CN214256594U - Audio circuit and circuit board of projector - Google Patents
Audio circuit and circuit board of projector Download PDFInfo
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- CN214256594U CN214256594U CN202120339580.2U CN202120339580U CN214256594U CN 214256594 U CN214256594 U CN 214256594U CN 202120339580 U CN202120339580 U CN 202120339580U CN 214256594 U CN214256594 U CN 214256594U
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Abstract
The application discloses circuit board of audio circuit and projecting apparatus belongs to circuit technical field. The audio circuit comprises a power amplifier input circuit, a power amplifier and a power amplifier output circuit. Therein, the power amplifier has pin P1 and pin P2. The power amplifier input circuit includes an adjustable resistor R1 and an adjustable resistor R2 connected at pin P1. The power amplifier output circuit is connected to pin P2. When the audio circuit works, an audio signal output by the host enters the power amplifier through the power amplifier input circuit. The power amplifier is used for amplifying the power of the audio signal. The power amplifier output circuit is used for outputting the audio signal after power amplification to the loudspeaker. The audio circuit can adjust the amplification factor when the power amplifier amplifies the power of the audio signal by adjusting the resistance values of the adjustable resistor R1 and the adjustable resistor R2, thereby adjusting the output volume of the loudspeaker.
Description
Technical Field
The present disclosure relates to circuit technologies, and particularly to an audio circuit and a circuit board of a projector.
Background
A projector is an optical instrument that projects video onto a screen using optical elements. In the related art, a circuit board in a projector includes an audio circuit. The audio circuit can acquire the audio signal of the host, amplify the power of the audio signal and output the amplified power to the loudspeaker.
However, in the related art, the volume of the output sound of the speaker can be adjusted only by adjusting the power of the audio signal output by the host.
SUMMERY OF THE UTILITY MODEL
The embodiment of the application provides a circuit board of audio circuit and projecting apparatus, through adjustable resistance R1 and adjustable resistance R2, the magnification when power amplifier among the adjustable audio circuit enlargies the power of audio signal to adjust the size of speaker output volume. The technical scheme is as follows:
in a first aspect, an audio circuit is provided, comprising: the power amplifier comprises a power amplifier input circuit, a power amplifier and a power amplifier output circuit, wherein the power amplifier is provided with a pin P1 and a pin P2;
the power amplifier input circuit includes adjustable resistance R1 and adjustable resistance R2, adjustable resistance R1 the first end with adjustable resistance R2's first end all is used for inputting audio signal, adjustable resistance R1's second end with adjustable resistance R2's second end all with pin P1 connects, pin P2 with power amplifier output circuit's input is connected, power amplifier is used for right audio signal's power is enlargied.
In the present application, the audio circuit includes a power amplifier input circuit, a power amplifier, and a power amplifier output circuit. Therein, the power amplifier has pin P1 and pin P2. The power amplifier input circuit includes an adjustable resistor R1 and an adjustable resistor R2 connected at pin P1. The power amplifier output circuit is connected to pin P2. When the audio circuit works, an audio signal output by the host enters the power amplifier through the power amplifier input circuit. The power amplifier is used for amplifying the power of the audio signal. The power amplifier output circuit is used for outputting the audio signal after power amplification to the loudspeaker. The audio circuit can adjust the amplification factor when the power amplifier amplifies the power of the audio signal by adjusting the resistance values of the adjustable resistor R1 and the adjustable resistor R2, thereby adjusting the output volume of the loudspeaker.
Optionally, the power amplifier input circuit further includes: the capacitor C1, the resistor R3, the capacitor C2, the resistor R4 and the resistor R5;
a first plate of the capacitor C1 is connected with a first end of the adjustable resistor R1, and a second plate of the capacitor C1 is connected with a ground line GND;
a first end of the resistor R3 is connected with a first end of the adjustable resistor R1, and a second end of the resistor R3 is connected with the ground GND;
a first pole plate of the capacitor C2 is connected with a first end of the adjustable resistor R2, and a second pole plate of the capacitor C2 is connected with the ground line GND;
a first end of the resistor R4 is connected with a first end of the adjustable resistor R2, and a second end of the resistor R4 is connected with the ground GND;
the first end of the resistor R5 is connected with the second end of the adjustable resistor R2, and the second end of the resistor R5 is connected with the second end of the adjustable resistor R1.
Optionally, the power amplifier input circuit further includes: a capacitance C3;
the first plate of the capacitor C3 is connected with the second end of the adjustable resistor R1, and the second plate of the capacitor C3 is connected with the pin P1.
Optionally, the power amplifier further has a pin P3 and a pin P4, the pin P3 and the pin P4 are used for inputting a control signal, and the control signal is used for controlling the amplification factor of the power of the audio signal by the power amplifier.
