CN101527801A - Circuit for mixture output of TV receiver and speaker - Google Patents

Abstract

The invention discloses a circuit for mixed output of TV earphones and speakers, including a TV MCU and a small audio signal processing chip for processing external mute signals and external audio signals, and outputting MCU mute signals and small audio signals, and a TV MCU and audio signal processing chip. The small signal processing chip is connected to the speaker audio signal amplifier and the headphone audio signal amplifier for amplifying small audio signals, and is used to process the headphone detection signal and the MCU mute signal, and output control signals to control the state of the speaker audio signal amplifier and the headphone audio signal amplifier signal identification circuit; in addition, the earphone socket is also connected with an earphone detection circuit for detecting whether an earphone is inserted into the earphone socket. The invention adopts the earphone socket without control pin and the audio signal paths of the speaker and the earphone are not on the same line, so as to ensure the mixed output of the TV earphone and the speaker, and the performance is stable and reliable.

Description

Mixed output circuit of TV earphones and speakers

【Technical field】

The invention relates to the technical field of televisions, in particular to a circuit for mixed output of television earphones and speakers.

【Background technique】

With the development of science and technology and the improvement of people's living standards, LCD TVs (LCD TVs) have gradually replaced picture tube TVs (CRT TVs) and entered thousands of households. At the same time, the headphone function has also become an important function of LCD TVs. Therefore, for a TV set with earphone function, the mixed output problem of its speaker and earphone audio must be handled well, that is, when an earphone is inserted, the speaker output should be converted to the earphone output. And mainly handle by following two kinds of methods at present: 1) headphone jack is connected and cut off the loudspeaker audio signal path by mechanical action as switch, and loudspeaker and earphone audio signal path are on the same line. When there is no headphone plugged in, the switch in the headphone socket is mechanically connected, and the audio signal enters the speaker audio signal amplifier through the headphone terminal, and the speaker outputs; when a headphone is plugged in, the switch in the headphone socket is mechanically disconnected, cutting off the audio signal from entering the speaker audio signal amplifier The channel, the speaker has no output, and the audio signal is output to the earphone through the earphone jack. 2) When using the headphone jack with control pins, the audio signal paths entering the speakers and headphones are not on the same line. When there is no earphone plugged in, the speaker audio signal amplifier works normally, and the speaker outputs; when the earphone is plugged in, the state of the control pin of the headphone jack changes, and the TV MCU judges the state of the control pin, so that the speaker audio signal amplifier is in a mute state, and the speaker has no output , the audio signal is output to the earphone through the earphone jack. However, there are some defects in the above two methods, wherein, the first method is to avoid sound interference and avoid excessive wiring on the TV circuit board, the earphone jack and the speaker audio signal amplifier should be placed in adjacent positions, which limits the TV The circuit board layout of the TV set limits the appearance and structure of the TV set. And the second method adopts the earphone socket with control pin, and its cost is high, often can have unreliable, undurable defect in the use process, needs to occupy the resource of TV MCU simultaneously.

【Content of invention】

In order to solve the above problems, the main purpose of the present invention is to provide a circuit for mixed output of TV earphones and speakers, so as to ensure the mixed output of TV earphones and speakers.

To achieve the above object, the technical solution of the present invention is: a circuit for mixed output of TV earphones and loudspeakers, including a TV MCU and audio small signal for processing external mute signals and external audio signals, and outputting MCU mute signals and small audio signals. Signal processing chip, connected with TV MCU and audio small signal processing chip to amplify audio small signal speaker audio signal amplifier and headphone audio signal amplifier, and used to process headphone detection signal and MCU mute signal, and output control signal to control speaker audio signal A signal identification circuit for the state of the amplifier and the earphone audio signal amplifier; in addition, the earphone jack is also connected with an earphone detection circuit for detecting whether an earphone is inserted into the earphone jack.

Compared with the prior art, the circuit for mixed output of TV earphones and speakers in the present invention adopts an earphone socket without a control pin, and the audio signal paths of the speaker and earphones are not on the same line, so as to ensure the mixed output of TV earphones and speakers with stable performance reliable.

