JPH0157861B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a public telephone in which failures in the public telephone can be monitored on the exchange side. When some kind of failure occurs in a public telephone (for example, the safe in the public telephone becomes full), it is necessary for the switching center to automatically detect the occurrence of the failure in the public telephone. An object of the present invention is to provide a public telephone that automatically sends a signal indicating whether or not a failure has occurred in the public telephone to the exchange without modifying the exchange itself within the exchange. There is. In order to achieve this purpose, the public telephone of the present invention has a hook switch HS1,
a communication circuit 21 connected to line terminals B1 and B2 via HS2 and supplied with a line current having a value greater than the minimum line current for starting the switch;
A battery 23 connected to line terminals B1 and B2 via HS2 and charged by a line current having a value smaller than the switch recovery minimum line current.
And, when the handset is raised, switch HS3 is activated.
a control circuit 25 that is connected to the battery 23 through a power supply and is supplied with power from the battery 23, and outputs a fault signal when the handset is lifted up if a fault occurs inside the public telephone; a fault detection means operated by a signal; and a fault detection means inserted between the battery 23 and the switch, the battery 23 being connected to the switch.
When connected to line terminals B1 and B2 via HS1 and HS2, when the fault detection means is inactive, the charging current of the battery 23 is limited to a value smaller than the exchange recovery minimum line current, and the fault detection means In the operating state of the detection means, the detection means includes a current control circuit 32 that releases the restriction on the charging current of the battery 23 and switches to supply a current having an intermediate value between the exchange recovery minimum line current and the exchange start-up minimum line current. It is characterized by Embodiments of the present invention will be described below based on the drawings. FIG. 1 shows an embodiment of the invention. In Figure 1, 1 is an exchange, and 11 is an exchange 1.
2 is a public telephone of the present invention, L1, L2
is a line connecting exchange 1 and public telephone 2,
A1 and A2 are line terminals of exchange 1, B1 and B2
is the line terminal of the public telephone 2. 21 is a communication circuit, 22 is a rectifier bridge, 23 is a rechargeable battery, 25 is a control circuit for controlling coin storage and other operations of the public telephone 2;
P1 and P2 are power supply terminals that connect the control circuit 25 to the battery 23. HS1, HS2, and HS3 are switch switches. When the public telephone 2 is in use, the switch switches HS1 to HS3 are switched from the positions shown in Figure 1, and the telephone circuit 21 is connected to the lines L1 and L2, and the battery 23 is line L1, L2
It is disconnected from the control circuit 25 and connected to the control circuit 25. When the public telephone 2 is not in use, the switch switches HS1 to HS3 are in the position shown in FIG. It will be charged. Reference numeral 31 denotes a failure detection circuit for detecting some kind of failure in the public telephone 2 (for example, the safe is full) immediately after the handset is picked up, based on a signal from the control circuit 25. Reference numeral 33 denotes a fault detection relay that operates when the fault detection circuit 31 detects a fault and returns to normal operation when the fault is cleared. 32, when the line current charging the battery 23 when the public telephone 2 is not in use is a current that is smaller than the minimum line current for recovery of the exchange if the fault detection circuit 31 does not detect a fault; When a fault is detected, the current control circuit controls the current value to an intermediate value between the switch recovery minimum line current and the switch startup minimum line current, and is closed by the operation of the fault detection relay 33. The relay contact 34 and the relay contact 3
