KR0135656B1 - Method of electronically howling prevention in the switching - Google Patents

Abstract

1. the technical field to which the invention described in the claims belongs; A technology related to a doaphone circuit that is interlocked with a simple exchange.

2. The technical problem to be solved by the invention; Provided is a method for preventing electrical howling in a doorphone connection circuit of a simple type exchanger.

3. Summary of the Solution of the Invention; Supplying power to the dog phone by generating a power control signal in response to the call detection signal of the dog phone; The step of transmitting the held sound by maintaining the same impedance as the call of the exchange via the network.

4. Significant use of the invention; It is suitably used to prevent electrical howling in doaphone connection circuit of simple type exchanger.

Description

How to Prevent Electrical Howling in Doorphone Connection Circuit of Simple Exchange

1 is a block diagram of a doaphone connection circuit according to the prior art,

2 is a phone connection circuit diagram according to the present invention,

3 is an operation control flowchart of the control unit in FIG. 2.

The present invention relates to a doaphone connection circuit of a simple type exchanger, and more particularly, to a method capable of preventing electrical howling by improving impedance mismatch generated when connecting a doaphone.

In general, a simple exchange, which is a type of private switching system, is connected to a door phone to achieve communication of a call. Howling is generated when increasing the transmission and reception sensitivity of the doaphone due to impedance mismatch when connecting the doaphone in the conventional type exchanger used in the related art. Although there is no howling due to acoustic coupling by the instrument, electric impedance mismatch could not obtain sufficient transmit / receive sensitivity of the doaphone, which will be described with reference to FIG.

Referring to FIG. 1, a simple switch comprising a control unit 4, a network circuit 10, a simple switch subscriber 2, and a music source 6 is connected to a doaphone 14 through a doaphone call connection 12. When the doaphone is connected in the simple exchange, power is supplied to operate the doaphone. When the doaphone is not normally used, there is no part connected to the voice call circuit. Well that's over. This is in the state where all connection points are separated in FIG. In addition, when calling the simple switch in Doaphone 14, the control unit 4 detects this and gives a beep sound notifying that the Doaphone has been called, and transmits music to the Doaphone indicating that the exchange signaled the call. The music source that transmits music in the conventional doaphone connection circuit is connected to the output terminal of the OP amplifier 8, wherein the impedance of the circuit connected to the doaphone is nearly zero as the output impedance of the OP amplifier. This is with connection point X1 closed in FIG. In addition, the connection point X3 is closed in Fig. 1 when the simple switch and the phone are in communication, and the impedance of the simple switch and the phone is typically 600 ohms. Therefore, the impedance seen from the Doaphone toward the simple exchange appears in three types: 0 ohms and 600 ohms, the impedance of the calls over 100 kilo ohms.

The return loss at this time

Therefore, when a doaphone is connected and used in a simple type exchanger, three types of impedances exist in the related art as described above. There was a problem that can not greatly increase the transmission and reception sensitivity.

Accordingly, an object of the present invention is to reduce the howling due to electrical characteristics and to sufficiently increase the transmission and reception sensitivity of the door phone by controlling the optimum impedance matching and the operating voltage of the door phone in all conditions in the door phone connection device of the simple exchanger. Is to provide a way to.

According to the present invention for achieving the above object, a method for preventing electrical howling in the doaphone connection circuit of the simple switching device is the door phone by generating a power control signal in response to the call detection signal of the door phone Supplying power; It is characterized in that it has a step of transmitting a hold sound by maintaining the same impedance as in the call of the exchange through the network.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals have the same reference numerals as much as possible even if displayed on different drawings. In addition, in the following description, many specific details such as components of a specific circuit, for example, an operational amplifier, etc., are provided, which are provided to help a more general understanding of the present invention, and the present invention may be practiced without these specific details. Will be apparent to those of ordinary skill in the art. In describing the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description will be described.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. In particular, in the embodiment of the present invention, but the case of the doaphone, but can be applied in the same manner in the same field. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by the equivalents of the claims.

2 is a circuit diagram of the present invention. In FIG. 2, the power supply control unit 104 and the impedance matching unit 102 are added in addition to the configuration of FIG. Therefore, when waiting for a doaphone call, the state is not supplied with power from the simple switch, thereby eliminating the howling occurring in the call waiting state of the conventional doaphone. The impedance matching unit 102 connected to the music transmission source 6 performs impedance matching by maintaining the same impedance at the time of listening to music on the phone and during a call, thereby sufficiently increasing the transmission / reception sensitivity of the phone.

In the connection of a doaphone having the configuration as shown in FIG. Accordingly, the Doaphone call connection unit 12 applies the call detection signal to the control unit 100. In operation, the microcomputer 100 senses the signal and changes the power control signal from a low level to a high level during call waiting. Therefore, the high signal is applied to the base of the transistor Q1 in the power control section 104. When a high signal is applied to the base of the transistor Q1, the transistor is turned on, and the transistor Q2 is turned on as the collector of the transistor Q1 falls to a low level. In this case, resistor R1 should be set to a resistor value that allows Q2 to flow enough current to the doaphone. In a state where power is supplied to the door phone, the controller 100 connects an X2 contact in the network circuit 10. When the music provided from the music source 6 is sent to the door phone, the resistor Z1 connected to the output terminal of the OP amplifier 8 becomes the output impedance at the time of music delivery. At this time, if Z1 is equal to the impedance of the exchange during the telephone call, the impedances during the transmission of the call and the reserved music are the same. Therefore, the transmission / reception sensitivity of the door phone, which was a problem due to impedance mismatch, can be sufficiently increased. 3 is a flowchart of the microcomputer control according to the present invention, which implements the operation of the controller 100 as a flowchart, from step 300 to step 314.

In step 300, the control unit 100 checks whether the call detection signal is received in the connection unit 12 of FIG. Then, the power supply control signal is applied as a high level. In operation 306, if the hook-off state of the subscriber is detected and corrected, steps 308 and 310 are performed. In step 312, whether the subscriber is on-hook is checked. If the call is terminated, step 314 is performed, and the power control signal is maintained at the low level.

According to the present invention as described above, it is possible to prevent the electrical howling by improving the impedance mismatch generated during the connection of the Doaphone.

Although the above-described present invention has been described and limited by way of example with reference to the drawings, the same will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit of the present invention. .

Claims (3)

CLAIMS 1. A method for preventing electrical howling of a doaphone connection circuit of a simple switch, comprising: supplying power to the doaphone by generating a power control signal in response to a call detection signal of the doaphone; And maintaining the same impedance as in the call of the exchange via a network connection to issue a hold tone. The method of claim 1, wherein the power control signal is a voltage signal having first and second levels and is a control signal for supplying or cutting off power to the door phone. 3. The method according to claim 2, wherein the maintenance of the same impedance as in the call is achieved by an impedance matching element composed of a resistor and an operational amplifier.