JPH04249995A - Telephone set circuit for wired broadcast telephone set - Google Patents

Abstract

PURPOSE:To eliminate a permanent call state electrically and to use the line for talking regardless of the permanent call state takes place in the line. CONSTITUTION:A 32Hz signal detection circuit 11 receives a 32Hz signal outputted from an exchange 3 and outputs a signal of logical '1', and a 16Hz signal detection circuit 4 receives a 16Hz signal outputted from the exchange 3 and outputs a signal of logical '1' respectively. A loop detection circuit 6 outputs a signal of logic 1 when a loop is formed by lines 11, 12 from the exchange and a telephone set. An OR circuit 5 outputs an OR signal between a signal from the 32Hz detection circuit 11 and a signal from the 16Hz detection circuit 4. An AND circuit 7 outputs an AND between a signal outputted from the OR circuit and a signal outputted from the loop detection circuit. A relay 8 is active by the output of the AND circuit, a resistor is connected in the loop by a contact to increase the impedance in the loop so as to disconnect the telephone set apparently.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a telephone circuit for a wired broadcast telephone, and more particularly to a telephone circuit for a wire broadcast telephone that controls disconnection of the handset/receiver circuit of a plurality of telephones connected on the same line in a wire broadcast telephone system. Regarding.

0002

2. Description of the Related Art Conventionally, in a wired broadcast telephone system, a plurality of telephones are connected to the same line, and calls to other telephones on the same line are made using a 16Hz signal sent from an exchange. This is done by calling. If even one telephone is disconnected from its handset on the same line, the communication function with the telephone on that line has to be stopped.

0003

[Problem to be Solved by the Invention] In the above-mentioned conventional cable broadcasting telephone system, when a subscriber notices that there is a telephone on the same line whose handset is disconnected due to forgetting to dial the receiver, etc. Until the condition of disconnecting the handset is resolved,
This has the disadvantage that the line becomes unusable for a long period of time.

[0004] Furthermore, when a subscriber calls another subscriber on the same line, the 16Hz signal sent from the exchange is transmitted not only to the telephone of the other subscriber but also to the caller's own telephone. This has the disadvantage that the capacity of the 16Hz oscillation circuit of the exchange must be increased.

[0005] An object of the present invention is to make it possible to eliminate the handset-removed condition and use the line for telephone calls under control from the exchange, and to ensure that the 16Hz signal sent from the exchange is To provide a telephone circuit for a wired broadcast telephone that can prevent a call from being broadcast to a caller's own telephone.

[0006]

[Means for Solving the Problems] A telephone circuit for a wired broadcast telephone according to the present invention comprises (A) a 32Hz signal detection circuit that receives a 32Hz signal output from an exchange and outputs a signal with a logical value of "1"; ) A 16Hz signal detection circuit that receives a 16Hz signal output from the exchange and outputs a signal with a logic value of "1"; (C) a 16Hz signal detection circuit that receives a 16Hz signal output from the exchange and outputs a signal with a logic value of "1"; (D) an OR circuit that outputs the logical sum of the signal output from the 32Hz signal detection circuit and the signal output from the 16Hz signal detection circuit; (E)
(F) an AND circuit that outputs the logical product of the signal output from the OR circuit and the signal output from the loop detection circuit; (F) operated by the output of the AND circuit; Inside the configured loop,
It is equipped with a relay that connects a resistor through contacts to increase the impedance in the loop.

[0007]

Embodiments Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a telephone circuit for wired broadcasting telephones according to the present invention.

The telephone circuit for wired broadcasting telephone of this embodiment is as follows:
As shown in FIG. 1, a 32Hz signal detection circuit 11 receives a 32Hz signal output from the exchange 3 and outputs a signal with a logic value "1", and a 32Hz signal detection circuit 11 receives a 16Hz signal output from the exchange 3 and outputs a signal with a logic value "1". 16Hz signal detection circuit 4 that outputs a signal of 16Hz, a loop detection circuit 6 that outputs a signal with a logic value of "1" when a loop is formed by the lines 11 and 12 from the exchange 3 and the telephone 2, and a 32Hz signal detection circuit 11 and the signal output from the 16Hz signal detection circuit 4; The AND circuit 7 outputs the logical product, and the lines 11 and 1 from the exchange 3 are operated by the output of the AND circuit 7.
2 and the telephone 2, a relay 8 is connected to a resistor 10 through a contact 9 to increase the impedance in the loop.

Next, the operation will be explained.

FIG. 2 is a diagram showing the timing of the operation of the cable broadcast telephone circuit of FIG. 1. In FIG.

