JPS60264197A - Line interface of key telephone set - Google Patents

Abstract

PURPOSE:To attain the reduction of cost and to improve the signal transmitting characteristic by constituting the titled interface that a signal at holding and calling is transmitted through a common transmission circuit and a common connecting circuit and no DC component is flowed to a transformer T of the transmission circuit. CONSTITUTION:In holding a line temporarily during talking, a relay contact a0 is closed, a DC bypass circuit 31 is connected to lines L1, L2, which are held by closing the lines L1, L2 in terms of DC. Then a holding tone generating circuit 33 is started by a signal (h) to generate a tone such as a holding tone, which is transmitted to the lines L1, L2 through the transformer T, a capacitor C and the relay contact a0. When the telephone set makes a call to a line, a relay A is turned on at first, a signal transmission circuit comprising the capacitor C and the transformer T is connected to the lines L1, L2, then a signal (t) starts an MF signal generating circuit 32 and it generates a DTMF (network control) signal according to the dial from the telephone set. When the DTMF signal is transmitted to the lines L1, L2, since the telephone set side is brought into a high impedance by a resistor R, the signal of a prescribed level or over is transmitted always to the lines L1, L2.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention allows a single line or a plurality of lines to be shared by more than the number of lines, and allows each phone to make calls, receive calls, and answer calls to these connected lines. -Relates to a line interface for a key telephone device that allows you to place calls on hold.

Structure of the conventional example and its problems FIG. 1 shows a line interface for performing transmission and holding in a conventional key telephone device. The configuration of this conventional example will be explained below with reference to FIG. 1. In the figure, 11 is the network control signal DT when the telephone calls the line.
12 is an MF signal generating circuit for generating an MF signal; 12 is a holding tone generating circuit for music, etc., which is sent to the line L2 when the telephone temporarily puts the line on hold; The MF signal generation circuit 11 is AC connected to the line L2 via the transformer T1, and the hold tone generation circuit 1
2 is also a transformer T2. Resistor R, relay contact a. .

It is connected to the line via al.

Next, the operation of the above conventional example will be explained with reference to the timing chart shown in FIG. In Figure 2, A and B respectively indicate the operation when making 2 calls while on hold.') % a
Or"1-+,')O respectively indicate the relay contacts a.r"I+bO shown in FIG.

First, when the telephone puts a busy line on hold, the relay contact a is activated. A relay (not shown) that drives +"I operates, and a DC loop is formed through the path of relay contact a. → resistor R → transformer T2 → relay contact a1, and the line , L2 never ends,
It will be retained as is. Then, the held tone such as music generated by the held tone generation circuit 12 is transmitted to the line L2 through the transformer T2. At this time, the relay contacts. A B relay (not shown), that is, a relay contact, drives the remains off and is not working. Then, when the telephone again grabs lines L+ and L2, the A relay turns off, and transformer T2 is also disconnected from line L+ and L2, and line L+ and L2 are disconnected.
The transmission of the hold tone for 2 is also stopped, and the telephone and the line are again in a talking state.

Also, when the telephone makes a call to line L2, the B relay, ie, the relay contact, is used. turns on, transformer T1
is inserted into the line, L2, and the DTMF signal generated by the MF signal generation circuit 11 is transferred from L1→capacitor C→
Relay contact. → Transte 1 → Line L1 on the route of L2
．． Sent to L2. At this time, A relay, that is, relay contact a. +"I remains off and does not work.

In this way, even in the conventional system, the operations during hold and call are performed at completely different timings, and these two operations are never performed at the same time. However, in this conventional example, the two operations are connected together, and an AC signal (i.e., one is a hold tone and the other is a DTMF signal) is sent to L2.
Despite the common □ action of sending out
Completely different sending circuits (i.e. A relay - T2 and B relay -
Tl), and the signals are sent out by their sending circuits. Therefore, the relay and the transformer are each required separately, which results in a large component package and a significant increase in cost.

Since the hold music transmission transformer T2 also flows direct current, there is a problem that a large transformer is required in order to minimize the amount of operation attenuation at the maximum current, and there is also the problem that the DTMF signal The transmitting transformer T1 similarly requires a large transformer in order to flow a direct current, and when the transformer T1 is inserted into the line LI+L2, that is, it becomes a relay contact. When the transformer T1 turns on, the back electromotive force of the transformer T1 itself tends to cause disturbances in the signal waveform, and this problem is unavoidable.

OBJECTS OF THE INVENTION The present invention eliminates the drawbacks of the above-mentioned conventional examples, and provides an excellent button telephone that has a simple configuration, reduces the number of mounted parts, is compact, reduces costs, and significantly improves signal transmission characteristics. Its purpose is to provide a line interface for devices.