Optionally, the audio circuit further comprises: a resistor R6 and a resistor R7;
the first end of the resistor R6 is used for inputting the control signal, and the second end of the resistor R6 is connected with the pin P3;
the first end of the resistor R7 is connected with the pin P3, and the second end of the resistor R7 is connected with the ground GND.
Optionally, the audio circuit further comprises: a resistor R8 and a resistor R9;
the first end of the resistor R8 is used for inputting the control signal, and the second end of the resistor R8 is connected with the pin P4;
the first end of the resistor R9 is connected with the pin P4, and the second end of the resistor R9 is connected with the ground GND.
Optionally, the number of the pins P2 is two, and the power amplifier output circuit includes an inductor L1 and an inductor L2;
a first end of the inductor L1 is connected with one pin P2 of the two pins P2, and a second end of the inductor L1 is used for being connected with a loudspeaker;
the first end of the inductor L2 is connected to the other pin P2 of the two pins P2, and the second end of the inductor L2 is used for connecting to a speaker.
Optionally, the inductor L1 includes at least one of a patch magnetic bead, a ferrite inductor, and a wound inductor;
the inductor L2 comprises at least one of a patch magnetic bead, a ferrite inductor and a wound inductor.
Optionally, the audio circuit further comprises: the circuit comprises a resistor R10, a capacitor C4, a capacitor C5, a resistor R11, a capacitor C6, a capacitor C7, a capacitor C8, a resistor R12 and a resistor R13;
a first terminal of the resistor R10 is connected to a first terminal of the inductor L1;
the first plate of the capacitor C4 is connected with the second end of the resistor R10, and the second plate of the capacitor C4 is connected with the ground GND;
the first polar plate of the capacitor C5 is connected with the ground wire GND;
a first end of the resistor R11 is connected with the second plate of the capacitor C5, and a second end of the resistor R11 is connected with a first end of the inductor L2;
the first plate of the capacitor C6 is connected with the second end of the inductor L1, and the second plate of the capacitor C6 is connected with the second end of the inductor L2;
the first plate of the capacitor C7 is connected with the second end of the inductor L1, and the second plate of the capacitor C7 is connected with the ground line GND;
the first plate of the capacitor C8 is connected with the second plate of the capacitor C7, and the second plate of the capacitor C8 is connected with the second end of the inductor L2;
a first end of the resistor R12 is connected with a second end of the inductor L1, and a second end of the resistor R12 is connected with the ground GND;
the first end of the resistor R13 is connected to the second end of the resistor R12, and the second end of the resistor R13 is connected to the second end of the inductor L2.
In a second aspect, there is provided a circuit board of a projector comprising the audio circuit according to the first aspect.
It is understood that the beneficial effects of the second aspect can be referred to the related description of the first aspect, and are not described herein again.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a first audio circuit provided in an embodiment of the present application;
fig. 2 is a schematic structural diagram of a second audio circuit provided in an embodiment of the present application;
fig. 3 is a schematic structural diagram of a third audio circuit provided in an embodiment of the present application;
fig. 4 is a schematic structural diagram of a fourth audio circuit provided in the embodiment of the present application;
fig. 5 is a schematic structural diagram of a fifth audio circuit provided in the embodiment of the present application.
Wherein, the meanings represented by the reference numerals of the figures are respectively as follows:
10. an audio circuit;
110. a power amplifier input circuit;
120. a power amplifier;
130. a power amplifier output circuit;
20. a loudspeaker.
Detailed Description
To make the objects, technical solutions and advantages of the present application more clear, embodiments of the present application will be described in further detail below with reference to the accompanying drawings.
It should be understood that reference to "a plurality" in this application means two or more. In the description of the present application, "/" means "or" unless otherwise stated, for example, a/B may mean a or B; "and/or" herein is only an association relationship describing an associated object, and means that there may be three relationships, for example, a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, for the convenience of clearly describing the technical solutions of the present application, the terms "first", "second", and the like are used to distinguish the same items or similar items having substantially the same functions and actions. Those skilled in the art will appreciate that the terms "first," "second," etc. do not denote any order or quantity, nor do the terms "first," "second," etc. denote any order or importance.
Before explaining the embodiments of the present application in detail, an application scenario of the embodiments of the present application will be described.
A projector is an optical instrument that projects video onto a screen using optical elements. In the related art, a circuit board within a projector may include an audio circuit. The input end of the audio circuit can be connected with the host computer, and the output end of the audio circuit can be connected with the loudspeaker. When the projector works, the host computer outputs an audio signal to an audio circuit of the projector. The audio circuit may amplify the power of the audio signal and output the power-amplified audio signal to the speaker. The loudspeaker is used for performing electro-acoustic conversion on the audio signal, and the volume of the loudspeaker depends on the power of the audio signal input to the loudspeaker.
In the related art, the power of the audio signal input to the speaker is generally adjusted by adjusting the power of the audio signal output by the host, so as to adjust the volume of the output sound of the speaker.