4 is open, the charging current to the battery 23 is limited to a current smaller than the exchanger recovery minimum line current, and when the relay contact 34 is closed, it is short-circuited and the charging current is reduced to the exchanger recovery minimum line current and exchanger startup. A current limiting circuit 24 sets the line current to a value intermediate between the minimum line current and the minimum line current. As shown in FIG. 2, this detection relay 33 detects the public telephone by the output of the fault detection circuit 31 immediately after the formation of the DC loop after a certain period of time t1 after the handset is raised. It operates when a failure of 2 occurs (Fig. 2c). After the telephone has been used, it will temporarily recover at t3 when the next new handset is raised, and if the fault has not been cleared, it will resume operation immediately after t4 when a DC loop is formed, as shown in Figure 2c. do. If the fault has been removed, the system remains restored as shown in FIG. 2d. As shown in FIG. 1, the switching center 1 side has a system for monitoring faults on the public telephone 2 side based on changes in the charging current to the battery 23 due to detection and non-detection of the fault on the public telephone 2 side. A fault signal monitoring circuit 4 is provided. Fault signal monitoring circuit 4
are inserted in series between the exchange 11 and the line terminals A1 and A2. As shown in FIG. 3, this fault signal monitoring circuit 4 includes first and second current level detection circuits 41 and 42 that detect the magnitude of line current, and detects the line current from the outputs of these circuits 41 and 42. It includes a determination circuit 43 that determines the level, a storage circuit 44 that stores the output of the determination circuit 43, and a display circuit 45. Note that RB is a reset button for the memory circuit 44. The detection level of the first current level detection circuit 41 is set to an appropriate value (for example, 6 mA) that is slightly larger than the minimum recovery line current of the exchange 11. Further, the detection level of the second current level detection circuit 42 is set to an appropriate value (for example, 14 mA) that is slightly smaller than the minimum starting line current of the exchange 11. Next, the operation of this embodiment will be explained. Here, the minimum starting current value of the exchange 11 is approximately 18 m
A. The maximum value of the line current when the phone is not in use is approximately 3 mA (taking into consideration the battery charging current and leakage current between lines L1 and L2). Said first
For example, the detection level of the current level detection circuit 41 is set to 6 mA, the detection level of the second current level detection circuit 42 is set to 14 mA, and the current is adjusted so that the line current when the relay contact 34 closes due to failure detection is approximately 9 mA. A case where constants of the limiting circuit 24 are set will be explained. Further, it is assumed that the failure detection circuit 31 detects, for example, when the safe is full. (b) When you raise the handset, the switch HS1,
The communication circuit is connected to the lines L1 and L by HS2, and the switch 11 → the first current level detection circuit 41
→Line L1→Hook switch HS1→Talking circuit 21→Hook switch HS2→Line L2→
A minimum line current of about 18 mA flows in the loop from the second current level detection circuit to the exchange 11. This line current is at the detection level of the first and second current level detection circuits 41 and 42 (14
mA, 6mA), the judgment circuit 4
3, it is determined that the telephone is in use. (b) Immediately after lifting the handset, the fault detection circuit 31 checks whether the safe is full. If it is not full, the detection relay 33 does not operate. Therefore, relay contact 34 is open. When the call ends in this state and the handset is hung up, the switchboard switches HS1 to HS3 move to the positions shown in FIG.
→ Line L1 → Hook switch HS1 → Rectifier bridge 22 → Current limiting circuit 24 → Battery 2
3 → Rectifier bridge 22 → Hook switch HS2
The battery 23 is charged in the loop of → line L2 → second current level detection circuit → exchange 11. The total value of this battery charging current and leakage current, approximately 3 mA, corresponds to the detection levels of the first and second current level detection circuits 41 and 42 (14 mA and 6 mA, respectively).
mA), the determination circuit 43 determines that the telephone is not in use and there is no failure. (c) If the safe is full, a fault signal is output from the fault detection circuit 31 immediately after the handset is raised, the detection relay 33 is activated, and the relay contact 34 is closed. When the call ends in this state and the handset is hung up, a line current of 9 mA flows in the same loop as in the previous section (b). Since this current level is higher than the detection level (6 mA) of the first current level detection circuit 41 and lower than the detection level (14 mA) of the second current level detection circuit 42, the determination circuit 43 indicates that a failure has occurred in the public telephone 2. It is determined that the The judgment result of this judgment circuit 43 is stored in a storage circuit 44.
