JPH01143453A - Telephone set for wired broadcast - Google Patents

Abstract

PURPOSE:To recognize the busy state of a line without hooking off a handset by providing a line polarity detection means, a counter means and a display means, starting time measurement in response to the detection of the line busy state by the polarity detection means and displaying the time on the display means so as to attain the display of the line busy state. CONSTITUTION:The line has the same polarity from dialing to the end of speech. In this case, the telephone set side utilizes it that the level of a terminal 1b at a line L2 is positive (+) at the line busy state and the line busy state is detected by a path of terminal 1b of the line L2 resistor 14 transistor 17 resistor 16 and sends a busy signal to a counter circuit 18. The counter circuit 18 starts the counter to send its data to a liquid crystal display circuit 19. Thus, the liquid crystal display circuit 19 displays the time by liquid crystal display. Moreover, the elapsed time is displayed on the liquid crystal display device of its own telephone set to recognize the minutes elapsed for the call.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a cable broadcast telephone used in a cable broadcast telephone system, and particularly to a cable broadcast telephone suitable for use when a large number of telephones are jointly connected to a line. related to telephones.

[Conventional technology]

Conventionally, the line busy display function of this type of cable broadcasting telephone has been provided by the following means.

That is, even when the user picks up the handset, the user is notified that the phone is busy by muting the phone, or conversely, this is notified by generating a busy tone within the phone and forcing the phone to pick up the phone. There is also a system that detects the polarity of the line with a meter such as a voltmeter, and uses a busy meter to indicate when the line is busy.

[Problem that the invention seeks to solve]

However, with such methods,
There are problems such as inconvenience for the user.

In other words, the line busy display function of the conventional cable broadcasting telephone mentioned above depends on sound like the former, that is, when the line is opened by sound (silence, busy tone) from the receiver, the line busy display function is not actually activated by the user. The drawback is that you won't hear when the line is busy unless you pick up the receiver. In particular, when a line is connected to a large number of telephones, the line is busy for a long time, so when using such a method, you have to repeatedly pick up the receiver and check if the line is free. It is time consuming and inconvenient.

In addition, with the latter method, i.e., telephones that use a busy meter to indicate that the line is busy, you can tell whether the line is busy by looking at the position of the meter's needle without having to lift the handset, but the busy meter is expensive. Another disadvantage is that it is easily broken because it has mechanical parts.

Furthermore, although the busy meter shows when the line is busy, it does not tell you how long the line has been busy.
Since it was not possible to estimate the time when the line would become empty, there was still a problem in that it was inconvenient for the users.

An object of the present invention is to provide a cable broadcasting telephone that not only allows you to know when a line is busy without picking up the receiver, but also allows you to estimate how long it will be before the line becomes available.

[Means for solving problems]

The present invention connects a plurality of telephones together to a two-wire line between an exchange and a telephone, and the exchange inverts the polarity of the line between standby and other states, thereby allowing each telephone to communicate privately. In a cable broadcasting telephone set having a function, a polarity detecting means for detecting the polarity of the line, a counter means operated in accordance with the detection output of the line in use by the polarity detecting means, and an output of the counter means. The present invention is characterized by comprising a display means for displaying the time and for displaying the time display as a line busy display.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block circuit diagram of an embodiment of the present invention,
A wired system in which there is a two-wire system between the exchange and the telephone, and multiple telephones are connected to that line, and the exchange reverses the polarity of the line between standby and other states, giving each telephone a secret call function. This figure shows a case in which a broadcast telephone visually displays a busy line, displays the time, and uses a liquid crystal as the display means.

In Fig. 1, numerals 1a and lb are terminals for connection to a two-wire line, and the polarity of these terminals is positive (+) on the 1st side of the line during standby and positive (+) on the 2nd side of the line. On the other hand, when the line is busy, the 1st side of the line becomes negative (-) and the 2nd side of the line becomes positive (+), so switching occurs accordingly.

The terminal 1a is connected to one end of a diode bridge 9 via a hook switch (H3) 2 and further via diodes 5.7 connected in series with the polarities shown. A series connection circuit of relay (A) 3 and diode 6 is connected in parallel to both ends of diode 7, and a connection point between relay 3 and diode 6 and a connection point between hook switch 2 and diode 5 are connected in parallel. A series connection circuit of the diode 8 and the relay contact 4 of the relay 3 is inserted between them.

On the other hand, the terminal 1b is connected to the other end of the diode bridge 9.

On the output side of the diode bridge 9, there are a dial circuit 10, a call circuit 11, and a counter circuit 18 as shown in the figure.
, a liquid crystal display circuit 19 is provided as a display means. The liquid crystal display circuit 19 is operated by the operation of the counter circuit 18, and as described later, displays the time and indicates that the circuit is busy. Further, the operation of the counter circuit 18 is controlled by the detection output of the circuit that detects the polarity of the line described above. In this embodiment, the polarity detection circuit for this purpose includes a transistor 17 whose base voltage is controlled by the polarity on the line 2 connected to the terminal 1b, and a resistor 14.1 in the base circuit.
5 and a collector resistor 16, and the collector output of the transistor 17 is applied to the counter circuit 18 as a control signal.

