Buzzer driving system and method thereof

Abstract

The invention relates to a driving system and method of a buzzer, and the driving system of the buzzer is electrically connected with the buzzer and comprises a driving unit, a boosting unit and a multiplying power detection unit, the driving unit comprises a gain control circuit, the gain of an audio signal is adjusted at an amplification factor through the gain control circuit, and a driving voltage is output to the buzzer according to the audio signal; the boosting unit is electrically connected with the driving unit and boosts an input voltage to generate a working voltage to the driving unit; the multiplying power detection unit is electrically connected with the driving unit and the boosting unit, a plurality of hierarchical voltages are generated by default according to the working voltage, and the input voltage is sequentially compared with the hierarchical voltages by the multiplying power detection unit to generate an estimated multiplying power; wherein the amplification factor of the gain control circuit is set corresponding to the estimated factor.

Description

Technical Field

[0001] This application relates to a buzzer driving system and method, and more particularly to a buzzer driving system and method that can detect the boost factor of the operating voltage to adjust the amplification factor of an audio signal. Background Technology

[0002] Buzzers are widely used as sound-generating devices in products such as alarms, multimedia devices, automotive electronic equipment, and toys. They can be mainly divided into piezoelectric and electromagnetic types. When a buzzer is powered on, the internal metal plate vibrates in the resonant cavity to produce sound.

[0003] Current buzzers are mainly driven by digital signals, so most buzzers can only emit a single tone, and sound details are easily filtered out by the buzzer, resulting in poor output sound quality, which is difficult to compare with the output sound quality of a speaker. However, compared with a speaker, buzzers still have irreplaceable advantages such as small size, large volume, low cost and not being easily damaged.

[0004] On the other hand, to make the buzzer sound loud enough, a boost converter needs to be connected to increase the input voltage value, thereby increasing the output voltage value to the buzzer. However, since existing buzzers are driven by digital signals and the equivalent circuit of the buzzer can be regarded as a capacitor, short pulses in the digital signal are easily filtered out, resulting in loss of sound details. Furthermore, if an automatic gain control (AGC) is used to directly control the audio gain, it can also easily lead to signal waveform distortion.

[0005] Therefore, how to solve the existing problems of buzzers is one of the important issues that relevant manufacturers want to address. Summary of the Invention

[0006] In view of this, the purpose of this application is to provide a buzzer driving system and method that can detect the boost ratio of the operating voltage to adjust the amplification ratio of the audio signal, which helps to maintain sound quality while increasing the buzzer volume, allowing the buzzer to display the sound details in the audio signal, and adapting to changes in the input voltage through automatic detection of the boost ratio.

[0007] To achieve the aforementioned objectives, the driving system for the buzzer of this application includes: a driving unit, a boost unit, and a rate detection unit; the driving unit adjusts the gain of an audio signal at a gain ratio through a gain control circuit, and outputs a driving voltage to the buzzer according to the audio signal; the boost unit is electrically connected to the driving unit and boosts an input voltage to generate an operating voltage to the driving unit; the rate detection unit is electrically connected to the driving unit and the boost unit, and by default generates a plurality of level voltages according to the operating voltage, and the rate detection unit compares the input voltage sequentially with each level voltage to generate an estimated rate; wherein, the gain ratio of the gain control circuit is set according to the estimated rate.

[0008] Based on the purpose of this application, this application also provides a method for driving a buzzer, comprising: determining whether an input voltage has been boosted to a working voltage; when it is determined that the input voltage has been boosted to the working voltage, comparing the input voltage sequentially with a plurality of voltage levels to generate an estimated gain; setting an amplification factor according to the estimated gain; adjusting the gain of an audio signal with the amplification factor, and outputting a driving voltage to the buzzer according to the audio signal.