【Description of drawings】

Fig. 1 is a functional block diagram of the present invention.

Fig. 2 is a circuit connection diagram of the MCU, the audio small signal processing chip, the speaker audio signal amplifier and the earphone audio signal amplifier of the present invention.

Fig. 3 is a schematic circuit diagram of the earphone detection circuit of the present invention.

Fig. 4 is a schematic circuit diagram of the signal identification circuit of the present invention.

【Detailed ways】

Please refer to shown in Fig. 1, a kind of TV earphone and loudspeaker mixed output circuit of the present invention, include and be used to process external mute signal and external audio signal, and output the TV MCU of MCU mute signal and audio frequency small signal and audio frequency small signal processing chip , connected with the TV MCU and audio small signal processing chip to amplify the audio small signal speaker audio signal amplifier and earphone audio signal amplifier, and used to process the earphone detection signal and MCU mute signal, and output control signals to control the speaker audio signal amplifier and earphones A signal identification circuit for the state of the audio signal amplifier. In addition, a speaker socket is connected to the speaker audio signal amplifier for connecting a speaker; an earphone socket is connected to the earphone audio signal amplifier for connecting earphones. The earphone jack is also connected with an earphone detection circuit for detecting whether an earphone is inserted into the earphone jack.

The external AUDIO signal is an audio signal output from a signal source (such as an external TV, DVD) to the TV, and the external mute signal is a mute signal command sent by the remote control of the TV. After the external AUDIO audio input signal of the TV is processed by the small audio signal processing chip, the small audio signal AUD_SS is obtained. Among them, one small audio signal AUD_SS is amplified by the speaker audio signal amplifier to become the AUD_SPK audio signal, which is output to the speaker of the TV through the speaker socket; and the other small audio signal AUD_SS is amplified by the earphone audio signal amplifier to become the AUD_EAR audio signal. Output to headphones through the headphone jack. After the external mute signal is processed by the MCU, the TV mute signal MCU_MUTE is output, and this signal is input to the signal identification circuit; the signal PUSH_POP indicating whether there is an earphone inserted in the earphone jack is input to the earphone detection circuit; the earphone detection signal DET_S output by the earphone detection circuit enters the signal identification circuit; The signal recognition circuit outputs a speaker mute signal SPK_MUTE to control the state of the speaker audio signal amplifier, and outputs an earphone mute signal EAR_MUTE to control the state of the earphone audio signal amplifier.

PUSH_POP DET_S MCU_MUTE EAR_MUTE SPK_MUTE 0 1 0 0 1 0 1 1 0 0 1 0 0 1 0 1 0 1 0 0

The table shows the logical relationship between each signal. When there is an external mute signal, MCU_MUTE is "1" (high level is greater than 2.4V), then SPK_MUTE and EAR_MUTE are "0" (low level is less than 0.8V), and the speaker The audio signal amplifier and the earphone audio signal amplifier are in the MUTE state, and there is no AUD_SPK and AUD_EAR audio signal output. At this time, no matter whether there is an earphone plugged in, the TV is in the mute state. When there is no external mute signal, MCU_MUTE is "0" (low level), the TV will have a speaker output if there is no headphone plugged in, if there is a headphone plugged in, it will immediately switch to the headphone output, and if the headphone is pulled out, it will immediately switch to the speaker output. Specifically: when the earphone is inserted, that is, when PUSH_POP is "1", the earphone detection signal DET_S is "0", EAR_MUTE is "1", SPK_MUTE is "0", the earphone audio signal amplifier does not enter the MUTE state, and the speaker audio signal amplifier is in MUTE state, only AUD_EAR audio signal output, no AUD_SPK audio signal output; and when there is no earphone plugged in, that is, PUSH_POP is "0", the earphone detection signal DET_S is "1", EAR_MUTE is "0", SPK_MUTE is "1", and the speaker audio The signal amplifier does not enter the MUTE state, the headphone audio signal amplifier is in the MUTE state, only the AUD_SPK audio signal is output, and there is no AUD_EAR audio signal output.