Therefore, the embodiment of the application provides an audio circuit and a circuit board of a projector, and the adjustable resistor R1 and the adjustable resistor R2 can adjust the amplification factor when a power amplifier in the audio circuit amplifies the power of an audio signal, so as to adjust the volume of the output volume of a loudspeaker.
The audio circuit provided in the embodiments of the present application is explained in detail below. In various embodiments of the present application, the connection between two electrical devices is referred to as an electrical connection. Here, the electrical connection means that two electrical devices are connected by wire or wireless to transmit an electrical signal.
Fig. 1 is a schematic structural diagram of an audio circuit 10 according to an embodiment of the present disclosure. Referring to fig. 1, the audio circuit 10 includes a power amplifier input circuit 110, a power amplifier 120, and a power amplifier output circuit 130.
The power amplifier 120 is an electrical device that can amplify and output power of an input signal to a load appliance (e.g., the speaker 20) under certain conditions, thereby driving the load appliance. In the embodiment of the present application, the audio circuit 10 includes a power amplifier 120. After the host outputs the audio signal to the audio circuit 10, the power amplifier 120 in the audio circuit 10 may amplify the power of the audio signal. The power amplifier 120 has a pin P1 and a pin P2, wherein the pin P1 is the input pin of the power amplifier 120; pin P2 is the output pin of power amplifier 120.
The power amplifier input circuit 110 is connected between the host and the power amplifier 120. The power amplifier input circuit 110 has an input terminal and an output terminal. The input end of the power amplifier input circuit 110 may be connected to the host, so as to obtain the audio signal output by the host. The output terminal of the power amplifier input circuit 110 may be connected to a pin P1 of the power amplifier 120, so that when the host outputs an audio signal, the power amplifier input circuit 110 inputs the audio signal to the power amplifier 120 through a pin P1. In the embodiment of the present application, the power amplifier input circuit 110 includes an adjustable resistor R1 and an adjustable resistor R2. A first terminal of the adjustable resistor R1 and a first terminal of the adjustable resistor R2 are both used for inputting audio signals. In other words, the first terminal of the adjustable resistor R1 and the first terminal of the adjustable resistor R2 together form the input terminal of the power amplifier input circuit 110. The first end of the adjustable resistor R1 is connected with the host computer and can be used for inputting the left channel of the audio signal; a first terminal of the adjustable resistor R2 is connected to the host computer and may be used for the right channel of the input audio signal. The second end of the adjustable resistor R1 and the second end of the adjustable resistor R2 together form the output end of the power amplifier input circuit 110, in other words, the second end of the adjustable resistor R1 and the second end of the adjustable resistor R2 are both connected to the pin P1. By adjusting the resistance values of the adjustable resistor R1 and the adjustable resistor R2, the amplification factor of the power amplifier 120 in amplifying the power of the audio signal can be adjusted.
The power amplifier output circuit 130 is connected between the power amplifier 120 and the speaker 20. The power amplifier output circuit 130 also has an input terminal and an output terminal. The input of the power amplifier circuit may be connected to pin P2 of the power amplifier 120. After the power amplifier 120 amplifies the power of the audio signal, the power-amplified audio signal may be input to the power amplifier output circuit 130 through the pin P2. The output terminal of the power amplifier output circuit 130 may be connected to the speaker 20, so as to output the power-amplified audio signal to the speaker 20. The speaker 20 performs an electroacoustic conversion on the power-amplified audio signal to generate a sound.
In operation of the audio circuit 10, an audio signal output from the host enters the power amplifier 120 through the adjustable resistor R1 and the adjustable resistor R2 from the pin P1. After the power amplifier 120 amplifies the audio signal, the power-amplified audio signal is output from the pin P2 to the power amplifier output circuit 130. The power amplifier output circuit 130 is configured to output the power-amplified audio signal to the speaker 20. By adjusting the resistance values of the adjustable resistor R1 and the adjustable resistor R2, the amplification factor of the power amplifier 120 amplifying the power of the audio signal can be adjusted, so as to adjust the volume of the output sound of the speaker 20. Therefore, when the audio circuit 10 is operated, on one hand, the power of the audio signal input to the speaker 20 can be adjusted by adjusting the power of the audio signal output by the host, so as to adjust the output volume of the speaker 20. On the other hand, the amplification factor of the power amplifier 120 amplifying the power of the audio signal may be adjusted by adjusting the resistances of the adjustable resistor R1 and the adjustable resistor R2, so as to adjust the volume of the output sound of the speaker 20.