[0009] Compared to previous methods of driving buzzers and increasing their volume, the buzzer driving system and method of this application can generate the driving voltage based on the audio signal in analog or digital form, so that the operation of the buzzer is not limited by the analog or digital signal. Moreover, it can adapt to the high and low changes of the input voltage through automatic detection of the boost ratio, thereby adjusting the amplification ratio of the audio signal. The driving unit adjusts the gain of the audio signal according to the amplification ratio to increase the volume of the buzzer. While increasing the volume, it also prevents the audio signal from being distorted, thereby achieving the purpose of preserving the sound details of the original audio and improving the sound quality. Attached Figure Description

[0010] Figure 1 This is a block diagram illustrating an embodiment of the buzzer driving system of this application.

[0011] Figure 2 This is another block diagram of an embodiment of the buzzer driving system of this application.

[0012] Figure 3 This is a schematic diagram of the gain control circuit in an embodiment of the buzzer driving system of this application.

[0013] Figure 4 This is a schematic diagram of the magnification detection unit in an embodiment of the buzzer driving system of this application.

[0014] Figure 5This is a flowchart of the driving method for the buzzer in this application.

[0015] Figure 6 This is another schematic diagram of the magnification detection unit in an embodiment of the buzzer driving system of this application.

[0016] Symbol explanation:

[0017] 1. Buzzer drive system; 2. Buzzer; 10. Drive unit; 11. Gain control circuit; 111. Amplifier; 12. First stage amplifier; 13. Second stage amplifier; 14, 31. Multiplexer; 20. Boost unit; 30. Ratio detection unit; 32. Comparator; S10~S70 steps; S. Audio signal; D. Drive voltage; M. Ratio signal; R. Preparation signal; VDD. Input voltage; VOUT. Operating voltage; ref. Standard voltage; R, R1, R2, R3, R4, R5, R6. Voltage divider resistors; Rf. Feedback resistor; Rin. Input resistor. Detailed Implementation

[0018] Please refer to Figure 1 As shown, the main objective of this application is to provide a buzzer drive system 1 capable of detecting the boost factor of the operating voltage VOUT and adjusting the amplification factor of the audio signal S accordingly, thereby amplifying the volume of the buzzer 2 while maintaining sound quality. The following detailed description of possible embodiments of this application, with reference to the accompanying drawings, is provided to facilitate understanding by those skilled in the art. However, it should be noted that these details are not intended to limit the scope of the claims made in this application, but are merely for the convenience of those skilled in the art.

[0019] The buzzer drive system 1 of this application is electrically connected to a buzzer 2 and includes a drive unit 10, a boost unit 20 and a rate detection unit 30. The buzzer drive system 1 is a system independent of the buzzer 2 and is set separately from the buzzer 2. Therefore, it can be directly used on the existing buzzer 2 without adjusting the architecture of the buzzer 2.

[0020] The driving unit 10 is electrically connected to the buzzer 2. The driving unit 10 receives an audio signal S corresponding to the buzzer 2 and outputs a driving voltage D to the buzzer 2 according to the audio signal S, causing the buzzer 2 to emit a sound according to the driving voltage D. The audio signal S can be a digital signal or an analog signal from an external device. In one embodiment, the audio signal S can be a digital signal, such as a PWM signal. In another embodiment, the audio signal S can be an analog signal, such as a human voice audio signal, a speech audio signal, or a music audio signal. In one embodiment, the analog signal can include an audio signal generated after processing the human voice audio signal, speech audio signal, or music audio signal into a specific frequency band, wherein the audio signal processing can include weakening or strengthening the intensity of the audio signal in the specific frequency band. In another embodiment, the analog signal can include an audio signal generated after low-pass filtering a digital signal (e.g., a PWM signal). The above description is merely illustrative, and the scope of protection of this application is not limited thereto.

[0021] See further Figure 2 As shown, the driving unit 10 includes a gain control circuit 11, which adjusts the gain of the audio signal S according to a gain factor, and the driving unit 10 outputs the driving voltage D according to the audio signal S adjusted by the gain factor. The gain factor is set according to an estimated gain factor, and the gain control circuit 11 can dynamically adjust the gain factor according to the estimated gain factor.

