JPH04371059A - Line state detecting device for communication equipment - Google Patents

Abstract

PURPOSE:To detect a line current, the polarity, and ringing with a simple circuit constitution by operating a device independently of the polarity of a line. CONSTITUTION:This line state detecting device is provided with a charge storage means 3, which charges the electric charge in the case of communication lines L1 and L2 in the idle state and discharges the charged electric charge at the time of polarity inversion of communication lines L1 and L2, and a battery detecting means consisting of a first current detecting part 7 or 8 and a second current detecting part 8 or 7 which are operated by the discharging current of the electric charge stored in the electric charge storage means 3 and are operated in accordance with the line state. The first current detecting part 7 or 8 and the second current detecting part 8 or 7 are operated by currents opposite to each other, and detection signals LS0 and LS1 are outputted in accordance with their operations to detect the line state.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line state detection device, and more particularly to a line state detection device applied to a line interface section in communication equipment such as a modem, facsimile, or private branch exchange having a network control device.

0002

2. Description of the Related Art For example, in a network control device that is housed in a central office exchange and has an automatic call origination/reception function, the timing of an incoming call from the exchange and an outgoing call from a terminal side may coincide, causing a communication collision. It is equipped with a collision prevention function to prevent this. When preventing collisions between incoming and outgoing calls, as is well known, the network control equipment checks the line on the exchange side when receiving calls.
It takes advantage of the fact that the polarity of is reversed. In other words, in the idle state, the lines L1 and L2 of the telephone exchange are L1 = earth (0V) and L2 = battery (-48V), but when a call is received, the polarity is reversed before sending a ringing signal, and L1 = battery, L2 = battery. = become earthly. The network control device detects the battery of the line L1 by utilizing such a change in line polarity, and processes incoming calls with priority.

FIG. 3 shows a conventional technology of a line interface section in such a network control device. As shown in the figure, conventionally, a battery detection circuit 16 such as a relay for monitoring the line L1 or a photocoupler is connected to the line L1 on the terminal side. When the line polarity on the exchange side is reversed, the battery detection circuit 16 detects the battery of the line L1 (-48V
) is being detected. That is, on the terminal side, the signal SEZ is turned ON due to the current flowing through the battery detection circuit 16.
When this occurs, the exchange determines that it has started operations for receiving calls, and stops the originating operations within its own device to prevent collisions between incoming and outgoing calls. The incoming call (ringing) after battery detection is detected by the ringing polarity detection circuit 15, and when the terminal side confirms the incoming call, the relays 12 and 13 close the communication path. At the same time, the battery detection circuit 16 is also disconnected. Thereafter, the polarities of lines L1 and L2 are reversed again, and each relay also returns to the state shown in FIG.

0004

[Problems to be Solved by the Invention] However, in such conventional technology, when connecting the line, if the polarity is incorrect and the battery detection circuit 16 connected to line L1 is connected to line L2, the terminal side will operate as incoming call detection. Therefore, there was a problem in that the outgoing call process could not be performed. There is also the problem that the circuit configuration becomes redundant, as it requires a battery detection circuit 16 that detects line current and polarity during a call, and a ringing polarity detection circuit 15 that detects incoming calls (ringing). Ta.

The present invention eliminates the drawbacks of the prior art and provides a line status detection device for communication equipment that operates regardless of line polarity and can detect line current, polarity, and ringing with a simple circuit configuration. The purpose is to provide.

[0006]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a line state detection device in a communication device that is connected to a communication line and detects the state of the communication line, when the communication line is in an idle state. A charge accumulating means which charges electric charge and discharges the charged electric charge when the communication line performs polarity reversal; and a first electric charge accumulating means which operates based on the discharging current of the electric charge accumulated in the charge accumulating means and which operates according to the state of the line. The battery detection means includes a current detection section and a second current detection section. The line status is notified by outputting .

[0007]

[Operation] According to the present invention, the charge stored in the charge storage means when a call is received is discharged by reversing the polarity of the communication line, and the current flowing at this time is detected by the first current detection section or the second current detection section. do. As a result, it is detected that the line that was connected to the earth is connected to the battery, and the ringing signal sent through the communication line is detected by the first current detection unit and the second current detection unit. do.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a line state detection device for communication equipment according to the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, there is shown a block diagram illustrating an embodiment of a line state detection apparatus according to the present invention. The line state detection device in this embodiment is applied to a line interface section of communication equipment such as a modem, facsimile, or trunk of a private branch exchange having a network control device, and is a device for detecting the state of a connected line. The line state detection device is connected to, for example, a central telephone exchange via lines L1 and L2, and is connected to the main body of the communication device via a transmitting amplifier 1A and a receiving amplifier 1B. As shown in the figure, the line state detection device in this embodiment connects a capacitor 3 for DC isolation, which was conventionally located before the hybrid transformer 2 (on the line side), to a line closing relay 6. A battery detection circuit 9 is provided closer to the line than the capacitor 3, and also detects the station battery, incoming call (ringing), and line polarity reversal.