Fig. 2 is a circuit connection diagram of the MCU, the audio small signal processing chip, the speaker audio signal amplifier and the earphone audio signal amplifier of the present invention. Wherein, the MUTE pins of the headphone audio signal amplifier U1 and the speaker audio signal amplifier U19 are in a normal amplification state when the level is high, and are in a mute state when the level is low. The input external AUDIO signal is processed by the small audio signal and then the audio signal AUD_SS is output. The left and right audio signals are AUD_SS_L and AUD_SS_R respectively, which are small audio signals. The audio signal AUD_SS is divided into two channels, one is input to the speaker audio amplifier U19 through the resistor R781, the resistor R782, and the capacitor C182, and the capacitor C183. After being amplified by the speaker audio amplifier U19, the differential audio signal AUD_SPK is output. The left and right audio signals are AUD_SPK_L+, AUD_SPK_L- and AUD_SPK_R+, AUD_SPK_R-, this signal is output to the speaker of the TV through the speaker socket CON3, CON4; and the other audio signal AUD_SS is input to the headphone audio signal amplifier U1 through the resistor R783, the resistor R784, and the capacitor C7 and capacitor C8. The audio signal amplified by the headphone audio signal amplifier passes through the DC isolation of capacitor C4 and capacitor C6 and then outputs the audio signal AUD_EAR. The left and right audio signals are AUD_EAR_L and AUD_EAR_R respectively. This signal is output to the earphone through the earphone jack. Since the maximum output power of the TV speaker audio signal amplifier is generally above 2W, the impedance of the TV speaker is generally 8 ohms, while the maximum output power of the headphone audio signal amplifier is generally about 0.1W, and the headphone impedance is generally 16 or 32 ohms, so the circuit The mid-speaker audio signal amplifier U19 is powered by 12V, and the headphone audio signal amplifier U1 is powered by 5V.

The remote control of the TV sends a mute command. After being processed by the motor MCU, the MCU_MUTE output from the P1 port of the MCU and the audio small signal processing chip U0 is at a high level, and the SPK_MUTE and EAR_MUTE will be at a low level at the same time, and the MUTE of the speaker audio signal amplifier Pin (pin 6) and the MUTE pin (pin 2) of the headphone audio signal amplifier are low level, so that it is in the MUTE state, that is, the audio signal attenuation is 0, there is no AUD_SPK and AUD_EAR audio signal output, and the TV enters mute state. When the remote control of the TV does not send a mute command, the MCU_MUTE output from the P1 port of the MCU and the audio small signal processing chip U0 is at a low level, and the TV does not enter the mute state. At this time, if no earphone is plugged in, the SPK_MUTE is at a high level , and EAR_MUTE is low level, the MUTE pin of the speaker audio signal amplifier is high level and the MUTE pin of the headphone audio signal amplifier is low level, only AUD_SPK audio signal output, no AUD_EAR audio signal output; if there is an earphone plugged in, EAR_MUTE is high level, while SPK_MUTE is low level, the MUTE pin of the headphone audio signal amplifier is high level and the MUTE pin of the speaker audio signal amplifier is low level, only AUD_EAR audio signal output, no AUD_SPK audio signal output.

3 is a schematic circuit diagram of the earphone detection circuit of the present invention, including an NPN transistor Q8, one end of which is grounded, and the other end is respectively connected to the earphone jack resistor R18, resistor R19, capacitor C11, and capacitor C10. The emitter of the transistor Q8 is grounded, and the base is divided into two circuits through the resistor R21, one of which is connected to the earphone jack, and the other is connected to the power supply VCC through the resistor R20. A capacitor C13 is also connected between the base and the emitter of the transistor Q8, and the headphone detection signal DET_S is output from the collector of the transistor Q8. The left and right audio signals AUD_EAR_L and AUD_EAR_R output by the headphone audio signal amplifier U1 are respectively connected to the 4th and 2nd pins of the headphone jack. When there is no earphone plugged in, the 3rd pin of the earphone jack is connected to the 4th pin, and the 5th pin is connected to the 2nd pin. Open, 3 and 4 pins, 5 and 2 pins are disconnected. Capacitor C11 and capacitor C10 are about 1000PF to prevent the AUD_EAR audio signal from entering the earphone and causing noise when there is an interference signal. When no earphone is inserted into the earphone jack, pins 3 and 4, and pins 5 and 2 of the earphone jack are connected, resistor R18 is connected in parallel with resistor R19, and the parallel resistor is connected in series with resistor R20. Select resistors R18 , R19 , and R20 with appropriate resistances so that the DC voltage of PUSH_POP is low after voltage division, that is, the DC voltage at the base of the transistor Q8 is low. At the same time, to avoid the influence of the AUD_EAR audio signal when the earphone is pulled out, select a resistor R21 with an appropriate resistance value and a capacitor C13 with an appropriate capacitance value to form an RC filter. The DC voltage at the base of transistor Q8 has no effect. The transistor Q8 is not turned on, and the headphone detection signal DET_S is at a high level. After the earphone is pulled out, the earphone detection signal DET_S is always at a high level, and the audio signal amplifier of the earphone is in a mute state with no output, which can reduce power consumption.

When an earphone is inserted into the earphone jack, pins 3 and 4, and pins 5 and 2 of the earphone jack are popped up, and pins 4 and 2 of the earphone jack are connected to the inserted earphone, and the AUD_EAR audio signal is output to the earphone. The 3 and 5 pins of the headphone jack are suspended in the air. At this time, the 5V power supply through the effect of the resistor R20, the resistor R21 and the transistor Q8 makes PUSH_POP at a high level, the transistor Q8 is saturated and turned on, and the earphone detection signal DET_S is at a low level. In order to avoid excessive current when the triode Q8 is turned on in saturation, the resistance value of the pull-up resistor R22 is selected as 10k.

Fig. 4 is a schematic circuit diagram of the signal recognition circuit of the present invention, which includes a triode Q1 connected to the earphone detection signal DET_S through a resistor R4, a resistor R11, a diode D1, and a diode D2 respectively connected to the earphone detection signal DET_S and the mute signal MCU_MUTE The transistor Q3 and the transistor Q5 are respectively connected to the collector of the transistor Q1 and the mute signal MCU_MUTE through a resistor R12 , a diode D2 , and a diode D4 . Wherein, the collectors of the transistor Q1, the transistor Q3, and the transistor Q5 are respectively connected to the power supply VCC through the resistor R1, the resistor R8, and the resistor R6. The emitters of the triode Q1, the triode Q3, and the triode Q5 are grounded. The earphone mute control signal EAR_MUTE and the speaker mute control signal SPK_MUTE are respectively output from the collectors of the transistor Q3 and the transistor Q5. When there is an external mute signal, the mute signal MCU_MUTE output by the MCU from the P1 port is at a high level. At this time, no matter whether DET_S is at a high level or a low level, that is, no matter whether there is an earphone plugged in, the diodes D3 and D4 are always on. Transistor Q3 and transistor Q5 are saturated and turned on, the speaker mute control signal SPK_MUTE and the earphone mute control signal EAR_MUTE are at low level, the speaker and the earphone audio signal amplifier are both in the mute state, there is no audio signal output, and the TV is in the mute state. When there is no external mute signal, the mute signal MCU_MUTE output by the MCU from the P1 port is at low level, and diode D3 and diode D4 are not conducting. At this time, if no earphone is inserted, DET_S is at high level, and diode D1 and transistor Q1 are conducting. Transistor Q3 is saturated and conduction, while transistor Q5 is not conducting, the speaker mute control signal SPK_MUTE output is high level and the earphone mute control signal EAR_MUTE is low level, the speaker audio signal amplifier works normally and has audio signal output, while the earphone audio signal amplifier In the mute state, there is no audio signal output; if there is an earphone plugged in, DET_S is low level, the transistor Q1 is not conducting, the transistor Q3 is not conducting, the transistor Q5 is saturated and conducting, the speaker mute control signal SPK_MUTE output is low level and the earphone is muted When the control signal EAR_MUTE is at a high level, the speaker audio signal amplifier is in a mute state and has no audio signal output, while the headphone audio signal amplifier works normally and has audio signal output.