[0022] The gain control circuit 11 may include an amplifier 111, at least one input resistor Rin, and at least one feedback resistor Rf. Figure 2The gain control circuit 11 described herein includes an input resistor Rin and a feedback resistor Rf as an example, but the number of the at least one input resistor Rin and the at least one feedback resistor Rf is not limited to this embodiment. The input resistor Rin is connected in series to a negative input terminal of the amplifier 111, and the feedback resistor Rf is connected in series between the negative input terminal and an output terminal of the amplifier 111. A positive input terminal of the amplifier 111 receives a standard voltage ref (Voltage Reference). The amplification factor of the gain control circuit 11 corresponds to the resistance ratio of the at least one feedback resistor Rf to the at least one input resistor Rin. In this embodiment, it is the resistance ratio of the feedback resistor Rf to the input resistor Rin. The amplifier 111 adjusts the gain of the audio signal S according to the amplification factor and then outputs the audio signal S from the output terminal. In other words, the gain control circuit 11 can control the amplification factor by adjusting the resistance values ​​of each feedback resistor Rf and each input resistor Rin respectively. Each input resistor Rin and each feedback resistor Rf can be a variable resistor.

[0023] exist Figure 2 In one embodiment, the driving unit 10 further includes a first-stage amplifier 12 and a second-stage amplifier 13. The first-stage amplifier 12 has a first input terminal, a second input terminal, and an output terminal. The first input terminal of the first-stage amplifier 12 is electrically connected to the output terminal of the amplifier 111 to receive the audio signal S after gain adjustment. The second input terminal of the first-stage amplifier 12 is electrically connected to the standard voltage ref, and the output terminal of the first-stage amplifier 12 is electrically connected to a positive terminal of the buzzer 2. After amplifying the audio signal S, the first-stage amplifier 12 outputs a first voltage through its output terminal.

[0024] The second-stage amplifier 13 has a first input terminal, a second input terminal, and an output terminal. The first input terminal of the second-stage amplifier 13 is electrically connected to the output terminal of the first-stage amplifier 12 to receive the first voltage. The second input terminal of the second-stage amplifier 13 is electrically connected to the standard voltage ref, and the output terminal of the second-stage amplifier 13 is electrically connected to the negative terminal of the buzzer 2. After amplifying the first voltage, the second-stage amplifier 13 outputs a second voltage through its output terminal.

[0025] The driving voltage D corresponds to the difference between the first voltage and the second voltage. The driving unit 10 outputs the driving voltage D to the buzzer 2 through the first stage amplifier 12 and the second stage amplifier 13 to drive the buzzer 2 to emit a sound effect corresponding to the driving voltage D.

[0026] The boost unit 20 is electrically connected to an external input power supply and the drive unit 10. The boost unit 20 receives an input voltage VDD provided by the input power supply, boosts the input voltage VDD to generate a working voltage VOUT, and then outputs the working voltage VOUT to the drive unit 10. The working voltage VOUT supplies power to the drive unit 10 to maintain its operation, and can also raise the voltage level of the output stage of the drive unit 10 through the working voltage VOUT. The voltage value of the working voltage VOUT output by the boost unit 20 can be preset to a certain value according to the operating requirements of the drive unit 10 and the buzzer 2, while the voltage value of the input voltage VDD may fluctuate depending on the condition of the input power supply.

[0027] For example, the operating voltage VOUT can be 18V by default, and the input voltage VDD can fall within the range of 2V to 5V. Regardless of how the input voltage VDD fluctuates, the boost unit 20 will boost the input voltage VDD to the default 18V and output it to the drive unit 10 to ensure the stability of the operation of the drive unit 10 and to prevent it from being affected by changes in the input voltage VDD.