Generally, in the audio circuit 10, the power amplifier signal-to-noise ratio of the audio circuit 10 is:
wherein, the SNR is the power amplifier signal-to-noise ratio of the audio circuit 10; vSAn effective value of the output voltage for the audio circuit 10; vnIs the effective value of the noise voltage in the audio circuit 10. From the above formula, it can be seen that when VnWhen the signal is reduced, the power amplifier signal-to-noise ratio of the audio circuit 10 can be effectively improved. For the power amplifier 120, the effective value V of the noise floor voltage is amplified while the power of the audio signal is amplifiedn. Therefore, the amplification factor when the power of the audio signal is amplified by the power amplifier 120 is reduced to some extent, and the effective value V of the noise floor voltage in the audio circuit 10 can be effectively reducednThereby improving the power amplifier signal-to-noise ratio of the audio circuit 10. In the present application, the amplification factor of the power amplifier 120 may be reduced by adjusting the resistances of the adjustable resistor R1 and the adjustable resistor R2. Experiments show that when the power amplifier 120 amplifies the power of the audio signal, the amplification factor is reduced from 70 times to 20 times, and the power amplifier signal-to-noise ratio of the audio circuit 10 is increased from 68dB (decibel) to 71 dB. Therefore, by reducing the amplification factor when the power amplifier 120 amplifies the power of the audio signal, the power amplifier signal-to-noise ratio of the audio circuit 10 can be improved.
In other embodiments, the power amplifier 120 of the audio circuit 10 may further have an iic (inter Integrated circuit) interface. The IIC interface is used for inputting a modification instruction. The modification instruction is for modifying an amplification factor at which the power of the audio signal is amplified by the power amplifier 120. By reducing the amplification factor when the power amplifier 120 amplifies the power of the audio signal, the power amplifier signal-to-noise ratio of the audio circuit 10 can be improved.
Fig. 2 is a schematic structural diagram of another audio circuit 10 according to an embodiment of the present disclosure. Referring to fig. 2, in some embodiments, the power amplifier input circuit 110 includes a capacitor C1, a resistor R3, a capacitor C2, a resistor R4, and a resistor R5 in addition to the adjustable resistor R1 and the adjustable resistor R2.
Specifically, a first terminal of the adjustable resistor R1 is used for connecting with a host to obtain an audio signal. The second terminal of the adjustable resistor R1 is used to connect with pin P1 of the power amplifier 120, so as to input the audio signal to the power amplifier 120. The first terminal of the adjustable resistor R2 is also used for connection with a host to obtain an audio signal. The second terminal of the adjustable resistor R2 is used to connect with pin P1 of the power amplifier 120, so as to input the audio signal to the power amplifier 120.
The capacitor C1 is connected between the first end of the adjustable resistor R1 and the ground GND. In other words, the first plate of the capacitor C1 is connected to the first terminal of the adjustable resistor R1, and the second plate of the capacitor C1 is connected to the ground GND.
The resistor R3 is connected between the first end of the adjustable resistor R1 and the ground GND. In other words, a first end of the resistor R3 is connected to a first end of the adjustable resistor R1, and a second end of the resistor R3 is connected to the ground GND;
the capacitor C2 is connected between the first end of the adjustable resistor R2 and the ground GND. In other words, the first plate of the capacitor C2 is connected to the first terminal of the adjustable resistor R2, and the second plate of the capacitor C2 is connected to the ground GND.
The resistor R4 is connected between the first end of the adjustable resistor R2 and the ground GND. In other words, a first terminal of the resistor R4 is connected to a first terminal of the adjustable resistor R2, and a second terminal of the resistor R4 is connected to the ground GND.
The resistor R5 is connected between the second end of the adjustable resistor R2 and the second end of the adjustable resistor R1. In other words, the first terminal of the resistor R5 is connected to the second terminal of the adjustable resistor R2, and the second terminal of the resistor R5 is connected to the second terminal of the adjustable resistor R1.
Further, as shown in fig. 2, the power amplifier input circuit 110 may further include a capacitor C3.
Specifically, the capacitor C3 is connected between the second terminal of the adjustable resistor R1 and the pin P1. In other words, the first plate of the capacitor C3 is connected to the second terminal of the adjustable resistor R1, and the second plate of the capacitor C3 is connected to the pin P1. Meanwhile, since the second terminal of the resistor R5 is connected to the second terminal of the adjustable resistor R1, the capacitor C3 is also connected between the second terminal of the adjustable resistor R1 and the pin P1. In other words, the first plate of the capacitor C3 is also connected to the second terminal of the adjustable resistor R1.
Fig. 3 is a schematic structural diagram of another audio circuit 10 according to an embodiment of the present disclosure. Referring to fig. 3, in some embodiments, the power amplifier 120 further has a pin P3 and a pin P4. Pin P3 and pin P4 may be used for inputting control signals. The control signal may be a level signal. When the level of the control signal changes, the amplification factor of the power amplifier 120 for amplifying the power of the audio signal also changes.
