KR20060030948A - Audio output interface circuit of mobile communication terminal - Google Patents

Abstract

The present invention relates to a four-pole audio interface circuit having four terminals for audio input and output of a mobile communication terminal. In particular, a four-pole mono terminal of a mobile communication terminal enabling stereo earphones to be used even when the mobile communication terminal has a mono audio output. An audio output interface circuit is provided. A differential current amplifier for amplifying a mono audio output and outputting the mono audio output to the first audio terminal and the second audio terminal; A first switch for selecting the mono audio output to be connected to the second audio terminal; And a resistor comparator configured to output a control signal for determining whether the first switch is shorted based on an output value of the second audio terminal and an output value of the common ground terminal. The present invention enables the use of the stereo earphone in the mobile phone of the mono speaker output by using an electrical switch and a current amplification circuit in the mono audio output mobile phone, thereby realizing device compatibility and improved reception sound quality.

Mobile terminal, 4-pole mono audio output, earphone

Description

Interface circuit of in mono audio output mobile phone}             

1 is a diagram illustrating a structure of connecting a 4-pole mono earphone to a 4-pole stereo output mobile phone terminal according to the related art.

2 is a block diagram illustrating a mobile communication terminal according to the present invention.

3 is a view showing a structure in which a mobile communication terminal is connected to a mono ear according to the present invention;

4 is a view showing a stereo earphone connection structure according to an embodiment of the present invention

5 is a view showing a stereo earphone connection structure according to another embodiment of the present invention

6 is a view showing a stereo earphone connection structure according to another embodiment of the present invention

The present invention relates to a four-pole audio interface circuit having four terminals for audio input and output of a mobile communication terminal. In particular, a four-pole mono terminal of a mobile communication terminal enabling stereo earphones to be used even when the mobile communication terminal has a mono audio output. An audio output interface circuit is provided.

In recent years, the availability of a call when using a mobile communication terminal such as driving a vehicle is a problem. To solve this problem, a technology using an earphone such as a hands-free light has emerged.

Earphones can be divided into mono earphones having one speaker and stereo earphones having two speakers. Typically, mono earphones are used for mono audio output mobile communication terminals, and stereo earphones are used for stereo audio output mobile communication terminals.

In the prior art, when mono earphones are used in a mobile communication terminal having a stereo audio output or stereo earphones are used in a mobile communication terminal having a mono audio output, normal operation is difficult.

That is, in the mono audio output mobile communication terminal according to the prior art, the stereo earphone and the mono earphone are not compatible or only one sound is outputted when the mono earphone is used in the mobile communication terminal capable of stereo output. In addition, in the prior art, since all of the earphone terminals are different, each mobile communication terminal uses earphones having different shapes, and compatibility due to the use of different components, respectively.

1 is a diagram illustrating a structure of connecting a 4-pole mono earphone to a 4-pole stereo output mobile phone terminal according to the related art.

As shown, the stereo earphone according to the prior art has four terminals, that is, a common ground terminal, a microphone terminal, a right speaker terminal, a left speaker terminal. The structure of connecting 4-pole mono earphones to 4-pole stereo output cell phone terminals is connected in parallel because the mono output is output to two earphone speakers.

A typical speaker has an impedance of about 8 ohms, but two are connected in parallel so that the output impedance drops to about 4 ohms. This difference causes problems such as poor sound quality.

That is, in the related art, when two earphones are driven with one earphone output, a problem in output power occurs, so that the size of a voice signal is reduced, and noise is increased when using a mono earphone.

The present invention is to solve the above-mentioned problems, the use of the electrical switch and the current amplification circuit in the mono audio output cell phone to enable the stereo earphone in the mono speaker output cell phone, thereby realizing device compatibility and receiving sound quality For the purpose of improvement.                         

In order to achieve the above object, the present invention provides a differential current amplifier for amplifying a mono audio output and outputting the first audio terminal and the second audio terminal; A first switch for selecting the mono audio output to be connected to the second audio terminal; And a resistor comparator configured to output a control signal for determining whether the first switch is shorted based on an output value of the second audio terminal and an output value of the common ground terminal.

In the present invention for achieving this object, the first switch is characterized in that in the initial state to connect the second audio terminal to the common ground inside the mobile communication terminal. In the present invention for achieving this object, the resistance comparator is characterized in that for connecting the first switch to the differential current amplifier when the input value is all 0 (v).

In the present invention for achieving this object, the mono audio output interface circuit further comprises a second switch for selecting whether to interrupt the common ground terminal according to the control signal of the resistance comparator.