[0028] The rate detection unit 30 is electrically connected to the external input power supply, the drive unit 10, and the boost unit 20 to receive the input voltage VDD from the input power supply and the operating voltage VOUT from the boost unit 20. The rate detection unit 30 defaults to having a complex level voltage corresponding to the operating voltage VOUT. The rate detection unit 30 can detect the voltage value of the input voltage VDD, and then generate the estimated rate based on the comparison result between the input voltage VDD and the complex level voltage. Based on the estimated rate, a rate signal M is generated and sent to the driving unit 10 to control the gain control circuit 11 to adjust the amplification rate according to the estimated rate. The rate detection unit 30 controls the gain control unit through the rate signal M to adjust the resistance ratio of the at least one feedback resistor Rf and the at least one input resistor Rin according to the detected rate. Alternatively, after receiving the rate signal M, the gain control unit controls the resistance value change of the at least one feedback resistor Rf and the at least one input resistor Rin according to the detected rate.

[0029] On the other hand, after the boost unit 20 boosts the input voltage VDD to generate the operating voltage VOUT, the boost unit 20 sends a preparation signal R to the rate detection unit 30 so that the rate detection unit 30 can confirm that the boost operation is completed and can perform subsequent boost rate detection.

[0030] See further Figure 3 As shown, in one embodiment, the gain control unit includes a multiplexer 14, a complex feedback resistor Rf, and an input resistor Rin. The multiplexer 14 is connected between the negative input terminal and the output terminal of the amplifier 111. The complex feedback resistors Rf are connected in series between the multiplexer 14 and the input terminal of the amplifier 111. The multiplexer 14 has multiple input terminals, each connected between two series-connected feedback resistors Rf. The gain control unit can adjust the number of complex feedback resistors Rf that are conducting between the negative input terminal and the output terminal of the amplifier 111 through the multiplexer 14, thereby changing the resistance ratio between the conducting complex feedback resistors Rf and the input resistor Rin, and thus adjusting the amplification factor of the amplifier 111.

[0031] Correspondingly, in other embodiments, the gain control unit may also include another multiplexer 14, a complex input resistor Rin, and a feedback resistor Rf. The multiplexer 14 adjusts the number of complex input resistors Rin connected to the negative input terminal of the amplifier 111, thereby changing the resistance ratio between the feedback resistor Rf and the conducting complex input resistor Rin, and thus adjusting the amplification factor of the amplifier 111.

[0032] In addition, in other embodiments, the gain control unit may also include two multiplexers 14, a complex feedback resistor Rf, and a complex input resistor Rin. The two multiplexers 14 adjust the number of complex feedback resistors Rf connected between the negative input terminal and the output terminal of the amplifier 111, and the number of complex input resistors Rin connected to the negative input terminal of the amplifier 111, thereby changing the resistance ratio between the connected complex feedback resistors Rf and the connected complex input resistors Rin to flexibly adjust the amplification factor.

[0033] At Figure 4In this embodiment, the rate detection unit 30 includes a complex voltage divider resistor R, a multiplexer 31, and a comparator 32. The complex voltage divider resistors R are connected in series, with one end connected to the boost unit 20 to receive the operating voltage VOUT, and the other end grounded. Each voltage divider resistor R divides the operating voltage VOUT to generate the complex level voltage. The complex input terminals of the multiplexer 31 are connected to the complex voltage divider resistors R, and each input terminal of the multiplexer 31 is electrically connected between two of the voltage divider resistors R. Therefore, each input terminal of the multiplexer 31 can receive one level voltage through the connected voltage divider resistors R. Layer voltage, in other words, the multiplexer 31 receives the complex layer voltages from the complex input terminals; a positive input terminal of the comparator 32 is connected to an output terminal of the multiplexer 31 to receive each of the layer voltages output by the multiplexer 31, and a negative input terminal of the comparator 32 can be connected to the boost unit 20 to receive the input voltage VDD. The comparator 32 compares each of the layer voltages with the input voltage VDD, and the rate detection unit 30 calculates and generates the estimated rate based on the comparison result of the comparator 32.

