the present invention, FIG. 2 is a circuit block diagram, FIG. 3 is a flow chart for explaining the operation, and FIG.
The figure shows a storage signal. 1...First telephone, 2...Second telephone, 5
...Hook state control unit, 7...Hook switch, 8...AD converter, 10...Control processing unit (CPU), 13...Hold button.

Claims (1)

[Claims] 1. In an automatic hold release device in which a second phone is connected in parallel to a first phone having an automatic hold release function, the voltage drop value due to a charge collection signal sent from a line when a call is on hold is determined in advance. A voltage comparison means for comparing with a preset predetermined value, and a time comparison means for comparing the voltage drop time due to the charge collection signal with a preset predetermined time, the charge sent when the first telephone is on hold. An automatic hold release device characterized in that the voltage drop due to the storage signal and the voltage drop due to the off-hook of the second telephone are compared by the voltage comparison means and the time comparison means to discriminate between the two.