Specifically, the power amplifier 120 further has a pin P3 and a pin P4, the pin P3 being used for inputting a high level signal or a low level signal, and the pin P4 being also used for inputting a high level signal or a low level signal. When the level signal of at least one of the pins P3 and P4 changes, the amplification factor of the power amplifier 120 for amplifying the power of the audio signal also changes. As known from the above description, reducing the amplification factor when the power amplifier 120 amplifies the power of the audio signal can improve the signal-to-noise ratio of the power amplifier of the audio circuit 10. Therefore, in the embodiment of the present application, the amplification factor of the power amplifier 120 can be reduced through the control signal, so as to improve the power amplifier signal-to-noise ratio of the audio circuit 10.
Further, as shown in fig. 3, the audio circuit 10 of the present application further includes a resistor R6, a resistor R7, a resistor R8, and a resistor R9.
Specifically, a first terminal of the resistor R6 is used for inputting a control signal, and a second terminal of the resistor R6 is connected to the pin P3, so that the control signal is input to the pin P3. The resistor R7 is connected between the pin P3 and the ground GND. In other words, the first terminal of the resistor R7 is connected to the pin P3, and the second terminal of the resistor R7 is connected to the ground GND.
The first terminal of the resistor R8 is used for inputting a control signal, and the second terminal of the resistor R8 is connected to the pin P4, so that the control signal is input to the pin P4. The resistor R9 is connected between the pin P4 and the ground GND. In other words, the first terminal of the resistor R9 is connected to the pin P4, and the second terminal of the resistor R9 is connected to the ground GND.
Fig. 4 is a schematic structural diagram of another audio circuit 10 according to an embodiment of the present disclosure. Referring to fig. 4, in some embodiments, the number of the pins P2 of the power amplifier 120 is two. The power amplifier output circuit 130 comprises an inductor L1 and an inductor L2.
Specifically, the number of the power amplifiers 120P2 is two for forming a loop with the speaker 20. The inductor L1 is connected between one pin P2 of the two pins P2 and the speaker 20. In other words, the first terminal of the inductor L1 is connected to one pin P2 of the two pins P2, and the other terminal of the inductor L1 is used for connection to the speaker 20. In this embodiment, the other end of inductor L1 may be connected to the positive terminal of speaker 20. The inductor L2 is connected between the other pin P2 of the two pins P2 and the speaker 20. In other words, the first terminal of the inductor L2 is connected to the other pin P2 of the two pins P2, and the other terminal of the inductor L2 is used for connection to the speaker 20. In the embodiment of the present application, the other end of the inductor L2 may be connected to the negative electrode of the speaker 20.
Further, the inductor L1 includes at least one of a chip magnetic bead, a ferrite inductor, and a wire wound inductor. The inductor L2 includes at least one of a chip magnetic bead, a ferrite inductor, and a wound inductor.
Specifically, the inductance L1 and the inductance L2 are of different types, and the effective value V of the ground noise voltage in the audio circuit 10 isnAnd also different. Therefore, it is desirable to reduce the effective value V of the noise floor voltagenTo improve the signal-to-noise ratio of the power amplifier of the audio circuit 10, an excellent inductance of the magnetic core is required. When 0805 packaged magnetic patch beads are used for both inductor L1 and inductor L2, effective value V of tested ground noise voltagenAt 31mV (millivolts). When the inductor L1 and the inductor L2 both use ferrite inductors formed integrally, and the inductance of the inductor L1 and the inductance of the inductor L2 both are 10 muH (microHenry), the effective value V of the ground noise voltage is testednIs 20 mV. When the inductor L1 and the inductor L2 both use the wound inductor packaged by CD54, and the inductance of the inductor L1 and the inductance of the inductor L2 both use 10 muH, the effective value of the ground noise voltage is testedVnIs 5 mV. Meanwhile, when the inductor L1 and the inductor L2 both use the wound inductor packaged by the CD54, and the inductance of the inductor L1 and the inductance of the inductor L2 are both 22 muH, the effective value V of the ground noise voltage is testednIs 2 mV. When the inductance L1 and the inductance L2 are changed from the chip magnetic bead packaged by 0805 to the wound inductor packaged by CD54, the effective value V of the output voltage of the audio circuit 10 is setSAt 6V, the signal-to-noise ratio increased from 46dB to 68 dB.
Further, fig. 5 is a schematic structural diagram of another audio circuit 10 provided in the embodiment of the present application. Referring to fig. 5, the audio circuit 10 further includes: the circuit comprises a resistor R10, a capacitor C4, a capacitor C5, a resistor R11, a capacitor C6, a capacitor C7, a capacitor C8, a resistor R12 and a resistor R13.
Specifically, the resistor R10 and the capacitor C4 are connected in series between the first end of the inductor L1 and the ground GND. In other words, a first terminal of the resistor R10 is connected to a first terminal of the inductor L1, a first plate of the capacitor C4 is connected to a second terminal of the resistor R10, and a second plate of the capacitor C4 is connected to the ground GND.