In the present invention for achieving this object, the mono audio output interface circuit further comprises a third switch for selecting an output of the first audio terminal. In the present invention for achieving this object, the mono audio output interface circuit further comprises a fourth switch for selecting an output of the second audio terminal.

DETAILED DESCRIPTION A detailed description of preferred embodiments of the present invention will now be described with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are used as much as possible even if displayed on different drawings. In addition, in the following description of the present invention, if 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 thereof will be omitted. The terms to be described below are terms defined in consideration of functions in the present invention, which may vary according to a user's intention or custom, and the definitions should be made based on the contents throughout the specification.

2 is a block diagram of a mobile communication terminal according to the present invention.

In the following description, the mobile communication terminal includes a cellular phone, a personal communication system (PCS), a personal data assistant (PDA), an international mobile communication-2000 (IMT2000) terminal, and the like. The following description will be described with the general configuration of the above examples.

Referring to FIG. 2, a control unit (MPU: Micro-processor unit) 24 controls the overall operation of the mobile terminal. For example, it performs processing and control for voice calls and data communications, and performs switch control and voltage gain control according to user settings in addition to the usual functions according to the present invention. Therefore, in the following description, the description about the process and control of the normal control part 24 is abbreviate | omitted.

A ROM (ROM: Read Only Memory) 02 stores microcode and various reference data of a program for processing and control of the controller 24. ROM (Read Only Memory) 02 is a nonvolatile memory that can store data regardless of whether power is supplied.

Random Access Memory (RAM) 04 is a working memory of the control unit 24. It is a volatile memory and stores temporary data generated during execution of various programs. The flash ROM 06 is a nonvolatile memory, and may be referred to as a database (DataBase) that stores various updatable data for storage such as a phone book.

The keypad (08) consists of numeric keys 0-9, menu, cancel (clear), confirmation, call (TALK), end (END), internet access, navigation keys (up / down / left). / Right) and a plurality of function keys, and provides key input data corresponding to a key pressed by the user to the controller 24.

In particular, the four navigation keys are used as shortcuts to directly enter specific menu items (eg, message management (←), phone book (→), top menu list (↑), music box (↓)). . As can be seen, a typical terminal has two keys (menu key, navigation key) for entering the top menu list.

The display unit 10 displays status information generated during the operation of the mobile communication terminal, a limited number of characters, a large amount of video and still images, and the like. The display unit 10 may use a color liquid crystal display (LCD).

The codec (Coder-Decoder) 12 connected to the control unit 24 and the speaker 16 and the microphone 14 connected to the codec 12 are voice input / output blocks used for phone calls and voice recording. . The codec 12 converts the PCM data provided from the control unit 24 into an analog voice signal and transmits it through the speaker 16, and converts the voice signal received through the microphone 14 into PCM data. It is provided to the control unit 24.

In addition, the RF unit (Radio Frequency unit) (20) is provided to the baseband processing unit 22 by lowering the frequency of the radio frequency signal received through the antenna 18, the baseband signal from the baseband processing unit 22 The frequency is raised and transmitted through the antenna 18. The baseband processor 22 processes a baseband signal transmitted and received between the RF unit 20 and the controller 24.

For example, in the case of transmission, channel coding and spreading of data to be transmitted are performed, and in the case of reception, the function of despreading and channel decoding of a received signal is performed. .

That is, the baseband processor 22 is a block for demodulating various channels (calling channel, traffic channel, etc.) received from the base station or generating various channels (access channel, traffic channel, etc.) transmitted to the base station.

3 is a diagram illustrating a structure in which a mobile communication terminal according to the present invention is connected to a mono injector.                     

Typically, a mono earphone has four terminals: a microphone (+) terminal, a microphone (−) terminal, a mono speaker (+) terminal, and a mono speaker (−) terminal. The present invention is characterized in that it comprises a resistance comparator 200 for driving the switch by comparing the audio output value and the audio output value in the audio input and output circuit of the mobile communication terminal.

The mobile communication terminal according to the present invention has a mono audio output, and accordingly, FIG. 3 shows a mono earphone connection according to the mono audio output and thus shows an optimal connection state.

As shown, when the 4-pole mono earphone is connected to the mobile communication terminal, the first switch 300 is set to be in an off state by being connected to a common ground.

Accordingly, the terminal a is connected to the ground, and 0 (v) is input to the resistance comparator 200. As a result, the mono audio signal provided by the differential current amplifier 100 constitutes a closed circuit provided through the mono speaker terminal of the mono 4-pole earjet to the common ground terminal.