[0034] When the comparator 32 compares each of the stage voltages with the input voltage VDD, the rate detection unit 30 uses the comparator 32 to determine one of the stage voltages whose voltage value is not less than the input voltage VDD and whose voltage value is closest to the input voltage VDD, and calculates the estimated rate based on a ratio of the operating voltage VOUT to the stage voltage.

[0035] The buzzer 2 can be a piezoelectric buzzer, whose main structure includes a piezoelectric component, a metal sheet, and a housing. The piezoelectric component can be made of piezoelectric ceramic material. When subjected to voltage, the piezoelectric component deforms due to the piezoelectric effect, which drives the metal sheet to vibrate and produce sound. In addition to covering the piezoelectric component and the metal sheet, the housing also forms a resonant cavity for the piezoelectric component and the metal sheet.

[0036] Compared to a general speaker, the buzzer 2 has the advantages of low power consumption, loud sound, small size, low cost, and not being easily damaged. Moreover, the structure and material characteristics of the buzzer 2 make it highly durable and stable even in extreme environments such as high temperature or humidity. Compared to speakers that are easily damaged and have a high unit price, the buzzer 2 has irreplaceable advantages.

[0037] Please refer to Figure 5As shown, the buzzer driving method of this application is applied to the buzzer 2 and can be executed by the buzzer driving system 1. Steps S10 to S50 can be executed by the magnification detection unit 30, and steps S60 and S70 can be executed by the driving unit 10. The buzzer driving method includes the following steps:

[0038] S10: Determine whether an input voltage VDD has been boosted to a working voltage VOUT. The rate detection unit 30 determines whether the boost unit 20 has completed the boosting operation of the input voltage VDD based on the preparation signal R output by the boost unit 20, and can perform subsequent rate detection based on the working voltage VOUT generated by the boosting operation.

[0039] S20: When it is determined that the input voltage VDD has been boosted to the operating voltage VOUT, one of the multiplexed voltage levels is received, wherein the multiplexer 31 outputs one of the multiplexed voltage levels to the comparator 32.

[0040] S30: Compare the input voltage VDD with the step voltage to determine whether the step voltage is not less than the input voltage VDD, wherein the comparator 32 determines whether the step voltage output by the multiplexer 31 is not less than the input voltage VDD.

[0041] S40: When it is determined that the step voltage is not less than the input voltage VDD, the estimated multiplier is calculated based on the ratio of the working voltage VOUT to the step voltage, and the comparison between the input voltage VDD and the remaining step voltages is stopped.

[0042] S50: When it is determined that the step voltage is less than the input voltage VDD, the next step voltage in the complex step voltage is received, wherein the multiplexer 31 outputs the next step voltage to the comparator 32, and during the execution of step S30 and the repeated execution of step S50, the multiplexer 31 outputs each step voltage in ascending order of the voltage value of the complex step voltage.

[0043] S60: Set a magnification based on the estimated magnification.

[0044] S70: Adjust the gain of an audio signal S according to the amplification factor, and output a driving voltage D to the buzzer 2 according to the audio signal S, wherein a first voltage and a second voltage are first generated according to the audio signal S, and the driving voltage D corresponds to the voltage difference between the first voltage and the second voltage.

[0045] Please refer to Figure 6As shown, taking a 5-bit multiplexer 31 as an example, and the complex voltage divider resistors R consisting of 33 voltage divider resistors R, which generate 32 levels of voltage, the complex voltage divider resistors R include a first voltage divider resistor R1, a second voltage divider resistor R2, a third voltage divider resistor R3, a fourth voltage divider resistor R4, a fifth voltage divider resistor R5, and a sixth voltage divider resistor R6, etc. By setting the resistance values ​​of the complex voltage divider resistors R, the first-level voltage generated between the first voltage divider resistor R1 and the second voltage divider resistor R2 is 0.55 times the operating voltage VOUT, and the voltage value of each subsequent level of voltage differs from the voltage value of the previous level of voltage by 0.015 times the operating voltage VOUT. Therefore, the first-level voltage generated between the second voltage divider resistor R2 and the third voltage divider resistor R3 is 0.535 times the operating voltage VOUT, the first-level voltage generated between the fourth voltage divider resistor R4 and the fifth voltage divider resistor R5 is 0.098 times the operating voltage VOUT, and the first-level voltage generated between the fifth voltage divider resistor R5 and the sixth voltage divider resistor R6 is 0.083 times the operating voltage VOUT. The rest are not elaborated.