In the figure, 13 is a battery, and 12 is a diode. The diode 12 is provided to prevent the voltage of the battery 13 from being applied to the line side.

In this way, in this embodiment, there are two connections between the exchange and the telephone.
In wire broadcasting telephones, multiple telephones are jointly connected to the line, and the exchange reverses the polarity of the line between standby and other states, giving each telephone a secret function. It has a polarity detection circuit, a counter circuit 18, and a liquid crystal display circuit 19, and when the polarity detection circuit detects that the line is in use, it operates a timer circuit to display the time on the liquid crystal display circuit 19 to indicate that the line is busy. It is configured as follows.

Further, the operation thereof will be explained below.

First, as described above, the polarity of the line is positive (+) on the line L side during standby, and negative (-) on the line 2 side. When you pick up the handset to make a call in this state, the hook switch (H3) 2 closes, and the following changes occur: diode 5 → relay 3 → diode 6 → diode bridge 9 - dial circuit 10 - call circuit 11 → diode bridge 9 → Current flows through the route of terminal 1b on the line L2 side, and the exchange recognizes that the telephone receiver has been picked up. Next, the exchange reverses the polarity of the line, making the line 2 side positive (+) and the line L side negative (-). As a result, the current now flows from the terminal 1b of the example 54752 to the diode bridge 9→
Dial circuit 10 -> Call circuit 11 -> Diode bridge 9 -> Diode 7 - Relay 3 - Diode 8 -> Relay contact (A contact) 4 - Hook switch 2 -> Line L, the flow follows the route of terminal 1a on the side, so that relay 3 maintain self. Here, even if the other telephone in the communal connection picks up the handset, the relay contact (A contact) 4 is open, so the relay 3 will not operate and the line will not be connected (secrecy function).

From now on, the polarity of the line will remain the same from dialing until the end of the call. At this time, on the telephone side, taking advantage of the fact that terminal 1b on the line 2 side becomes positive (+) when the line is busy,
Terminal 1b on line 2 side → Resistor 14 - Transistor 17
→The resistor 16 detects that the line is busy and sends a busy signal to the counter circuit 18.

Then, the counter circuit 18 starts a counter and sends the data to the liquid crystal display circuit 19. As a result, the liquid crystal display circuit 19 displays time using a liquid crystal display. Here, both the counter circuit 18 and the liquid crystal display circuit 19 are operated in batch January 3. When the call ends, the exchange returns the polarity of the line to the standby state, so the terminal 1b on the second side of the line becomes positive (+), the transistor 17 turns off, and a signal is sent to the counter circuit 18 that the line is empty. send. The liquid crystal display circuit 19 turns off the time display in response to this signal. The liquid crystal display circuit 19 can then display the time.

In addition, since the calling party operates in exactly the same manner as described above, the elapsed time is displayed on the liquid crystal display of his/her own telephone, so that he/she can see how many minutes the call has lasted.

〔Effect of the invention〕

As described above, the present invention includes a line polarity detection means, a counter means, and a display means, and starts time measurement when the polarity detection means detects that the line is in use. By displaying the time on the display means to indicate that the line is busy, it is possible to know when the line is busy without lifting the receiver, and since the time is displayed, it is also possible to estimate how long it will take for the line to become free. Furthermore, if a liquid crystal display circuit is used as the display means, high reliability can be obtained since there is no mechanical component like a conventional busy meter.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram of a cable broadcasting telephone with a line busy display function showing an embodiment of the present invention. la, lb...Terminal 2...Hook switch 3...Relay 4...Relay contacts 5-8, 12...Diode 9...Diode bridge 10... ... Dial circuit 11 ... Call circuit l3 ... ... Battery 14 to 16 ... Resistor 17 ... Transistor 18 ... Calculation circuit 19 ... Liquid crystal display Circuit agent Patent attorney Yoshiyuki Iwasa

Claims (2)

[Claims] (1) Multiple telephones are jointly connected to a two-wire line between an exchange and a telephone, and the exchange reverses the polarity of the line between standby and other states, giving each telephone a secret call function. A cable broadcasting telephone of a type having a polarity detecting means for detecting the polarity of the line, a counter means operating in accordance with a detection output of the polarity detecting means when the line is in use, and a timer according to the output of the counter means. 1. A cable broadcasting telephone characterized by comprising display means for displaying the time and displaying the time as a line busy display. (2) The cable broadcasting telephone set forth in claim 1, wherein the display means is a liquid crystal display circuit.