In FIG. 3, the audio input circuit in the mobile communication terminal maintains a microphone signal of about 2 (v), and when an audio input is made by an external microphone, the input AC value is provided to the microphone (-) terminal in the mobile communication terminal. The signal of the second switch 400 is connected.

The second switch 400 is set to be connected to a microphone (-) terminal in the mobile communication terminal at the time of initial setting. When the resistor comparator 200 receives 0 (v) from the terminal a, the resistance comparator 200 compares the value of 2 (v) or more flowing through the terminal b and then generates a signal connecting the second switch 400 to the microphone (-) terminal. do. Accordingly, the second switch 400 is maintained in the initial connection state when the audio input by the external microphone, the microphone constitutes a closed circuit that is normally connected to the microphone (+) terminal and the microphone (-) terminal.

4 is a view showing a stereo earphone connection structure according to an embodiment of the present invention.

Stereo earphones typically have four terminals: a left speaker terminal, a right speaker terminal, a microphone terminal, and a common ground terminal. As described above, FIG. 4 is a structure in which stereo earphones are connected to a mobile communication terminal according to the present invention, and shows a connection state that can be realized by the present invention.

As shown, when the 4-pole stereo earphone is connected to the mobile communication terminal, in the initial state, the first switch 300 is connected to the terminal d to be connected to the common ground of the mobile communication terminal.

Accordingly, 0 (v) is input from the a terminal to the resistance comparator 200 according to the present invention. Also, as the b terminal of the resistor comparator 200 is connected to the common ground of the stereo earphone, 0 (v) is similarly input.

The resistance comparator 200 generates a signal connecting the first switch 300 from the d complex to the c terminal when 0 (v) is input from both the a and b terminals. When the first switch 300 is connected from the d jar to the c terminal, the mono audio signal provided from the differential current amplifier 100 is input to the left speaker through the first switch 300.

Accordingly, both the right and left speakers are provided with a mono audio signal of the mobile communication terminal.

Meanwhile, as the first switch 300 is connected to the c terminal in the d jar, a voltage flows through the a terminal of the resistor comparator 200. The resistor comparator 200 is provided with 0 (v) input from the b terminal and a voltage value input from the a terminal.

The resistance comparator 200 generates a signal connecting the second switch 400 from the e terminal to the f terminal when two different values are input. Accordingly, the microphone (+) terminal of the mobile communication terminal is connected to the microphone terminal of the stereo earphone, and the microphone (-) terminal is grounded to form a closed circuit.

5 is a view showing a stereo earphone connection structure according to another embodiment of the present invention, a circuit implemented to use only the right speaker by the user selection.

5 is the same as the stereo earphone connection structure according to an embodiment of the present invention, as shown in Figure 4, and further comprises a third switch 500 for selecting whether to drive the left speaker It is characterized by.

The third switch 500 may be implemented by H / W in the mobile communication terminal, or may be implemented by menu selection in S / W. The user may select the third switch 500 to be connected to the h terminal, and output the audio only by the right speaker even though the stereo earphone is used.

If the user wants a normal stereo output, the user selects the third switch 500 to be connected to the g terminal.                     

On the other hand, the initial setting of the third switch 500 is assumed to be in an ON state, that is, a state connected to the terminal g. Therefore, in the initial state, FIG. 5 follows the same operation process as described with reference to FIG. 4.

In other words, when the 4-pole stereo earphone is connected to the mobile communication terminal, in the initial state, the first switch 300 is connected to the terminal d so as to be connected to the common ground of the mobile communication terminal, so that the resistance comparator 200 has a terminal. 0 (v) is input. Also, as the b terminal of the resistor comparator 200 is connected to the common ground of the stereo earphone, 0 (v) is similarly input.

The resistance comparator 200 connects the first switch 300 to the c terminal from the d complex when 0 (v) is input from both the a and b terminals, and the differential current amplifier 100 connects the mono audio signal to the left speaker. Enter

Accordingly, both the right speaker and the left speaker are provided with the mono audio signal of the mobile communication terminal, but if the user connects the third switch 500 to the h terminal, the left speaker does not operate.

6 is a view showing a stereo earphone connection structure according to another embodiment of the present invention, a circuit implemented to use only the speaker selected by the user.

6 is the same as the stereo earphone connection structure according to another embodiment of the present invention, as shown in Figure 5, and further comprises a fourth switch 600 for selecting whether to drive the right speaker It is characterized by.                     