is memorized, and the display circuit 45 lights up a lamp or sounds a buzzer. By pressing the reset button RB after the safe is released from full, the memory in the memory circuit 44 is cleared. As described above, the fault signal monitoring circuit 4 constantly monitors the magnitude of the line current, and the occurrence of a fault in the public telephone 2 is detected by the fault signal monitoring circuit 4 based on the magnitude of the line current. It is also detected whether the public telephone 2 is in use. In addition, when a fault in the public telephone 2 is detected in this way, at the same time as the time t5 (see Figure 2) when the handset of the public telephone 2 is hung up,
Since the line current of A continues to flow, switch 1
1 continues to be activated without being restored. Therefore,
If the switchboard remains activated, it will not be possible to make another call, but as shown in Figure 2c, the handset is raised to use public telephone 2 next (t ₃
After the point in time), it takes a certain amount of time until a DC loop is formed between the communication circuit 21 and the lines L1 and L2.
During this time, the control circuit 25 controls the fault detection circuit 31 to restore the detection relay 33 even if the fault has not been cleared, so that the line current becomes approximately 3 mA as in the case of the previous section (b). Therefore, at this time, the exchange 11 is restored and the next call becomes possible. The reason why we made it possible to make the next call even if a failure was detected in this way was because it was possible to use a public telephone a little longer without any problem, such as when the safe was full. In the case of a serious failure, such temporary restoration of the failure detection relay 33 can be stopped to prevent the next call from being made. In the above embodiment, a case has been described in which the fault detection circuit 31 detects a full state of the safe, but it can also detect various faults such as removing the safe, opening the door of the public telephone, removing the main body of the public telephone, etc. You can also do this. As explained above, since the public telephone of the present invention is configured, the battery 23 is charged with line current when the telephone is not in use, and is used as a power source for the control circuit inside the public telephone. By controlling the charging current of 23 to take a different value depending on whether or not a fault has occurred, it becomes possible to automatically notify the switching office of the presence or absence of a fault in the public telephone.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is a timing chart showing its operation, and Fig. 3 is a diagram showing an embodiment of the present invention.
FIG. 1 is a block diagram showing the configuration of the fault signal monitoring circuit in FIG. 1. 1... Switching station, 11... Switching machine, L1, L2...
... Line, 2 ... Public telephone, 21 ... Call circuit, 22 ... Rectifier bridge, 23 ... Battery, 24 ... Current limiting circuit, 25 ... Control circuit,
HS1, HS2, HS3...Full switch, 31
...Fault detection circuit, 32...Current control circuit, 33
...Fault detection relay, 34...Relay contact, 4...
...fault signal monitoring circuit, 41...first current level detection circuit, 42...second current level detection circuit,
43... Judgment circuit, 44... Memory circuit, 45...
Display circuit, RB...reset button.

Claims (1)

[Scope of Claims] 1. In the call loop formation state, a current with a value larger than the switch activation minimum line current is supplied from the exchange side, and in the call loop disconnection state, a current with a value smaller than the exchange recovery minimum line current is supplied from the exchange side. In public telephones that receive electric current, when the handset is raised, the switch HS1,
a communication circuit 21 connected to line terminals B1 and B2 via HS2 and supplied with a line current having a value greater than the minimum line current for starting the switch;
A battery 23 connected to line terminals B1 and B2 via HS2 and charged by a line current having a value smaller than the switch recovery minimum line current.
And, when the handset is raised, switch HS3 is activated.
a control circuit 25 that is connected to the battery 23 through a power supply and is supplied with power from the battery 23, and outputs a fault signal when the handset is lifted up if a fault occurs inside the public telephone; a fault detection means operated by a signal; and a fault detection means inserted between the battery 23 and the switch, the battery 23 being connected to the switch.
When connected to line terminals B1 and B2 via HS1 and HS2, when the fault detection means is inactive, the charging current of the battery 23 is limited to a value smaller than the exchange recovery minimum line current, and the fault detection means In the operating state of the detection means, the detection means includes a current control circuit 32 that releases the restriction on the charging current of the battery 23 and switches to supply a current having an intermediate value between the exchange recovery minimum line current and the exchange start-up minimum line current. A public telephone that is characterized by: