CN107360499A - Audio output balancing circuitry and earphone - Google Patents
Audio output balancing circuitry and earphone Download PDFInfo
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- CN107360499A CN107360499A CN201710668000.2A CN201710668000A CN107360499A CN 107360499 A CN107360499 A CN 107360499A CN 201710668000 A CN201710668000 A CN 201710668000A CN 107360499 A CN107360499 A CN 107360499A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R3/00—Circuits for transducers, loudspeakers or microphones
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R2430/00—Signal processing covered by H04R, not provided for in its groups
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Abstract
The invention discloses a kind of audio output balancing circuitry and earphone.The circuit includes impedance detection circuit, audio drive circuitry, resistance adjustment circuit, at least two audio output units；The resistance adjustment circuit connected in series is between the audio output and at least two audio output units of audio drive circuitry；The test side of the impedance detection circuit is connected with the audio output of the audio drive circuitry and at least two audio output unit；The control output end of the impedance detection circuit is connected with the resistance adjustment circuit；The impedance detection circuit detects the resistance between the audio drive circuitry audio output and at least two audio output units respectively, and control the resistance of the resistance adjustment circuit to export according to testing result, make it that the audio drive circuitry audio output is identical with the resistance of circuit between each audio output unit.The embodiment of the circuit can be adjusted the resistance of circuit between audio output and each audio output unit to identical.
Description
Technical Field
The present invention relates to audio processing, and more particularly, to an audio output balancing circuit and a headphone.
Background
In the existing earphones, the earphone control circuit is placed on one side of the earphones, and the distances from the earphone control circuit to the left loudspeaker and the right loudspeaker are different, so that the lengths of wires from the audio output end of the earphone control circuit to the left loudspeaker and the right loudspeaker are inconsistent. Because the wire has resistance, and then causes the audio output of earphone control circuit to the impedance of left and right loudspeaker inconsistent, causes left and right loudspeaker to output the uniformity of audio poor.
Disclosure of Invention
One objective of the present invention is to provide a new technical solution for an audio output balancing circuit, so that the resistance of the circuit between the audio output terminal and each audio output unit is the same, and the consistency of audio output between different audio output units is enhanced.
According to a first aspect of the present invention, there is provided an audio output balancing circuit, comprising an impedance detection circuit, an audio driving circuit, a resistance adjustment circuit, at least two audio output units; the resistance adjusting circuit is connected between the audio output end of the audio driving circuit and the at least two audio output units in series; the detection end of the impedance detection circuit is connected with the audio output end of the audio drive circuit and the at least two audio output units; the control output end of the impedance detection circuit is connected with the resistance adjusting circuit; the impedance detection circuit respectively detects the resistance values between the audio output end of the audio driving circuit and at least two audio output units, and controls the resistance output of the resistance adjusting circuit according to the detection result, so that the resistance values of the circuits between the audio output end of the audio driving circuit and each audio output unit are the same.
Optionally, the resistance adjustment circuit includes: at least two resistance adjustment circuits; the at least two resistance adjusting circuits are connected with the at least two audio output units in a one-to-one manner; the control output end of the impedance detection circuit is connected with the resistance adjusting circuit, and the impedance detection circuit comprises: and the control output end of the impedance detection circuit is connected with the at least two resistance adjusting circuits.
Optionally, the at least two audio output units comprise: a first audio output unit and a second audio output unit; the at least two resistance adjustment circuits include: a first resistance adjustment circuit and a second resistance adjustment circuit; the one-to-one connection of the at least two resistance adjustment circuits with the at least two audio output units includes: the first resistance adjusting circuit is connected between the audio output end of the audio driving circuit and the first audio output unit in series; the second resistance adjusting circuit is connected in series between the audio output end of the audio driving circuit and the second audio output unit.
Optionally, the output of the audio driver circuit comprises: a first audio output terminal and a second audio output terminal; the first resistance adjustment circuit is connected in series between an audio output terminal of the audio driving circuit and the first audio output unit, and includes: the first resistance adjusting circuit is connected between a first audio output end of the audio driving circuit and the first audio output unit in series; the second resistance adjustment circuit is connected in series between the audio output terminal of the audio driving circuit and the second audio output unit, and comprises: the second resistance adjusting circuit is connected in series between a second audio output end of the audio driving circuit and the second audio output unit.
Optionally, the detection terminal of the impedance detection circuit includes: a first detection end and a second detection end; the detection end of the impedance detection circuit is connected with the audio output end of the audio drive circuit and the first audio output unit and the second audio output unit, and the impedance detection circuit comprises: the first detection end of the impedance detection circuit is connected with the audio output end of the audio driving circuit and the first audio output unit, and the second detection end of the impedance detection circuit is connected with the audio output end of the audio driving circuit and the second audio output unit.
Optionally, the resistance adjustment circuit comprises a digital potentiometer.
Optionally, the impedance detection circuit comprises: the device comprises a controlled switch, a resistance measuring circuit and a control circuit, wherein the first end of the controlled switch is connected with the audio output end of an audio driving circuit, the second end of the controlled switch is connected with the resistance measuring circuit, and the control end of the controlled switch is connected with the control circuit; the resistance adjusting circuit and the resistance measuring circuit are connected with the control circuit; the control circuit is configured to control the controlled switch to conduct a circuit between the audio output end of the audio driving circuit and the resistance measuring circuit when the resistance value between the audio output end of the audio driving circuit and the at least two audio output units needs to be detected, and adjust the resistance output of the resistance adjusting circuit according to the measuring result fed back by the resistance measuring circuit.
According to a second aspect of the invention, there is provided a headset comprising the circuit as described above.
Optionally, the earphone device further comprises an earphone control chip, and the impedance detection circuit is integrated in the earphone control chip.
Optionally, the resistance adjustment circuit includes a digital potentiometer, and the digital potentiometer includes a MAX5434 chip.
The resistance adjusting circuit is connected in series between the audio output end of the audio output circuit and each audio output unit. The resistance value between the audio output end of the audio driving circuit and each audio output unit is detected through the impedance detection circuit, and the resistance output of the resistance adjusting circuit is controlled according to the resistance value. Therefore, the resistance value between the audio output end of the audio driving circuit and each audio output unit is the same, and the consistency of audio output among the audio output units is improved.
Other features of the present invention and advantages thereof will become apparent from the following detailed description of exemplary embodiments thereof, which proceeds with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention.
Fig. 1 is a block diagram of an audio output balancing circuit provided by an embodiment of the present invention.
Fig. 2 is a block diagram of an audio output balancing circuit according to another embodiment of the present invention.
Fig. 3 is a block diagram of an impedance detection circuit provided by an embodiment of the present invention.
Fig. 4(a) is a circuit diagram of a portion of the controlled switch 4s and the resistance measuring circuit 4t in fig. 3 corresponding to the first audio output terminal P1 a.
Fig. 4(b) is a circuit diagram of a portion of the controlled switch 4s and the resistance measuring circuit 4t in fig. 3 corresponding to the second audio output terminal P1 b.
Fig. 5 is a schematic diagram of an audio output balancing circuit according to another embodiment of the present invention.
Detailed Description
Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that: the relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.
The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.
Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate.
In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.
The embodiment of the invention provides an audio output balancing circuit which comprises an audio driving circuit 1, a resistance adjusting circuit 3, an impedance detection circuit 4 and at least two audio output units. The resistance adjusting circuit 3 is connected in series between the audio output terminal of the audio driving circuit 1 and at least two audio output units. The detection end of the impedance detection circuit 4 is connected with the audio output end of the audio drive circuit 1 and at least two audio output units; the control output terminal of the impedance detection circuit 4 is connected to the resistance adjustment circuit 3.
Therefore, the impedance detection circuit 4 respectively detects the resistance values between the audio output end of the audio driving circuit 1 and the at least two audio output units, and controls the resistance output of the resistance adjusting circuit 3 according to the detection result, so that the resistance values of the circuits between the audio output end of the audio driving circuit 1 and each audio output unit are the same. Thus, the consistency of audio output among the respective audio output units is improved.
Further, the at least two output units include a first audio output unit 21 and a second audio output unit 22. The first audio output unit 21 and the second audio output unit 22 may be, for example, two speakers of an earphone or two speakers of a loudspeaker box, or the like.
See fig. 1 for a block diagram of an audio output balancing circuit. The circuit comprises an audio driving circuit 1, a resistance adjusting circuit 3, an impedance detecting circuit 4, a first audio output unit 21 and a second audio output unit 22.
At this time, the audio output terminal P11 of the audio driving circuit 1 is connected to the first audio output unit 21 and the second audio output unit 22, respectively, for driving the first audio output unit 21 and the second audio output unit 22 to output audio signals.
The first audio output unit 21 and the second audio output unit 22 may share one and the same audio output terminal P11. In yet other examples, the audio output P11 includes a first audio output and a second audio output (not shown in fig. 1). The first audio output terminal is connected to and drives the first audio output unit 21, and the second audio output terminal is connected to and drives the second audio output unit 22. In an actual circuit, each audio output end comprises a positive end and a negative end, and each audio output unit is respectively connected with the positive end and the negative end of the corresponding audio output end.
The resistance adjustment circuit 3 is connected in series between the audio output terminal P11 of the audio drive circuit 1 and the first and second audio output units 21 and 22.
The resistance adjusting circuit 3 is, for example, a digital potentiometer or other device or circuit capable of being controlled to adjust its resistance output.
The impedance detection circuit 4 detects resistance values between the audio output terminal P11 of the audio drive circuit 1 and the first audio output unit 21 and the second audio output unit 22, respectively. The impedance detection circuit 4 controls the resistance output of the resistance adjustment circuit 3 according to the resistance value, so that the resistance values of the circuits between the audio output terminal P11 of the audio driving circuit 1 and the first audio output unit 21 and between the audio output terminal P11 and the second audio output unit 22 are the same. The same resistance values are not limited to absolute equality, allowing for an acceptable error range.
The circuit arranged in this way can realize impedance matching between the audio output end of the audio drive circuit and each audio output unit.
Further, the resistance adjustment circuit 3 includes: and the at least two resistance adjusting circuits are connected with the at least two audio output units in a one-to-one manner. In this case, the connection of the control output terminal of the impedance detection circuit 4 to the resistance adjustment circuit 3 includes: the control output end of the impedance detection circuit 4 is connected with at least two resistance adjusting circuits. In this way, after the impedance detection circuit 4 detects the resistance of the line between the audio output unit 2 where each audio output unit is located and the audio driver circuit 1, the resistance adjustment circuits connected in series between the audio output units 2 and the audio driver circuit 1 can be respectively adjusted, so that the resistances of the audio output ends of the audio driver circuit 1 and the circuits between the audio output units 2 are the same.
Further, when the audio output unit 2 includes the first audio output unit 21 and the second audio output unit 22, the resistance adjustment circuit 3 includes a first resistance adjustment circuit 3a and a second resistance adjustment circuit 3 b. The first resistance adjustment circuit 3a is connected in series between the audio output terminal P11 of the audio drive circuit 1 and the first audio output unit 21; the second resistance adjustment circuit 3b is connected in series between the audio output terminal P11 of the audio drive circuit 1 and the second audio output unit 22.
Further, in order to meet the requirements of users for clearer and more stereoscopic audio signals, the output audio of each audio output unit has difference, so the audio driving circuit can output different audio signals for each audio output unit. At this time, the number of the output terminals P11 of the audio driving circuit 1 is at least two, and the output terminals P11 are connected to at least two audio output units in a one-to-one correspondence.
Further, when the audio output unit 2 includes the first audio output unit 21 and the second audio output unit 22, the output terminal P11 of the audio driving circuit 1 includes: a first audio output terminal P1a and a second audio output terminal P1 b.
At this time, the first resistance adjustment circuit 3a includes, in series between the audio output terminal P11 of the audio drive circuit 1 and the first audio output unit 21:
the first resistance adjustment circuit 3a is connected in series between the first audio output terminal P1a of the audio driver circuit 1 and the first audio output unit 21.
The second resistance adjustment circuit 3b includes, in series between the audio output terminal P11 of the audio drive circuit 1 and the second audio output unit 22:
the second resistance adjustment circuit 3b is connected in series between the second audio output terminal P1b of the audio drive circuit and the second audio output unit 22.
Further, in order to more accurately measure the resistance of the circuit between each audio output terminal of the audio driver circuit 1 and the audio output unit 2, one detection terminal of the impedance detection circuit 4 may be set for the circuit between each audio output terminal and the audio output unit 2, and the circuit between each audio output terminal of the audio driver circuit 1 and the audio output unit 2 is detected respectively.
Further, when the audio output unit 2 includes the first audio output unit 21 and the second audio output unit 22, the detection terminal of the impedance detection circuit 4 includes: a first detecting terminal P41a and a second detecting terminal P41 b.
At this time, the connection of the detection terminal of the impedance detection circuit 4 with the audio output terminal P11 of the audio driving circuit 1 and the first and second audio output units 21 and 22 includes:
the first detecting terminal P41a of the impedance detecting circuit 4 is connected to the audio output terminal P11 of the audio driving circuit 1 and the first audio output unit 21, and the second detecting terminal P41b of the impedance detecting circuit 4 is connected to the audio output terminal P11 of the audio driving circuit 1 and the second audio output unit 22.
Thus, when the audio output balancing circuit includes the first audio output unit 21 and the second audio output unit 22, the impedance detecting circuit 4 detects the impedance of the circuit between the audio output terminal P11 of the audio driving circuit 1 and the first audio output unit 21 through the first detecting terminal P41 a. The impedance of the circuit between the audio output terminal P11 of the audio driver circuit 1 and the second audio output unit 22 is detected by the second detection terminal P41b, and the resistances output by the first resistance adjusting circuit 3a and the second resistance adjusting circuit 3b are adjusted according to the detection results of the first detection terminal P41a and the second detection terminal P41b, respectively, so that the impedance of the circuit between the audio output terminal P11 of the audio driver circuit 1 and the first audio output unit 21 is the same as the impedance of the circuit between the audio output terminal P11 of the audio driver circuit 1 and the second audio output unit 22.
The block diagram of the audio output balancing circuit shown in fig. 2 is an example of the circuit shown in fig. 1. The circuit comprises an audio driving circuit 1, a first audio output unit 21, a second audio output unit 22, a first resistance adjusting circuit 3a, a second resistance adjusting circuit 3b and an impedance detecting circuit 4.
At this time, the audio driving circuit 1 includes a first audio output terminal P1a and a second audio output terminal P1 b. The impedance detecting circuit 4 includes a first detecting terminal P41a, a second detecting terminal P41b, a first control output terminal P42a, and a second control output terminal P42 b.
The first audio output terminal P1a of the audio driving circuit 1 is connected to the first audio output unit 21 through the first resistance adjusting circuit 3a for driving the first audio output unit 21 to generate sound.
The second audio output terminal P1b of the audio driving circuit 1 is connected to the second audio output unit 22 through the second resistance adjusting circuit 3b, so as to drive the second audio output unit 22 to emit sound.
In other examples, only one of the first resistance adjustment circuit 3a and the second resistance adjustment circuit 3b may exist. That is, the resistance between the audio output terminal of the audio driving circuit 1 and each audio output unit is adjusted by a resistance adjusting circuit.
In other examples, the audio output terminal of the audio driving circuit 1 is a common audio output terminal, and the audio output terminal simultaneously drives the first audio output unit 21 and the second audio output unit 22.
The first detecting terminal P41a of the impedance detecting circuit 4 is connected to the first audio output terminal P1a and the first audio output unit 21 for detecting the resistance of the circuit between the first audio output terminal P1a and the first audio output unit 21.
The second detection terminal P41b of the impedance detection circuit 4 is connected to the second audio output terminal P1b and the second audio output unit 22 for detecting the resistance of the circuit between the second audio output terminal P1b and the second audio output unit 22.
In other examples, the impedance detecting circuit 4 has only one detecting terminal connected to the first audio output terminal P1a, the second audio output terminal P1b, the first audio output unit 21, and the second audio output unit 22.
Furthermore, the resistance of the circuit between the audio output end of the audio driving circuit and the audio output unit comprises the resistance of the circuit between the audio output end of the audio driving circuit and the audio output unit and the internal resistance of the audio output unit. That is, the resistance of the circuit between the first audio output terminal P1a and the first audio output unit 21 includes the resistance of the circuit between the first audio output terminal P1a and the first audio output unit 21 and the internal resistance of the first audio output unit 21. The resistance of the circuit between the second audio output terminal P1b and the second audio output unit 22 includes the resistance of the circuit between the second audio output terminal P1b and the second audio output unit 22 and the internal resistance of the second audio output unit 22.
At this time, the impedance detection circuit can detect not only the resistance value of the line between the audio output terminal of the audio drive circuit and the audio output unit, but also the internal resistance of each audio output unit. Therefore, the resistance value between the audio output end of the audio driving circuit and each audio output unit can be the same by adjusting each resistance adjusting circuit.
It should be noted that, in an actual circuit, each of the detecting terminals of the impedance detecting circuit 4 may be connected to the positive and negative terminals of the corresponding audio output terminal of the audio driving circuit 1, respectively, for measuring the resistance between the positive and negative terminals and the corresponding audio output unit.
Further, the impedance detection circuit 4 controls the resistance outputs of the first resistance adjustment circuit 3a and the second resistance adjustment circuit 3b, respectively. At this time, the impedance detection circuit 4 may output different signals through one control output terminal, or may output corresponding signals through two control output terminals to control the first resistance adjustment circuit 3a and the second resistance adjustment circuit 3 b.
When the impedance detection circuit 4 includes two control output terminals, the first control output terminal P42a of the impedance detection circuit 4 is connected to the first resistance adjustment circuit 3a for controlling the resistance output of the first resistance adjustment circuit 3 a.
The second control output terminal P42b of the impedance detection circuit 4 is connected to the second resistance adjustment circuit 3b for controlling the resistance output of the second resistance adjustment circuit 3 b.
The impedance detection circuit 4 controls the adjustment of the resistance output of one of the resistance adjustment circuits according to the detected resistance value, so that the resistance value between the first audio output terminal P1a and the first audio output unit 21 is equal to the resistance value between the second audio output terminal P1b and the second audio output unit 22. It should be noted that, in the embodiment of the present invention, the resistance values are not limited to be equal absolutely, and a certain error range may be allowed.
Fig. 3 shows an internal block diagram of the aforementioned impedance detection circuit 4.
The impedance detection circuit 4 includes a controlled switch 4s, a resistance measurement circuit 4t, and a control circuit 4 c.
The controlled switch 4s has a first terminal P4s1 connected to the audio output terminal of the audio driver circuit 1, a second terminal P4s2 connected to the resistance measuring circuit 4t, and a control terminal P4c connected to the control circuit 4 c.
The control circuit 4c is connected to the resistance measuring circuit 4t, and is configured to obtain a resistance measurement result of the resistance measuring circuit 4 t.
The control circuit 4c is also connected to the resistance adjusting circuit 3 to control the resistance output of the circuit adjusting circuit 3.
When it is not necessary to measure the resistance between an audio output terminal of the audio driver circuit 1 and its corresponding audio output unit, the control circuit 4c controls to disconnect the first terminal P4s1 and the second terminal P4s2 of the corresponding controlled switch 4 s; otherwise the control circuit 4c controls to communicate the first terminal P4s1 and the second terminal P4s2 of the corresponding controlled switch 4 s.
The control circuit 4c adjusts the resistance output of the resistance adjusting circuit 3 based on the measurement result of the resistance measuring circuit 4 t.
Optionally, the control circuit 4c is further connected to the audio driving circuit 1 (not shown in fig. 3), and when measuring the resistance between an audio output terminal and a corresponding audio output unit, the control circuit 4c sends a control signal to the audio driving circuit 1, so that after receiving the control signal, the audio driving circuit 1 controls the corresponding audio output terminal to output a high-resistance state or controls the audio output terminal to disconnect from the internal circuit of the audio driving circuit 1, and thus, the resistance measuring circuit 4t only measures the line resistance between the audio output terminal and the audio output unit 2 and the internal resistance of the audio output unit 2.
Fig. 4(a) is a circuit diagram of a portion of the controlled switch 4s and the resistance measuring circuit 4t of fig. 3 corresponding to the first audio output terminal P1a, and fig. 4(b) is a circuit diagram of a portion of the controlled switch 4s and the resistance measuring circuit 4t of fig. 3 corresponding to the second audio output terminal P1 b. The circuits shown in fig. 4(a) and 4(b) together constitute a circuit diagram of an example of the controlled switch 4s and the resistance measuring circuit 4t in fig. 3.
In this circuit, the first audio output terminal P1a is a first positive audio output terminal LP and a first negative audio output terminal LN. The first audio output unit 21 is the left speaker 6. At this time, the first positive audio output LP and the first negative audio output LN are connected through the audio line and drive the left speaker 6.
The second audio output terminal P1b is the second positive audio output terminal RP and the second negative audio output terminal RN. The second audio output unit 22 is the right speaker 7. At this time, the second positive audio output terminal RP and the second negative audio output terminal RN are connected through the audio line and drive the right speaker 7.
The resistance measurement circuit 4t includes a first resistance measurement circuit U1 and a second resistance measurement circuit U2. The first resistance measuring circuit U1 is used to measure the resistance of the circuit between the first positive and negative audio output terminals LP and LN and the first left speaker 6. The second resistance measurement circuit U2 is used to measure the resistance of the circuit between the second positive and negative audio output terminals RP, RN and the right speaker 7.
In this circuit, the controlled switch 4s is a switch SW 1-switch SW8, which is controlled by the control circuit 4c to control the corresponding switch to be in a connected state only when the resistance value between the audio output terminal and the corresponding speaker needs to be measured. All of the controlled switches SW1-SW8 shown in FIG. 4 are in a connected state.
Specifically, when the switch SW1 is in the on state, the first negative audio output LN is grounded; when the switch SW2 is in a connected state, the first positive audio output terminal LP is connected to the power supply VCC through the first resistor R1; thus, the equivalent resistance of the circuit between the R1 and the first positive and negative audio output terminals forms a resistance voltage divider circuit. Switches SW3, SW4 control the connection of the two inputs of the first resistance measurement circuit U1 to the first positive and negative audio output terminals LP, LN.
When the switch SW5 is in the connected state, the second negative audio output terminal RN is grounded; when the switch SW6 is in a connected state, the second positive audio output terminal RP is connected to the power supply VCC through the fifth resistor R5; thus, the equivalent resistance of the circuit between R5 and the second positive and negative audio output terminals forms a resistive divider circuit. The switches SW7, SW8 control the connection of the two input terminals of the second resistance measurement circuit U2 to the second positive and negative audio output terminals RP, RN.
The working principle of the resistance measuring circuit U1 is illustrated by taking the example of measuring the resistance values of the first positive and negative audio output terminals LP and LN and the left speaker 6. The resistance measuring circuit U2 operates in the same manner.
The first resistor R1 is connected in series with the equivalent resistor formed by the first positive and negative audio output terminals LP and LN and the circuit of the left speaker 6 between the power supply VCC and the ground.
The first resistance measurement circuit U1 includes a proportional circuit composed of a second resistor R2, a third resistor R3, a fourth resistor R4, and a first operational amplifier U3, and a voltage analog-to-digital conversion circuit ADC1 connected to the proportional circuit.
One end of the second resistor is connected with one end of the switch SW3, and the other end of the second resistor is connected with the equidirectional input end of the first operational amplifier U3; one end of the third resistor is connected to one end of the switch SW4, and the other end is connected to the inverting input terminal of the first operational amplifier U3. One end of the fourth resistor R4 is connected to the inverting input terminal of the first operational amplifier U3, and the other end is connected to the output terminal of the first operational amplifier U3. The output end of the first operational amplifier U3 is connected to the input end of the voltage analog-to-digital conversion circuit ADC 1.
It should be noted that the proportional circuit is used for proportionally amplifying the measured voltage, and the voltage analog-to-digital conversion circuit is used for measuring the voltage value, which is common knowledge in the art and will not be described in detail herein.
The voltage analog-to-digital conversion circuit ADC1 converts the voltage output from the first operational amplifier U3 into a digital signal and outputs the digital signal to the control circuit 4c (not shown in fig. 4). The voltage value is divided by the ratio of the fourth resistor R4 to the third resistor R3 to obtain the voltage values at the two ends of the first positive and negative audio output terminals LP and LN.
Since the voltage VCC is known, and the voltage values at the two ends of the equivalent resistor formed by the resistance R1 of the first resistor, the first positive and negative audio output terminals LP and LN, and the circuit of the left speaker 6 are also obtained by the above method, the resistance values of the equivalent resistor formed by the first positive and negative audio output terminals LP and LN, and the circuit of the left speaker 6 can be calculated by the resistor voltage dividing formula.
In the above embodiments, the audio driving circuit 1 and the impedance detecting circuit 4 may be independent circuits or chips, or may be integrated in the earphone control chip. The headphone control chip is, for example, a bluetooth chip CSR8670C, and the audio driver circuit 1 and the impedance detection circuit 4 are integrated therein.
The resistance adjustment circuit in each of the above embodiments may be formed of, for example, a MAX5434 chip. The MAX5434 chip can receive external signals to control and adjust the resistance value between two resistor output ends of the MAX chip.
Referring to fig. 5, the audio output balancing circuit is shown, in which the chip CSR8670C has the aforementioned audio driving circuit and the aforementioned impedance detection circuit integrated therein.
The first positive and negative audio output terminals LP, LN of the chip CSR8670C are connected to and drive the left speaker 6, and the second positive and negative audio output terminals RP, RN of the chip CSR8670C are connected to and drive the right speaker 7.
A MAX5434 chip is connected in series on the audio line between the first positive and negative audio output ends LP and LN and the left loudspeaker 6. And a MAX5434 chip is connected in series on the audio line between the second positive and negative audio output ends RP and RN and the right loudspeaker 7.
The resistance values of the actual outputs of the two MAX5434 chips are controlled by the CSR8670C chip. Specifically, the first serial clock output terminal SCL1 and the first serial data output terminal SDA1 of the CSR8640C chip are used to output a control command to the MAX5434 chip connected in series on the audio line between the first positive and negative audio output terminals LP and LN and the left speaker 6, controlling the resistance output between the L port and the W port thereof. The second serial clock output terminal SCL2 and the second serial data output terminal SDA2 of the CSR8640C chip are used to output a control command to the MAX5434 chip connected in series on the audio line between the second positive and negative audio output terminals RP, RN and the right speaker 7, controlling the resistance output between the L port and the W port thereof.
Pin T1 of the CSR8640C chip is connected to the first positive audio output LP and pin T2 is connected to the first negative audio output LN. The pin T3 of the CSR8640C chip is connected to the second positive audio output RP, and the pin T4 is connected to the second negative audio output RN.
When the resistance of the circuit between the first positive and negative audio output ends LP and LN and the left loudspeaker 6 needs to be measured, the CSR8640C chip controls the internal audio driving circuit to output a high-resistance state at the first positive and negative audio output ends LP and LN, the CSR8640C chip controls the pin T1 and the pin T2 to be communicated with the resistance measuring circuit inside the CSR8640C chip, and the resistance measuring circuit detects the resistance of the circuit between the first positive and negative audio output ends LP and LN and the left loudspeaker 6. When the resistance measurement is not needed, the chip control pin T1 and the pin T2 of the CSR8640C are disconnected from the resistance measurement circuit inside the chip of the CSR 8640C.
When the resistance of the circuit between the second positive and negative audio output ends RP and RN and the right speaker 7 needs to be measured, the CSR8640C chip controls the internal audio driving circuit to output a high-resistance state at the second positive and negative audio output ends RP and RN, and the CSR8640C chip controls the pin T3 and the pin T4 to be communicated with the resistance measuring circuit inside the CSR8640C chip, and the resistance measuring circuit detects the resistance of the circuit between the second positive and negative audio output ends RP and RN and the right speaker 7. When the resistance measurement is not needed, the chip control pin T3 and the pin T4 of the CSR8640C are disconnected from the resistance measurement circuit inside the chip of the CSR 8640C.
The control circuit inside the CSR8640C chip adjusts the resistance output of one or two MAX5434 chips according to the detected resistance values of the circuits between the first positive and negative audio output terminals LP and LN and the left speaker 6 and the detected resistance values of the circuits between the second positive and negative audio output terminals RP and RN and the right speaker 7, so that the resistance values of the circuits between the first positive and negative audio output terminals LP and LN and the left speaker 6 are the same as the resistance values of the circuits between the second positive and negative audio output terminals RP and RN and the right speaker 7.
Although some specific embodiments of the present invention have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustrative purposes only and are not intended to limit the scope of the present invention. It will be appreciated by those skilled in the art that modifications may be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.
Claims (10)
1. An audio output balancing circuit, characterized in that,
the device comprises an impedance detection circuit, an audio driving circuit, a resistance adjusting circuit and at least two audio output units; wherein,
the resistance adjusting circuit is connected between the audio output end of the audio driving circuit and the at least two audio output units in series;
the detection end of the impedance detection circuit is connected with the audio output end of the audio drive circuit and the at least two audio output units; the control output end of the impedance detection circuit is connected with the resistance adjusting circuit;
the impedance detection circuit respectively detects the resistance values between the audio output end of the audio driving circuit and at least two audio output units, and controls the resistance output of the resistance adjusting circuit according to the detection result, so that the resistance values of the circuits between the audio output end of the audio driving circuit and each audio output unit are the same.
2. The circuit of claim 1, wherein the resistance adjustment circuit comprises: at least two resistance adjustment circuits; the at least two resistance adjusting circuits are connected with the at least two audio output units in a one-to-one manner;
the control output end of the impedance detection circuit is connected with the resistance adjusting circuit, and the impedance detection circuit comprises:
and the control output end of the impedance detection circuit is connected with the at least two resistance adjusting circuits.
3. The circuit of claim 2, wherein the at least two audio output units comprise: a first audio output unit and a second audio output unit;
the at least two resistance adjustment circuits include: a first resistance adjustment circuit and a second resistance adjustment circuit;
the one-to-one connection of the at least two resistance adjustment circuits with the at least two audio output units includes:
the first resistance adjusting circuit is connected between the audio output end of the audio driving circuit and the first audio output unit in series;
the second resistance adjusting circuit is connected in series between the audio output end of the audio driving circuit and the second audio output unit.
4. The circuit of claim 3, wherein the output of the audio driver circuit comprises: a first audio output terminal and a second audio output terminal;
the first resistance adjustment circuit is connected in series between an audio output terminal of the audio driving circuit and the first audio output unit, and includes:
the first resistance adjusting circuit is connected between a first audio output end of the audio driving circuit and the first audio output unit in series;
the second resistance adjustment circuit is connected in series between the audio output terminal of the audio driving circuit and the second audio output unit, and comprises:
the second resistance adjusting circuit is connected in series between a second audio output end of the audio driving circuit and the second audio output unit.
5. The circuit of claim 3 or 4, wherein the detection terminal of the impedance detection circuit comprises: a first detection end and a second detection end;
the detection end of the impedance detection circuit is connected with the audio output end of the audio drive circuit and the first audio output unit and the second audio output unit, and the impedance detection circuit comprises:
the first detection end of the impedance detection circuit is connected with the audio output end of the audio driving circuit and the first audio output unit, and the second detection end of the impedance detection circuit is connected with the audio output end of the audio driving circuit and the second audio output unit.
6. The circuit according to any one of claims 1-4,
the resistance adjustment circuit includes a digital potentiometer.
7. The circuit of claim 1,
the impedance detection circuit includes: the device comprises a controlled switch, a resistance measuring circuit and a control circuit, wherein the first end of the controlled switch is connected with the audio output end of an audio driving circuit, the second end of the controlled switch is connected with the resistance measuring circuit, and the control end of the controlled switch is connected with the control circuit; the resistance adjusting circuit and the resistance measuring circuit are connected with the control circuit;
the control circuit is configured to control the controlled switch to conduct a circuit between the audio output end of the audio driving circuit and the resistance measuring circuit when the resistance value between the audio output end of the audio driving circuit and the at least two audio output units needs to be detected, and adjust the resistance output of the resistance adjusting circuit according to the measuring result fed back by the resistance measuring circuit.
8. An earphone characterized by comprising the circuit of any one of claims 1-7.
9. The headset of claim 8, further comprising a headset control chip, wherein the impedance detection circuit is integrated into the headset control chip.
10. The headset of claim 8, wherein the resistance adjustment circuit comprises a digital potentiometer comprising a MAX5434 chip.
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| CN201710668000.2A CN107360499B (en) | 2017-08-07 | 2017-08-07 | Audio output balancing circuit and earphone |
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| CN201710668000.2A CN107360499B (en) | 2017-08-07 | 2017-08-07 | Audio output balancing circuit and earphone |
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| CN107360499B CN107360499B (en) | 2023-04-25 |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101521699A (en) * | 2009-03-26 | 2009-09-02 | 中兴通讯股份有限公司 | Mobile phone receiving frequency modulated signal by using built-in aerial and method thereof |
| CN102104388A (en) * | 2009-12-16 | 2011-06-22 | 鸿富锦精密工业（深圳）有限公司 | Audio play system and earphone used by same |
| US20130108080A1 (en) * | 2011-10-31 | 2013-05-02 | Yamaha Corporation | Audio Output Amplifier |
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2017
- 2017-08-07 CN CN201710668000.2A patent/CN107360499B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101521699A (en) * | 2009-03-26 | 2009-09-02 | 中兴通讯股份有限公司 | Mobile phone receiving frequency modulated signal by using built-in aerial and method thereof |
| CN102104388A (en) * | 2009-12-16 | 2011-06-22 | 鸿富锦精密工业（深圳）有限公司 | Audio play system and earphone used by same |
| US20130108080A1 (en) * | 2011-10-31 | 2013-05-02 | Yamaha Corporation | Audio Output Amplifier |
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| CN107360499B (en) | 2023-04-25 |
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