[0046] If the operating voltage VOUT is 18V and the input voltage VDD is 2.4V, in step S20, the multiplexer 31 first outputs the lowest voltage level to the comparator 32, that is, the voltage level generated between the fifth voltage divider resistor R5 and the sixth voltage divider resistor R6 is output to the comparator 32; in steps S30 and S50, since the voltage level is 1.494V (0.083 times the operating voltage VOUT), the comparator 32 determines that the voltage level is low. For the input voltage VDD, the multiplexer 31 outputs the next stage voltage to the comparator 32, that is, the stage voltage generated between the fourth voltage divider resistor R and the fifth voltage divider resistor R5 is output to the comparator 32. The next stage voltage is 1.764V (0.098 times the operating voltage VOUT). Similarly, the comparator 32 determines that the stage voltage is less than the input voltage VDD, and then the multiplexer 31 outputs the next stage voltage, and so on.

[0047] When the multiplexer 31 outputs a 2.574V step voltage (0.143 times the operating voltage VOUT) to the comparator 32, the comparator 32 determines that the step voltage is greater than the input voltage VDD, and the rate detection unit 30 calculates the detection rate based on a ratio of the operating voltage VOUT to the step voltage. That is, by using the ratio of 1 times the operating voltage VOUT to 0.143 times the operating voltage VOUT, the detection rate is calculated to be 6.99 times, and the detection rate is close to a true ratio of 7.5 times between the operating voltage VOUT and the input voltage VDD.

[0048] It should be noted that the above content is intended to be illustrative and is not intended to limit the implementation of the complex level voltage and the multiplier detection unit 30.

[0049] In addition, the accuracy of the detection rate corresponding to the true rate is positively correlated with the number of complex stage voltages. The more complex stage voltages there are, the smaller the voltage difference between each stage voltage. When the comparator 32 determines that one stage voltage is greater than the input voltage VDD, the voltage difference between the stage voltage and the input voltage VDD is smaller, and the detection rate calculated by the rate detection unit 30 is more accurate. Therefore, the number of complex stage voltages can be set according to an accuracy requirement. The number of complex stage voltages is positively correlated with the accuracy requirement, and the number of complex stage voltages increases as the accuracy requirement increases. The accuracy requirement represents the accuracy of the detection rate corresponding to the true rate. In the complex stage voltages, the voltage difference between every two consecutive stage voltages can be the same or different, and is not limited to the aforementioned embodiments.

[0050] In summary, the buzzer driving system 1 and method of this application can generate the driving voltage D according to the audio signal S in analog or digital form, so that the operation of the buzzer 2 is not limited by the analog or digital signal, and can benefit from the characteristics of the analog signal, so that the sound emitted by the buzzer 2 is no longer just a single tone, but has more sound effect details, so that the buzzer 2 exhibits sound quality comparable to that of a general loudspeaker, while retaining the advantages of the buzzer 2 such as large volume, low component cost and high durability.

[0051] In addition, the driving system 1 of the buzzer of this application can detect the boost ratio of the boost unit 20 to boost the input voltage VDD to the working voltage VOUT. By automatically detecting the boost ratio, it adapts to the high and low changes of the input voltage VDD and adjusts the amplification ratio of the audio signal S accordingly. The driving unit 10 adjusts the gain of the audio signal S with the amplification ratio, thereby increasing the volume of the buzzer 2 when it emits a sound according to the driving voltage D. At the same time, it prevents the audio signal S from being distorted while increasing the volume, thus achieving the purpose of preserving the sound details of the original audio and improving the sound quality.