The battery detection circuit 9 can be connected to either line L1 or L2, and is composed of photocouplers 7 and 8 that detect currents in different directions. When the photocoupler 7 detects a current, it outputs a signal LS1, and when the photocoupler 8 detects a current, it outputs a signal LS0 to a processor (not shown), thereby notifying the processor of a change in the line state. The relay 5 is a relay that is connected to the line L2 when the battery detection circuit 9 is connected to the line L1, and to the line L1 when the battery detection circuit 9 is connected to the line L2, and operates when the communication path is closed. . The DC holding circuit 4 is connected between the lines L1 and L2 on the device side from the relay 5 and the battery detection circuit 9, and is a circuit that holds the DC current so that the line is not released during communication. Capacitor 3 is a capacitor that sends the AC component on the line to hybrid transformer 2 via relay 6. The hybrid transformer 2 is a circuit that couples a two-wire line and a four-wire line, and amplifiers 1A and 1B are connected to the device side of the hybrid transformer 2. Amplifiers 1A and 1B are circuits that amplify communication signals, respectively.

Next, the battery detection circuit 9 of the line state detection device
The operation when is connected to line L1 will be explained. Since the telephone exchange connects the line L1 to the earth (0V) and the line L2 to the battery (-48V) when idle, the capacitor 3 of the line state detection device is charged with electric charge. Also,
When a call is received, the line polarity on the exchange side is reversed, and L1 = battery,
When L2=earth, the electric charge stored in the capacitor 3 is discharged, and a current flows through the photocoupler 8, causing it to operate. Therefore, the signal LS0 is the processor (
(not shown) and the processor detects that line L1 is connected to the battery. After that, the ringing signal similarly operates the photocouplers 7 and 8, so that the signals LS0 and LS1 repeat ON/OFF, so that the processor can detect the incoming call. The processor is
When recognizing that there is an incoming call, relays 5 and 6 are activated to close the communication path. FIG. 2 shows a time chart showing a series of operations related to such a call receiving operation. That is, as shown in the figure, in this embodiment, the processor (not shown) performs LS0+ in a 125 μs scan.
LS1 is monitored, and if this signal indicates an incoming call, the process moves to incoming call (ringing) detection processing. After the station battery is detected, the time it takes to start detecting an incoming call and the monitoring time between ringings is usually a maximum of 2 seconds. Furthermore, in the case of a call from the own device, the line state detection device of this embodiment can also perform reverse detection when the other party is disconnected during a call.

As shown in parentheses in FIG.
, L2 are reversely connected, the charge charged in the capacitor 3 is similarly discharged by reversing the polarity, and the photocoupler 7 operates. Therefore, even in this case, since the signal LS1 is output to the processor, the processor can detect that the line L1 is connected to the battery as described above. Incoming calls (ringing) and line reversal can also be detected in the same way. As described above, according to this embodiment, even if the line is reversely connected, the line state can be detected without malfunction. In this embodiment, the battery detection circuit is constructed of a photocoupler, but this is not particularly limited to a photocoupler, and may be a relay operated by the discharge current of the capacitor 3, for example.

[0013]

[Effects of the Invention] By applying the present invention to a line interface section of a telecommunications line terminal device, etc., which has an automatic call receiving/receiving function, it is possible to connect to a line regardless of the polarity of the line while maintaining the original call receiving function. It is also possible to simplify the hardware that detects the line status associated with automatic call origination and reception. Therefore, even if the line is reversely connected, there will be no erroneous detection as in the prior art, so it is possible to provide a line state detection device that is easy to install, highly reliable, and has high cost performance.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a line state detection device in a communication device according to the present invention;

FIG. 2 is a signal diagram showing the relationship between the discharge current at the time of incoming call and LS0 and LS1 in the embodiment shown in FIG.

FIG. 3 is a block diagram of a line interface section of a telephone terminal in the prior art.

[Explanation of symbols]

3 Capacitor 4 DC holding circuit 5,6 Relay 7, 8 Photocoupler 9 Battery detection circuit

Claims (1)

[Claims] Claim 1. A line state detection device in a communication device connected to a communication line and detecting the state of the communication line, the device charging an electric charge when the communication line is in an idle state, and detecting the polarity of the communication line. A charge storage means that discharges the charged charge when inversion is performed, and a first current detection section and a second current detection section that operate based on the discharge current of the charge accumulated in the charge storage means and that operate according to the line state. The first current detecting section and the second current detecting section are operated by currents in different directions, and the line is detected by outputting a detection signal in accordance with the operation. A line state detection device for a communication device characterized by notifying the state.