JPH04131063U - speaker horn telephone - Google Patents

Abstract

(57) [Summary] [Structure] Means for detecting occurrence of howling 6
, an input/output level control means 5 that controls the input/output level based on the detection signal of the detection means 6, and level adjustment means 1 and 2 provided in the speaker circuit and microphone circuit driven by the control signal of the control means 5. It is characterized by having the following. [Effect] Even if howling occurs during a call using a speakerphone telephone, the unpleasant howling sound can be immediately prevented.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

This invention relates to a speaker horn telephone to prevent howling. be.

0002

[Conventional technology]

Conventionally, in telephones equipped with speaker horns, in order to prevent howling, Transmitting audio signal level from the microphone circuit and receiving audio signal from the speaker circuit The level of the transmitting audio signal is compared with the level of the receiving audio signal using a comparison circuit. If the signal level is too loud, insert an attenuator into the speaker circuit to reduce the received audio signal level, and vice versa. If the receiving audio signal level is higher than the transmitting audio signal level, the microphone circuit Howling can be suppressed by inserting an attenuator into the A control device has been proposed.

0003 In addition to the above devices, frequency shifting can also be applied to the microphone circuit or speaker circuit. A proposal has been made to increase the howling level by inserting a feedback circuit (Japanese Unexamined Patent Publication No. 6 4-71370).

0004

[Problem that the idea aims to solve]

This invention is designed to detect howling that occurs during a call in a speakerphone telephone. This method immediately prevents howling with a simple circuit configuration.

[0005]

[Means to solve the problem]

The present invention provides a speakerphone telephone equipped with a microphone and a speaker. Howling detection means for detecting occurrence of howling, and howling detection input/output level control means for controlling the input/output level based on a detection signal of the means; An output provided in a speaker circuit driven by a control signal of the input/output level control means. a power level adjustment means and an input level adjustment means provided in the microphone circuit. It is characterized by this.

[0006]

[Effect]

The speakerphone telephone of the present invention can prevent howling during a call.

[0007]

【Example】

Embodiments of the speakerphone telephone according to the present invention will be described below with reference to the drawings.

[0008] In Figure 1, the speaker circuit of the speakerphone telephone has a receiving audio signal output. Connect the input terminal of speaker 2 to output level adjustment means 1 for adjusting the power level, and Input level adjustment means for adjusting the input level of the transmitting audio signal is provided in the microphone circuit. Connect the output terminal of microphone 4 to 3. The above output level adjustment means 1 and input An input/output control means 5 for controlling the signal level of the level adjustment means 3 is provided.

[0009] Also, howling is detected between the speaker circuit and microphone circuit. A detection means 6 is provided. Furthermore, terminals 7 and 8 are connected to each communication path. .

0010 Next, the operation of the speaker phone telephone having the above configuration is explained in a flowchart shown in FIG. I will explain based on.

[0011] First, the user of the telephone starts a conversation with the other party through speaker 2 and microphone 4. When performing this, the frequency of the howling sound stored in advance in the howling detection means 6 Check whether there is a band component (A), and if there is no corresponding frequency component, it is howling. It is determined that this has not occurred (E).

0012 If there is a corresponding frequency component, the level of that frequency component is memorized in advance. Howling Level (B) If it is at a level above that level, it is assumed that no howling is occurring (E), and if it is at a higher level. If so, move to (C).

[0013] Check whether the howling sound is output continuously for the pre-memorized length of time. If the output is continuous, it is determined that howling is occurring (D). Also , if the howling sound is not output continuously, it is assumed that howling is not occurring. Judge (E).

[0014] With the above flow, you can determine whether it is howling (D) or not (E). A detection signal of this information is input to the input/output level control means 5. The input/output When the bell control means 5 receives a detection signal of "no howling", the output level is adjusted. without changing the degree of amplification or attenuation in the means 1 and the input level adjustment means 3, When the input/output level control means 5 receives a detection signal indicating "howling", the output level is By suppressing and lowering the amplification degree of the input level adjustment means 1 and the input level adjustment means 3, This can prevent howling noise from occurring.

[0015]

[Effect of the idea]

This invention prevents howling from occurring during calls in speakerphone telephones. Even in such cases, the unpleasant howling sound can be immediately removed.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the main structure of a speakerphone telephone according to the present invention.

FIG. 2 is a flowchart showing the operation of the speakerphone telephone according to the present invention.

[Explanation of symbols]

1 Output level adjustment means 3 Input level adjustment means 5 Input/output level control means 6 Howling detection means

Claims (1)

[Scope of utility model registration request] 1. Howling detection means for detecting occurrence of howling, input/output level control means for controlling input/output levels based on the detection signal of the howling detection means, and control signals of the input/output level control means. 1. A speaker horn telephone comprising an output level adjusting means provided in a driven speaker circuit and an input level adjusting means provided in a microphone circuit.