In FIG. 1, when there is a telephone on the lines 12 and 13 whose handset is disconnected due to forgetting to dial it, etc., the exchange 3 measures the time it remains in that state and waits for a predetermined period of time to elapse. At that time, 32Hz from exchange 3
When a signal of 32 Hz is sent to the telephone set in the disconnected state and this 32 Hz signal is detected by the 32 Hz signal detection circuit 11, the 32 Hz signal detection circuit 11 outputs a logic value of "1".
” signal is output, and the output of the OR circuit 15 is the logical value “1”.
". On the other hand, since the handset is disconnected, this state is detected by the loop detection circuit 6, and the loop detection circuit 6 outputs a signal with a logical value of "1". When receiving a 32Hz signal from
The output of the AND circuit 7 becomes "1", and the relay 8 is activated by this output. Contact 9 of this relay causes telephone 2 to
A resistor 10 is connected in series with . For this reason, the telephone set 2 appears to be in a disconnected state as shown in FIG.
, 13 can now be used for telephone calls. Note that the value of the resistor 10 is the maximum value within the range in which the loop detection circuit 6 operates.

The state in which the telephone is apparently disconnected due to high impedance is maintained until the handset is returned to normal. When the telephone is returned to normal, the loop detection circuit 6 is turned off, and the output of the loop detection circuit 6 causes 32Hz
The output from the signal detection circuit 11 has a logical value of "0" and returns to the initial state.

Next, when a subscriber calls another subscriber on the same line, a 16 Hz signal is output from the exchange 3. At this time, the 16Hz signal detection circuit 4 detects the OR
The output of the circuit 5 has a logical value of "1".

On the other hand, since the loop detection circuit 6 outputs a signal with a logical value of "1", when a 32 Hz signal is received from the exchange 3, the output of the AND circuit 7 becomes "1".
This output activates the relay 8. A resistor 10 is connected in series to the telephone 2 through the contact 9 of this relay. Therefore, the telephone appears to be in a disconnected state as shown in FIG. 2 due to high impedance, and it becomes possible to call another telephone.

In this state, when there is an incoming call response from the called party, the exchange 3 stops the 16Hz signal, so the output of the 16Hz signal detection circuit 4 is turned off, and the OR circuit 5 and the AND circuit The output of 7 becomes "0". Then, since the output of the AND circuit 7 becomes "0", the relay 8 is restored, and due to the restoration of the relay 8, the telephone 2
Since the resistor 10 connected in series with the telephone 2 is removed, the telephone 2 can now be used for telephone calls.

[0017]

[Effects of the Invention] As explained above, the telephone circuit for wired broadcasting telephones of the present invention receives the 32Hz signal sent from the exchange when the handset is disconnected, and controls the impedance of the telephone by the relay. This has the effect that even if the handset is actually disconnected, the disconnected condition can be electrically canceled and the line can be used for telephone calls.

[0018] Furthermore, when a subscriber lifts the handset to call another subscriber on the same line, the handset is disconnected, so the 32Hz signal sent from the exchange is received and the relay is activated. The impedance of the telephone is controlled, and the 16Hz signal flowing from the exchange can be prevented from flowing to the caller's own telephone, which has the effect of not increasing the capacity of the 16Hz oscillation circuit of the exchange. ing.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a telephone circuit for a wired broadcast telephone according to the present invention.

FIG. 2 is a diagram showing the timing of the operation of the wired broadcast telephone telephone circuit of FIG. 1;

[Explanation of symbols]

2　　　　Telephone 3　　　　　Exchange machine 4 16Hz signal detection circuit 5 OR circuit 6 Loop detection circuit 7 AND circuit 8 Relay 9 Contact 10 Resistor 11 32Hz signal detection circuit 12,13 line

Claims (1)

[Claims] 1. (A) A 32Hz signal detection circuit that receives a 32Hz signal output from the exchange and outputs a signal with a logical value of "1," (B) A 32Hz signal detection circuit that receives a 16Hz signal output from the exchange and outputs a signal with a logical value of "1." (C) a loop detection circuit that outputs a signal with a logical value of "1" when a loop is formed by the line from the exchange and the telephone; (D) the 32Hz signal; an OR circuit that outputs the logical sum of the signal output from the signal detection circuit and the signal output from the 16Hz signal detection circuit; (E) the signal output from the OR circuit and the signal output from the loop detection circuit; an AND circuit that outputs a logical product with the signal
(F) A relay that is operated by the output of the AND circuit and connects a resistor through a contact in a loop made up of the line from the exchange and the telephone set to increase the impedance in the loop. Characteristic telephone circuit for wired broadcast telephones.