The resistor R11 and the capacitor C5 are connected in series between the first end of the inductor L2 and the ground GND. In other words, the first plate of the capacitor C5 is connected to the ground GND, the first terminal of the resistor R11 is connected to the second plate of the capacitor C5, and the second terminal of the resistor R11 is connected to the first terminal of the inductor L2.
The capacitor C6 is connected between the second terminal of the inductor L1 and the second terminal of the inductor L2. In other words, the first plate of the capacitor C6 is connected to the second terminal of the inductor L1, and the second plate of the capacitor C6 is connected to the second terminal of the inductor L2.
The capacitor C7 is connected between the second terminal of the inductor L1 and the ground GND. In other words, the first plate of the capacitor C7 is connected to the second terminal of the inductor L1, and the second plate of the capacitor C7 is connected to the ground GND.
The capacitor C8 is connected between the second plate of the capacitor C7 and the second terminal of the inductor L2. In other words, the first plate of the capacitor C8 is connected to the second plate of the capacitor C7, and the second plate of the capacitor C8 is connected to the second terminal of the inductor L2.
The resistor R12 is connected between the second end of the inductor L1 and the ground GND. In other words, the first terminal of the resistor R12 is connected to the second terminal of the inductor L1, and the second terminal of the resistor R12 is connected to the ground GND.
The resistor R13 is connected between the second terminal of the resistor R12 and the second terminal of the inductor L2. In other words, the first terminal of the resistor R13 is connected to the second terminal of the resistor R12, and the second terminal of the resistor R13 is connected to the second terminal of the inductor L2.
In the present application, the audio circuit 10 includes a power amplifier input circuit 110, a power amplifier 120, and a power amplifier output circuit 130. The power amplifier 120 has a pin P1 and a pin P2. The power amplifier input circuit 110 includes an adjustable resistor R1 and an adjustable resistor R2 connected at pin P1. The power amplifier output circuit 130 is connected to pin P2. When the audio circuit 10 is in operation, the audio signal output by the host enters the power amplifier 120 through the power amplifier input circuit 110. The power amplifier 120 is used to amplify the power of the audio signal. The power amplifier output circuit 130 is configured to output the power-amplified audio signal to the speaker 20. The audio circuit 10 can adjust the amplification factor when the power amplifier 120 amplifies the power of the audio signal by adjusting the resistance values of the adjustable resistor R1 and the adjustable resistor R2, thereby adjusting the output volume of the speaker 20. The power amplifier 120 in the audio circuit 10 may also input modification commands through the IIC interface. The modification instruction is used to modify the amplification factor of the power amplifier 120 for amplifying the power of the audio signal, thereby adjusting the volume of the output of the speaker 20. By reducing the amplification factor of the amplifier in amplifying the power of the audio signal, the power amplifier signal-to-noise ratio of the audio circuit 10 can be improved. Meanwhile, the audio circuit 10 can also use the excellent inductance of the magnetic core to improve the power amplifier signal-to-noise ratio of the audio circuit 10.
The embodiment of the application also provides a circuit board of the projector. The circuit board of the projector includes the audio circuit 10 as in any of the embodiments described above.
Specifically, the audio circuit 10 includes a power amplifier input circuit 110, a power amplifier 120, and a power amplifier output circuit 130. The power amplifier 120 has pin P1 and pin P2. The power amplifier input circuit 110 comprises an adjustable resistor R1 and an adjustable resistor R2. A first terminal of the adjustable resistor R1 and a first terminal of the adjustable resistor R2 are both used for inputting audio signals. The second terminal of the adjustable resistor R1 and the second terminal of the adjustable resistor R2 are both connected to pin P1. Pin P2 is connected to the input of the power amplifier output circuit 130. The power amplifier 120 is used to amplify the power of the audio signal.
In some embodiments, the power amplifier input circuit 110 further comprises: the circuit comprises a capacitor C1, a resistor R3, a capacitor C2, a resistor R4 and a resistor R5. The first plate of the capacitor C1 is connected with the first end of the adjustable resistor R1, and the second plate of the capacitor C1 is connected with the ground GND. A first terminal of the resistor R3 is connected to a first terminal of the adjustable resistor R1, and a second terminal of the resistor R3 is connected to the ground GND. The first plate of the capacitor C2 is connected with the first end of the adjustable resistor R2, and the second plate of the capacitor C2 is connected with the ground GND. A first terminal of the resistor R4 is connected to a first terminal of the adjustable resistor R2, and a second terminal of the resistor R4 is connected to the ground GND. The first end of the resistor R5 is connected with the second end of the adjustable resistor R2, and the second end of the resistor R5 is connected with the second end of the adjustable resistor R1.
In some embodiments, the power amplifier input circuit 110 further comprises: a capacitor C3. The first plate of the capacitor C3 is connected to the second terminal of the adjustable resistor R1, and the second plate of the capacitor C3 is connected to the pin P1.