Structure of the Invention In order to achieve the above object, the present invention focuses on the fact that the two circuits do not operate at the same time, and shares them in one circuit, and furthermore, the signal sending transformer is equipped with a DC component. A separate DC bypass circuit is provided to prevent the flow of the transformer, thereby making the transformer smaller, lowering the cost, and improving the transmission characteristics.

DESCRIPTION OF THE EMBODIMENTS The configuration of an embodiment of the present invention will be described below with reference to the drawings. In FIG. 3, 31 is a relay contact a. When the line is turned on, the line is connected to L2, and the line is connected to L2.
At the same time, this circuit itself is a DC bypass circuit that is set to have a high impedance in terms of AC with respect to various AC signals sent out from the transformer T, and T is a DC bypass circuit that connects the A common signal transmission transformer for signals.

This is for sending an alternating current signal to the line L2 while providing direct current insulation between the line L2 and the signal generating circuits 32 and 33. Then, the capacitor C is wired so that no direct current flows through this transformer T, and L
Relay contact a is used only to cut the DC component of 2. The DC bypass circuit 31 and the transformer T are connected to each other and connected to L2.

The resistor R is used to make the impedance on the telephone side higher than that on the line side during signal transmission, and to maintain the level of the transmitted signal above a certain value. In addition, 32 is an MP signal generation circuit that generates a DTMF signal as a network control signal when the telephone calls the line, L2, and 33 is an MP signal generation circuit that generates a hold tone, etc. for the line, L2 when the line is on hold. This is a hold tone generation circuit for sending out signals.

Next, the operation of the above embodiment will be explained with reference to the timing chart of FIG. First, if you want to temporarily put the phone on hold while talking on the line, use the hold operation on the telephone as shown in FIG. operates, and the DC bypass circuit 31 is connected to the line L2 to connect the line L2 in a direct current manner, thereby maintaining the line L2. At the same time, the hold tone generation circuit 33 sends a signal! 1, it generates a sound such as a hold tone, and transformer T, capacitor C, and relay contact a
. Through.

It is sent to line L2. At this time, since the signal t remains off, the MF signal generating circuit 32 is not loaded with this hold tone etc. in terms of alternating current. Also, when the telephone makes a call to the line, as shown in Figure 4B, relay A is turned on, and the signal sending circuit consisting of capacitor C and transformer T connects to the line. , L2, and then the MP signal generation circuit 32 is activated by the signal t and generates a DTMF signal in accordance with the dial from the telephone. When the DTMF signal is sent to the line L2, the telephone side has a high impedance due to the resistor R, so a signal above a certain level is always sent to the line L2 side. Ru. Also, at this time, contrary to when the signal is on hold, because the signal remains off, the held tone generation circuit 33 is maintained at no impedance in terms of alternating current, so that it does not become a load for the DTMF signal. ing.

In addition to the effects of the invention, as is clear from the examples, according to the line interface of the present invention, the holding and outgoing calls, which were conventionally sent out separately by individual circuits and connected to the other line through separate relay contacts, can be eliminated. It is configured so that the signal sending operation is performed by a common sending circuit and a common connection circuit, and since no DC component is allowed to flow through the transformer T of the sending circuit, the overall size is small. Moreover, it has become possible to use materials with excellent signal transmission characteristics, and the components of the entire line interface have been made smaller.

It has the advantage of simultaneously improving the mounting surface and reducing costs through sharing, and improving signal transmission characteristics through the use of a DC bypass circuit.

[Brief explanation of drawings]

FIG. 1 is an electrical connection diagram of a line interface of a conventional button telephone device, FIG. 2 is a timing chart explaining the operation of the conventional example shown in FIG. 1, and FIG. 3 is a button diagram of an embodiment of the present invention. FIG. 4 is an electrical connection diagram of the line interface of the telephone device. FIG. 4 is a timing chart diagram illustrating the operation of an embodiment of the present invention shown in FIG. 3. 31... DC bypass circuit, 32... DTMF signal generation circuit, 33... Hold tone generation circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 1-11-1-1 Daicel

Claims (1)

[Claims] A DC bypass circuit that connects in parallel to the line and closes the DC current, and at the same time has a high impedance in terms of AC so that it does not become a load on the various AC signals to be sent, and a DC bypass circuit that is parallel to the DC bypass circuit. a signal sending circuit that is inserted into the line and sends out various AC signals, and a single connection circuit common to the various signals that is inserted into the line only when the DC bypass circuit and the signal sending circuit are used to send signals to the line. A line interface for a button telephone device consisting of: