WO2019085861A1

WO2019085861A1 - Buzzer drive circuit

Info

Publication number: WO2019085861A1
Application number: PCT/CN2018/112432
Authority: WO
Inventors: 王苗; 张久庆
Original assignee: 联合汽车电子有限公司
Priority date: 2017-10-30
Filing date: 2018-10-29
Publication date: 2019-05-09
Also published as: CN107680573B; CN107680573A

Abstract

A buzzer drive circuit, comprising a first pulse circuit (10), a second pulse circuit (20), an energy storage circuit (30), and an output circuit (40). The first pulse circuit (10) is connected to the energy storage circuit (30) and provides a single pulse signal (V1) to the energy storage circuit (30); the energy storage circuit (30) generates a charging/discharging signal (V2) according to the single pulse signal (V1); the energy storage circuit (30) is connected to the output circuit (40) and provides the charging/discharging signal (V2) to the output circuit (40); the second pulse circuit (20) is connected to the output circuit (40) and provides a multi-pulse signal (V3) to the output circuit (40), the frequency of the multi-pulse signal (V3) responding to the vibration frequency of a buzzer (60); the output circuit (40) generates an output signal (V4) according to the charging/discharging signal (V2) and the multi-pulse signal (V3) and provides same to the buzzer (60). The present buzzer drive circuit can improve the tone of a buzzer.

Description

Buzzer drive circuit

Technical field

The present invention relates to the field of driving circuit technologies, and in particular, to a buzzer driving circuit.

Background technique

The buzzer is divided into a DC buzzer and an AC buzzer. As long as the DC buzzer is connected to DC power, it will emit a predetermined sound, such as continuous beeping. This kind of sound cannot be controlled, and the frequency cannot be changed. It is generally used in some simple applications. The AC buzzer is equivalent to a simple speaker. It does not sound when it is connected to the DC. Only when it is connected to the AC, it will emit a corresponding sound according to the frequency of the AC. This buzzer can control the sound output arbitrarily, but the user needs to respond accordingly. The signal is driven. In the electric tailgate system of the car, the buzzer acts as a warning sound and is driven by the tailgate controller. The traditional buzzer drive circuit includes a controller and a switch tube, and the pulse-modulated square wave drive switch tube generated by the controller switches. The switching state causes the voltage across the buzzer to alternately produce a piezoelectric effect, which causes the internal metal piece to vibrate and sound, but the warning sound produced by this circuit is single, the tone is sharp, and the sound quality is poor. Other methods of audio drive include the use of dedicated audio amplifiers and digital-to-analog converters, which provide flexible drive waveforms and sound quality, but at a cost that far exceeds discrete device solutions and is not suitable for applications such as tone. occasion.

Therefore, it is necessary to design a buzzer driving circuit that improves the buzzer sound.

Summary of the invention

It is an object of the present invention to provide a buzzer drive circuit that solves the problem of the existing buzzer chromatic aberration.

In order to solve the above technical problem, the present invention provides a buzzer driving circuit, the buzzer driving circuit comprising a first pulse circuit, a second pulse circuit, a storage circuit and an output circuit, wherein:

The first pulse circuit is connected to the energy storage circuit and provides a single pulse signal to the energy storage circuit;

The energy storage circuit generates a charge and discharge signal according to the single pulse signal, the energy storage circuit is connected to the output circuit, and provides the charge and discharge signal to the output circuit;

The second pulse circuit is connected to the output circuit, and provides a multi-pulse signal to the output circuit, the frequency of the multi-pulse signal is responsive to a vibration frequency of the buzzer;

The output circuit generates an output signal based on the charge and discharge signal and the multi-pulse signal, and supplies the output signal to the buzzer.

Optionally, in the buzzer driving circuit, the buzzer driving circuit further includes an amplitude modulation amplifying circuit, and the amplitude amplifying circuit is connected between the energy storage circuit and the output circuit, The amplitude modulation amplifying circuit includes a first transistor and a second transistor, wherein the first transistor and the second transistor are both NPN transistors, a base of the first transistor is connected to the energy storage circuit, and the first transistor is emitted The pole is connected to the base of the second transistor, the collector of the first transistor is connected to the power source, the emitter of the second transistor is connected to the output circuit, and the collector of the second transistor is connected to the power source.

Optionally, in the buzzer driving circuit, the energy storage circuit includes a first capacitor and a first resistor, and the first capacitor and the first resistor are connected in parallel to form a parallel circuit, where the parallel circuit One end is connected to the first pulse circuit, and the other end is grounded.

Optionally, in the buzzer driving circuit, the output circuit includes a third transistor and a fourth transistor, the third transistor is an NPN transistor, the fourth transistor is a PNP transistor, and the third a base of the transistor and the fourth transistor is connected to the second pulse circuit, an emitter of the third transistor and the fourth transistor is connected to the buzzer, and a collector of the third transistor is connected to the a tank circuit, the collector of the fourth transistor being grounded.

Optionally, in the buzzer driving circuit, the output circuit further includes a second capacitor, the second capacitor is connected to the buzzer at one end, and the third transistor and the The emitter of a four transistor.

Optionally, in the buzzer driving circuit, the first pulse circuit includes a fifth transistor, the fifth transistor is a PNP transistor, and a base of the fifth transistor is connected to a controller, An emitter of the fifth transistor is coupled to the power source, and a collector of the fifth transistor is coupled to the tank circuit.

Optionally, in the buzzer driving circuit, the second pulse circuit includes a sixth transistor, the sixth transistor is an NPN transistor, and a base of the sixth transistor is connected to the controller. The emitter of the sixth transistor is grounded, and the collector of the sixth transistor is connected to the output circuit.

Optionally, in the buzzer driving circuit, the first pulse circuit further includes a seventh transistor, the seventh transistor is an NPN transistor, and a base of the seventh transistor is connected to the controller, The emitter of the seventh transistor is grounded, and the collector of the seventh transistor is connected to the base of the fifth transistor.

Optionally, in the buzzer driving circuit, the buzzer driving circuit further includes a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, and a ninth Resistance and tenth resistor, where:

One end of the third resistor is connected to the energy storage circuit, and the other end is connected to the collector of the fifth transistor;

The fourth resistor is connected to the power source at one end and to the base of the fifth transistor at the other end;

The fifth resistor is connected to the controller at one end and the base of the seventh transistor is connected to the other end;

The sixth resistor is connected to the controller at one end and grounded at the other end;

The seventh resistor is connected to the controller at one end, and the other end is connected to the base of the sixth transistor;

The eighth resistor is connected to the controller at one end and grounded at the other end;

One end of the ninth resistor is connected to the collector of the sixth transistor, and the other end is connected to the base of the third transistor;

One end of the tenth resistor is connected to the collector of the sixth transistor, and the other end is connected to the collector of the third transistor.

Optionally, in the buzzer driving circuit, the duty ratio of the single pulse signal is 10% to 30%.

In the buzzer driving circuit provided by the present invention, a single pulse signal is supplied to the energy storage circuit through the first pulse circuit, and the energy storage circuit filters the single pulse signal to form a charge and discharge signal with a gentle slope, and a charge and discharge signal. The power of the output signal is supplied to the output circuit, and the multi-pulse signal provides an alternating control signal of the output signal to the output circuit. Compared with the conventional driving circuit, only the multi-pulse signal is provided, and the gentle slope of the charging and discharging signal makes the power of the output signal slow. Rising or falling, the buzzer sounds from strong to weak, the tone is moderated, and the buzzer sound is improved.

DRAWINGS

1 is a circuit diagram of a buzzer driving circuit in an embodiment of the present invention;

2 is a circuit diagram of a buzzer driving circuit in another embodiment of the present invention;

3 is a waveform diagram of a signal of a buzzer driving circuit in an embodiment of the present invention;

The figure shows: 10 - first pulse circuit; 20 - second pulse circuit; 30 - energy storage circuit; 40 - output circuit; 50 - amplitude modulation amplifier circuit; 60 - buzzer;

Detailed ways

The buzzer driving circuit proposed by the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Advantages and features of the present invention will be apparent from the description and appended claims. It should be noted that the drawings are in a very simplified form and all use non-precise proportions, and are only for convenience and clarity to assist the purpose of the embodiments of the present invention.

The core idea of the present invention is to provide a buzzer drive circuit for improving the buzzer tone.

In order to achieve the above idea, the embodiment provides a buzzer driving circuit. As shown in FIGS. 1 and 2, the buzzer driving circuit includes a first pulse circuit 10, a second pulse circuit 20, a storage circuit 30, and The output circuit 40, wherein: the first pulse circuit 10 is connected to the energy storage circuit 30, and supplies a single pulse signal V1 to the energy storage circuit 30. As shown in FIG. 3, the waveform of the single pulse signal V1 is a single pulse. a width of 1 millisecond to 5 milliseconds, preferably 2 milliseconds; the storage circuit 30 generates a charge and discharge signal V2 according to the single pulse signal V1, and the energy storage circuit 30 is connected to the output circuit 40, and The output circuit 40 provides the charge and discharge signal V2; the second pulse circuit 20 is connected to the output circuit 40, and provides a multi-pulse signal V3 to the output circuit 40, the frequency of the multi-pulse signal V3 is responsive to the bee The vibration frequency of the horn 60 (i.e., the buzzer 60 emits a sound within a certain oscillating frequency, and the frequency of the multi-pulse signal should be within the range); the output circuit 40 is based on the charge and discharge signal V2 and the plurality Pulse signal V3 produces an output signal V4 and will Said output signal V4 is supplied to the buzzer 60.

Specifically, in the buzzer driving circuit, the buzzer driving circuit further includes an amplitude amplifying circuit 50, and the amplitude amplifying circuit 50 is connected between the energy storage circuit 30 and the output circuit 40. The amplitude modulation amplifying circuit 50 includes a first transistor Q1 and a second transistor Q2. The first transistor Q1 and the second transistor Q2 are both NPN transistors, and the base of the first transistor Q1 is connected to the energy storage. The circuit 30 is specifically connected to a parallel circuit formed by R1 and C1. The emitter of the first transistor Q1 is connected to the base of the second transistor Q2, and the collector of the first transistor Q1 is connected to the power supply VDD. The emitter of the second transistor Q2 is connected to the output circuit 40, specifically connected to the collector of the third transistor Q3, and the collector of the second transistor Q2 is connected to the power supply VDD. The first transistor Q1 and the second transistor Q2 constitute an amplifying circuit that amplifies the amplitude of the charge and discharge signal V2 to provide its driving capability.

Further, in the buzzer driving circuit, the tank circuit 30 includes a first capacitor C1 and a first resistor R1, and the first capacitor C1 and the first resistor R1 are connected in parallel to form a parallel circuit. The parallel circuit can buffer the falling edge of the single pulse signal V1 to form a gentle descending slope, so that the tone of the buzzer is strongly weakened, one end of the parallel circuit is connected to the first pulse circuit 10, and the other end is grounded. In addition, the energy storage circuit 30 may also have a parallel circuit formed by an inductor and a resistor. The parallel circuit is connected to the first pulse circuit 10 at one end and the amplitude modulation amplifier circuit 50 at the other end. The parallel circuit can make the rising edge of the single pulse signal V1. Buffering forms a slower rising edge, making the buzzer's tone stronger and weaker.