[0052] This application discloses preferred embodiments only. Those skilled in the art should understand that the above embodiments are merely for describing this application and are not intended to limit the scope of the claims. Any variations or substitutions equivalent to the above embodiments should be interpreted as falling within the spirit or scope of this application. Therefore, the scope of protection of this application should be based on the scope defined by the claims.

Claims

1. A driving system of a buzzer, electrically connected to a buzzer, comprising: a driving unit, comprising a gain control circuit, the driving unit adjusting a gain of an audio signal by the gain control circuit at an amplification rate, and outputting a driving voltage to the buzzer according to the audio signal; a boosting unit, electrically connected to the driving unit, boosting an input voltage to generate a working voltage to the driving unit; a rate detecting unit, electrically connected to the driving unit and the boosting unit, and generating a plurality of level voltages according to the working voltage by default, the rate detecting unit comparing the input voltage with each of the level voltages in sequence to generate an estimated rate; wherein the amplification rate of the gain control circuit is set according to the estimated rate.

2. The driving system of a buzzer of claim 1, wherein: the rate detecting unit comprises a comparator, a positive input terminal of the comparator receiving each of the level voltages, and a negative input terminal of the comparator receiving the input voltage, and comparing each of the level voltages and the input voltage to generate the estimated rate.

3. The driving system of a buzzer of claim 2, wherein: the rate detecting unit comprises a plurality of voltage dividing resistors and a multiplexer, the plurality of voltage dividing resistors being connected in series, one end of the series of the plurality of voltage dividing resistors receiving the working voltage, and the other end being grounded, each of the plurality of voltage dividing resistors dividing the working voltage to generate the plurality of level voltages; an output terminal of the multiplexer is electrically connected to the positive input terminal of the comparator, a plurality of input terminals of the multiplexer are connected to the plurality of voltage dividing resistors, and each of the input terminals of the multiplexer is electrically connected between two of the voltage dividing resistors; the multiplexer transmits each of the level voltages to the comparator according to one of the level voltages of each of the input terminals.

4. The driving system of a buzzer of claim 3, wherein: the rate detecting unit determines one of the level voltages which is not less than the input voltage and is closest to the input voltage by the comparator, and calculates the estimated rate according to a voltage dividing ratio of the working voltage corresponding to the level voltage.

5. The driving system of a buzzer of claim 4, wherein: the multiplexer outputs each of the level voltages to the comparator in sequence from small to large according to the voltage value, and the rate detecting unit stops voltage comparison when the comparator determines that one of the level voltages is greater than the input voltage.

6. The driving system of a buzzer of claim 1, wherein: the gain control circuit comprises an amplifier, the amplifier being connected to at least one input resistor and at least one feedback resistor, and the gain control circuit adjusts a resistance ratio of the at least one feedback resistor and the at least one input resistor to control the amplification rate according to the estimated rate.

7. A driving method of a buzzer, comprising: determining whether an input voltage has been boosted to a working voltage; ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ When judging that the input voltage has been boosted to the operating voltage, the input voltage is sequentially compared with multiple stage voltages to generate an estimated multiplication factor; An amplification factor is set according to the estimated multiplication factor; The gain of an audio signal is adjusted by the amplification factor, and a driving voltage is output according to the audio signal to the buzzer.

8. The driving method of the buzzer according to claim 7, wherein, The stage voltages are sequentially compared with the input voltage from small to large according to the voltage values of the multiple stage voltages; When judging that one stage voltage is less than the input voltage, the input voltage is sequentially compared with the next stage voltage; When judging that one stage voltage is not less than the input voltage, the comparison of the input voltage with the remaining stage voltages is stopped.

9. The driving method of the buzzer according to claim 7, wherein, When judging that one stage voltage is not less than the input voltage, the estimated multiplication factor is calculated according to a ratio of the operating voltage to the stage voltage.

10. The driving method of the buzzer according to claim 7, wherein, The number of the multiple stage voltages is positively related to a precision requirement, and the number of the multiple stage voltages is increased with the increase of the precision requirement.

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