In some embodiments, the power amplifier 120 further has a pin P3 and a pin P4, the pin P3 and the pin P4 are used for inputting a control signal, and the control signal is used for controlling the amplification factor of the power of the audio signal by the power amplifier 120.
In some embodiments, the audio circuit 10 further comprises: resistor R6 and resistor R7. The first end of the resistor R6 is used for inputting control signals, and the second end of the resistor R6 is connected with the pin P3. A first terminal of the resistor R7 is connected to the pin P3, and a second terminal of the resistor R7 is connected to the ground GND.
In some embodiments, the audio circuit 10 further comprises: resistor R8 and resistor R9. The first end of the resistor R8 is used for inputting control signals, and the second end of the resistor R8 is connected with the pin P4. A first terminal of the resistor R9 is connected to the pin P4, and a second terminal of the resistor R9 is connected to the ground GND.
In some embodiments, the number of the pins P2 is two, and the power amplifier output circuit 130 includes an inductor L1 and an inductor L2. A first terminal of the inductor L1 is connected to one pin P2 of the two pins P2, and a second terminal of the inductor L1 is used for connection to the speaker 20. A first terminal of the inductor L2 is connected to the other pin P2 of the two pins P2, and a second terminal of the inductor L2 is used for connection to the speaker 20.
In some embodiments, the inductor L1 includes at least one of a patch bead, a ferrite inductor, a wound inductor. The inductor L2 includes at least one of a chip magnetic bead, a ferrite inductor, and a wound inductor.
In some embodiments, the audio circuit 10 further comprises: the circuit comprises a resistor R10, a capacitor C4, a capacitor C5, a resistor R11, a capacitor C6, a capacitor C7, a capacitor C8, a resistor R12 and a resistor R13. A first terminal of the resistor R10 is connected to a first terminal of the inductor L1. The first plate of the capacitor C4 is connected with the second end of the resistor R10, and the second plate of the capacitor C4 is connected with the ground GND. The first plate of the capacitor C5 is connected to ground GND. A first terminal of the resistor R11 is connected to the second plate of the capacitor C5, and a second terminal of the resistor R11 is connected to a first terminal of the inductor L2. The first plate of the capacitor C6 is connected to the second terminal of the inductor L1, and the second plate of the capacitor C6 is connected to the second terminal of the inductor L2. The first plate of the capacitor C7 is connected to the second terminal of the inductor L1, and the second plate of the capacitor C7 is connected to the ground GND. The first plate of the capacitor C8 is connected to the second plate of the capacitor C7, and the second plate of the capacitor C8 is connected to the second terminal of the inductor L2. A first terminal of the resistor R12 is connected to the second terminal of the inductor L1, and a second terminal of the resistor R12 is connected to the ground GND. A first terminal of the resistor R13 is connected to the second terminal of the resistor R12, and a second terminal of the resistor R13 is connected to the second terminal of the inductor L2.
In the present application, the audio circuit 10 includes a power amplifier input circuit 110, a power amplifier 120, and a power amplifier output circuit 130. The power amplifier 120 has a pin P1 and a pin P2. The power amplifier input circuit 110 includes an adjustable resistor R1 and an adjustable resistor R2 connected at pin P1. The power amplifier output circuit 130 is connected to pin P2. When the audio circuit 10 is in operation, the audio signal output by the host enters the power amplifier 120 through the power amplifier input circuit 110. The power amplifier 120 is used to amplify the power of the audio signal. The power amplifier output circuit 130 is configured to output the power-amplified audio signal to the speaker 20. The audio circuit 10 can adjust the amplification factor when the power amplifier 120 amplifies the power of the audio signal by adjusting the resistance values of the adjustable resistor R1 and the adjustable resistor R2, thereby adjusting the output volume of the speaker 20. The power amplifier 120 in the audio circuit 10 may also input modification commands through the IIC interface. The modification instruction is used to modify the amplification factor of the power amplifier 120 for amplifying the power of the audio signal, thereby adjusting the volume of the output of the speaker 20. By reducing the amplification factor of the amplifier in amplifying the power of the audio signal, the power amplifier signal-to-noise ratio of the audio circuit 10 can be improved. Meanwhile, the audio circuit 10 can also use the excellent inductance of the magnetic core to improve the power amplifier signal-to-noise ratio of the audio circuit 10.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present application and are intended to be included within the scope of the present application.
Claims (10)
1. An audio circuit, comprising: the power amplifier comprises a power amplifier input circuit, a power amplifier and a power amplifier output circuit, wherein the power amplifier is provided with a pin P1 and a pin P2;
the power amplifier input circuit includes adjustable resistance R1 and adjustable resistance R2, adjustable resistance R1 the first end with adjustable resistance R2's first end all is used for inputting audio signal, adjustable resistance R1's second end with adjustable resistance R2's second end all with pin P1 connects, pin P2 with power amplifier output circuit's input is connected, power amplifier is used for right audio signal's power is enlargied.