To sum up, the circuit for the mixed output of TV earphones and speakers of the present invention can correctly switch between the output of TV earphones and speakers, realize the mixed output of TV earphones and speakers, and ensure the normal and reasonable operation of TV earphones and speakers. work.

The preferred embodiments described above are only illustrative and illustrative of the invention, but are not limited to any specific form disclosed, as many modifications and variations are possible.

Claims (9)

1. A circuit for TV earphone and loudspeaker mixed output, comprising a loudspeaker jack and an earphone jack, characterized in that: it also includes a TV MCU for processing external mute signals and external audio signals, and outputs MCU mute signals and audio frequency small signals Speaker audio signal amplifier and headphone audio signal amplifier connected with small audio signal processing chip, TV MCU and audio small signal processing chip to amplify small audio signal, and used to process headphone detection signal and MCU mute signal, and output control signal control A signal identification circuit for the state of the speaker audio signal amplifier and the earphone audio signal amplifier; in addition, the earphone jack is also connected with an earphone detection circuit for detecting whether an earphone is inserted into the earphone jack. 2. The circuit of TV earphone and loudspeaker mixed output as claimed in claim 1, is characterized in that: described loudspeaker jack is connected with loudspeaker audio signal amplifier, to be used for connecting loudspeaker; And earphone jack is connected with earphone audio signal amplifier, with For connecting headphones. 3. The circuit for the mixed output of TV earphones and speakers as claimed in claim 2, wherein the earphone detection circuit includes an NPN transistor Q8, one end of which is grounded, and the other end is respectively connected to the earphone socket resistance R18, resistance R19 and Capacitor C11, capacitor C10. 4. The circuit for mixed output of TV earphones and speakers as claimed in claim 3, characterized in that: the emitter of the triode Q8 is grounded, and the base is divided into two paths through a resistor R21, one path is connected to the earphone jack, and the other path is connected through a resistor R21. R20 is connected to the power supply VCC. 5. The circuit for mixed output of television earphones and loudspeakers as claimed in claim 4, characterized in that: a capacitor C13 is also connected between the base and the emitter of the triode Q8, and the earphone detection signal DET_S is generated by the collector of the triode Q8. output. 6. The circuit for mixed output of TV earphones and speakers as claimed in claim 5, characterized in that: the left and right audio signals AUD_EAR_L and AUD_EAR_R output by the earphone audio signal amplifier are respectively connected to the 4th and 2nd pins of the earphone jack; When the earphone is plugged in, the 3rd pin of the earphone jack is connected to the 4th pin, and the 5th pin is connected to the 2nd pin; when the earphone is inserted, the 3rd and 4th pin, the 5th pin and the 2nd pin of the earphone jack are bounced off , That is, pins 3 and 4, pins 5 and 2 are disconnected. 7. The circuit for mixed output of TV earphones and speakers as claimed in claim 6, characterized in that: said signal identification circuit includes a triode Q1 connected to the earphone detection signal DET_S through a resistor R4, a resistor R11 and a diode D1, The diode D2 is respectively connected to the transistor Q3 of the headphone detection signal DET_S and the mute signal MCU_MUTE, and the transistor Q5 is respectively connected to the collector of the transistor Q1 and the mute signal MCU_MUTE through a resistor R12 , a diode D2 , and a diode D4 . 8. The circuit for mixed output of TV earphones and speakers as claimed in claim 7, characterized in that: the emitters of the triode Q1, triode Q3, and triode Q5 are grounded, and the collectors pass through the resistors R1, R8 and R6 respectively. Connect the power supply VCC. 9 . The circuit for mixed output of TV earphones and speakers according to claim 8 , wherein the collectors of the transistors Q3 and Q5 respectively output the earphone mute control signal EAR_MUTE and the speaker mute control signal SPK_MUTE .

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