The third switch 500 and the fourth switch 600 may be implemented by H / W in the mobile communication terminal, or may be implemented by menu selection in S / W. The user may select the third switch 500 to be connected to the h terminal to output audio through only the right speaker, and the fourth switch 600 may be selected to be connected to the j terminal to block the audio output of the right speaker.

If the user wants a normal stereo output, the user selects the third switch 500 to be connected to the g terminal. On the other hand, the initial setting of the third switch 500 is assumed to be in an ON state, that is, a state connected to the terminal g. Therefore, in the initial state, FIG. 5 follows the same operation process as described with reference to FIG. 4.

In other words, when the 4-pole stereo earphone is connected to the mobile communication terminal, in the initial state, the first switch 300 is connected to the terminal d so as to be connected to the common ground of the mobile communication terminal, so that the resistance comparator 200 has a terminal. 0 (v) is input. Also, as the b terminal of the resistor comparator 200 is connected to the common ground of the stereo earphone, 0 (v) is similarly input.

The resistance comparator 200 connects the first switch 300 to the c terminal from the d complex when 0 (v) is input from both the a and b terminals, and the differential current amplifier 100 connects the mono audio signal to the left speaker. Enter Accordingly, both the right speaker and the left speaker are provided with the mono audio signal of the mobile communication terminal.

If the user connects the third switch 500 to the h terminal, the left speaker does not operate. When the user connects the fourth switch 600 to the j terminal, the right speaker does not operate. As a result, the user may select the third switch 500 and the fourth switch 600 to determine whether to operate the right speaker or the left speaker.

The technical spirit of the present invention has been described above with reference to the accompanying drawings, but this is by way of example only and not intended to limit the present invention. In addition, it is obvious that any person skilled in the art can make various modifications and imitations without departing from the scope of the technical idea of the present invention.

As described above, in the mono audio output cell phone, the stereo earphone can be used in the mono speaker output cell phone by using an electrical switch and a current amplification circuit, thereby realizing device compatibility and improving the reception sound quality.

Claims (12)

In a four-pole mono audio output interface circuit of a mobile communication terminal having a first audio terminal, a second audio terminal, a microphone terminal, and a common ground terminal, A differential current amplifier for amplifying the mono audio output and outputting the mono audio output to the first audio terminal and the second audio terminal; A first switch for selecting the mono audio output to be connected to the second audio terminal; And And a resistor comparator configured to output a control signal for determining whether the first switch is shorted based on an output value of the second audio terminal and an output value of the common ground terminal. The audio output interface circuit as claimed in claim 1, wherein the first switch connects the second audio terminal to a common ground inside the mobile communication terminal in an initial state. The audio output interface circuit of claim 1, wherein the resistance comparator connects the first switch to the differential current amplifier when all input values are 0 (v). The audio output interface circuit as claimed in claim 1, wherein the mono audio output interface circuit further comprises a second switch for selecting whether or not to interrupt the common ground terminal according to a control signal of the resistance comparator. 2. The audio output interface circuit of claim 1, wherein the mono audio output interface circuit further comprises a third switch for selecting an output of the first audio terminal. The audio output interface circuit as claimed in claim 1, wherein said mono audio output interface circuit further comprises a fourth switch for selecting an output of a second audio terminal. A mobile communication terminal having a four-pole mono audio output interface circuit comprising a first audio terminal, a second audio terminal, a microphone terminal, and a common ground terminal. A differential current amplifier for amplifying the mono audio output and outputting the mono audio output to the first audio terminal and the second audio terminal; A first switch for selecting the mono audio output to be connected to the second audio terminal; And And a mono audio output interface circuit including a resistance comparator for outputting a control signal for determining whether the first switch is shorted based on an output value of the second audio terminal and an output value of the common ground terminal. Terminal. The mobile communication terminal of claim 7, wherein the first switch connects the second audio terminal to a common ground inside the mobile communication terminal in an initial state. The mobile communication terminal of claim 7, wherein the resistance comparator connects the first switch to the differential current amplifier when the input values are all 0 (v). 8. The mobile communication terminal of claim 7, wherein the mono audio output interface circuit further comprises a second switch for selecting whether or not to interrupt the common ground terminal according to a control signal of the resistance comparator. 8. The mobile communication terminal of claim 7, wherein the mono audio output interface circuit further comprises a third switch for selecting an output of the first audio terminal. 8. The mobile communication terminal of claim 7, wherein the mono audio output interface circuit further comprises a fourth switch for selecting an output of a second audio terminal.

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