2. The audio circuit of claim 1, wherein the power amplifier input circuit further comprises: the capacitor C1, the resistor R3, the capacitor C2, the resistor R4 and the resistor R5;
a first plate of the capacitor C1 is connected with a first end of the adjustable resistor R1, and a second plate of the capacitor C1 is connected with a ground line GND;
a first end of the resistor R3 is connected with a first end of the adjustable resistor R1, and a second end of the resistor R3 is connected with the ground GND;
a first pole plate of the capacitor C2 is connected with a first end of the adjustable resistor R2, and a second pole plate of the capacitor C2 is connected with the ground line GND;
a first end of the resistor R4 is connected with a first end of the adjustable resistor R2, and a second end of the resistor R4 is connected with the ground GND;
the first end of the resistor R5 is connected with the second end of the adjustable resistor R2, and the second end of the resistor R5 is connected with the second end of the adjustable resistor R1.
3. The audio circuit of claim 2, wherein the power amplifier input circuit further comprises: a capacitance C3;
the first plate of the capacitor C3 is connected with the second end of the adjustable resistor R1, and the second plate of the capacitor C3 is connected with the pin P1.
4. The audio circuit of claim 1, wherein the power amplifier further has a pin P3 and a pin P4, the pin P3 and the pin P4 being for inputting a control signal for controlling amplification of the power of the audio signal by the power amplifier.
5. The audio circuit of claim 4, further comprising: a resistor R6 and a resistor R7;
the first end of the resistor R6 is used for inputting the control signal, and the second end of the resistor R6 is connected with the pin P3;
the first end of the resistor R7 is connected with the pin P3, and the second end of the resistor R7 is connected with the ground GND.
6. The audio circuit of claim 4, further comprising: a resistor R8 and a resistor R9;
the first end of the resistor R8 is used for inputting the control signal, and the second end of the resistor R8 is connected with the pin P4;
the first end of the resistor R9 is connected with the pin P4, and the second end of the resistor R9 is connected with the ground GND.
7. The audio circuit according to claim 1, wherein the number of the pins P2 is two, the power amplifier output circuit comprises an inductor L1 and an inductor L2;
a first end of the inductor L1 is connected with one pin P2 of the two pins P2, and a second end of the inductor L1 is used for being connected with a loudspeaker;
the first end of the inductor L2 is connected to the other pin P2 of the two pins P2, and the second end of the inductor L2 is used for connecting to a speaker.
8. The audio circuit of claim 7, wherein the inductance L1 comprises at least one of a patch bead, a ferrite inductor, a wound inductor;
the inductor L2 comprises at least one of a patch magnetic bead, a ferrite inductor and a wound inductor.
9. The audio circuit of claim 7, further comprising: the circuit comprises a resistor R10, a capacitor C4, a capacitor C5, a resistor R11, a capacitor C6, a capacitor C7, a capacitor C8, a resistor R12 and a resistor R13;
a first terminal of the resistor R10 is connected to a first terminal of the inductor L1;
the first plate of the capacitor C4 is connected with the second end of the resistor R10, and the second plate of the capacitor C4 is connected with the ground GND;
the first polar plate of the capacitor C5 is connected with the ground wire GND;
a first end of the resistor R11 is connected with the second plate of the capacitor C5, and a second end of the resistor R11 is connected with a first end of the inductor L2;
the first plate of the capacitor C6 is connected with the second end of the inductor L1, and the second plate of the capacitor C6 is connected with the second end of the inductor L2;
the first plate of the capacitor C7 is connected with the second end of the inductor L1, and the second plate of the capacitor C7 is connected with the ground line GND;
the first plate of the capacitor C8 is connected with the second plate of the capacitor C7, and the second plate of the capacitor C8 is connected with the second end of the inductor L2;
a first end of the resistor R12 is connected with a second end of the inductor L1, and a second end of the resistor R12 is connected with the ground GND;
the first end of the resistor R13 is connected to the second end of the resistor R12, and the second end of the resistor R13 is connected to the second end of the inductor L2.
10. A circuit board for a projector, characterized by comprising the audio circuit according to any one of claims 1 to 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120339580.2U CN214256594U (en) | 2021-02-05 | 2021-02-05 | Audio circuit and circuit board of projector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202120339580.2U CN214256594U (en) | 2021-02-05 | 2021-02-05 | Audio circuit and circuit board of projector |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN214256594U true CN214256594U (en) | 2021-09-21 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202120339580.2U Active CN214256594U (en) | 2021-02-05 | 2021-02-05 | Audio circuit and circuit board of projector |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN214256594U (en) |
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2021
- 2021-02-05 CN CN202120339580.2U patent/CN214256594U/en active Active
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