In addition, in the buzzer driving circuit, the output circuit 40 includes a third transistor Q3 and a fourth transistor Q4, the third transistor Q3 is an NPN transistor, and the fourth transistor Q4 is a PNP transistor. The bases of the third transistor Q3 and the fourth transistor Q4 are connected to the second pulse circuit 20, and the emitters of the third transistor Q3 and the fourth transistor Q4 are connected to one end of the buzzer 60, buzzing The other end of the device 60 is grounded, and the output signal V4 can flow out from the emitters of the third transistor Q3 and the fourth transistor Q4, and flows into the ground through the buzzer, and the buzzer sounds when passing the buzzer, the first The collector of the three transistor Q3 is coupled to the tank circuit 30, or as shown in FIG. 2, to the emitter of the second transistor Q2 in the amplitude modulation amplifier circuit, the collector of which is grounded. The multi-pulse signal generated by the second pulse circuit is amplified to drive the buzzer. A typical implementation is a push-pull drive structure composed of Q3 and Q4. The frequency of the multi-pulse signal is preferably 1 kHz, and the high-power of the multi-pulse signal In the flat phase, Q4 is turned on, and the output signal outputs a low level, and the voltage is about 0V. In the low-level phase of the multi-pulse signal, Q3 is turned on, and the output charging and discharging signal is amplified by the amplitude modulation amplifying circuit. Under the continuous action of the multi-pulse signal, the output can obtain an amplitude-modulated pulse drive signal with a gradually decreasing amplitude. This signal can directly drive the buzzer to get the sound improvement effect.

In this embodiment, the output circuit 40 further includes a second capacitor C2, the second capacitor C2 is connected to the buzzer 60 at one end, and the other end is connected to the third transistor Q3 and the fourth transistor Q4. The emitter, the inductor-type buzzer that needs to be driven symmetrically, can use the second capacitor C2 to achieve the output of the AC.

Specifically, in the buzzer driving circuit, the first pulse circuit 10 includes a fifth transistor Q5, the fifth transistor Q5 is a PNP transistor, and the base of the fifth transistor Q5 is connected to a controller. 70, or connected to the seventh transistor as shown in FIG. 3, the emitter of the fifth transistor Q5 is connected to the power source VDD, and the collector of the fifth transistor Q5 is connected to the tank circuit 30. The second pulse circuit 20 includes a sixth transistor Q6, the sixth transistor Q6 is an NPN transistor, a base of the sixth transistor Q6 is connected to the controller 70, and an emitter of the sixth transistor Q6 is grounded. The collector of the sixth transistor Q6 is connected to the output circuit 40. The first pulse circuit 10 further includes a seventh transistor Q7, the seventh transistor Q7 is an NPN transistor, a base of the seventh transistor Q7 is connected to the controller 70, and an emitter of the seventh transistor Q7 is grounded. The collector of the seventh transistor Q7 is connected to the base of the fifth transistor Q5.

For the first pulse circuit and the second pulse circuit, respectively, the single pulse signal V1 and the multi-pulse signal V3 are output. Typically, the controller 70 periodically generates a single pulse signal to give a signal to the base of the seventh transistor Q7. The seven transistors are turned on, the base of the fifth transistor is grounded, the fifth transistor is turned on, the power supply VDD charges the storage circuit 30, and the voltage value of the charge and discharge signal V2 can be adjusted by the duration of the single pulse signal V1, thereby adjusting the output. The initial value of the amplitude. In addition, the controller 70 also outputs a multi-pulse signal V3 in real time, and the output of the two pulse signals can be realized by one controller 70, and the control method is simple.

Specifically, the buzzer driving circuit further includes a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, and a tenth resistor. R10, wherein: the third resistor R3 is connected to the energy storage circuit 30 at one end, and the collector of the fifth transistor Q5 is connected to the other end; the third resistor R3 functions to isolate and protect the energy storage circuit from the power supply. The fourth resistor R4 is connected to the power supply VDD at one end and to the base of the fifth transistor Q5 at the other end. The fourth resistor functions to turn on the fifth resistor. The fifth resistor R5 is connected to the controller at one end, and the other end is connected to the base of the seventh transistor; the sixth resistor R6 is connected to the controller at one end and grounded at the other end; the fifth resistor and the sixth resistor are To turn on the seventh transistor and protect the seventh transistor. The seventh resistor R7 is connected to the controller 70 at one end and to the base of the sixth transistor Q6 at the other end; the eighth resistor R8 is connected to the controller 70 at one end and grounded at the other end; the seventh resistor and the The eight resistors function to turn on the sixth transistor Q6 and protect the sixth transistor Q6. One end of the ninth resistor R9 is connected to the collector of the sixth transistor Q6, and the other end is connected to the base of the third transistor Q3; one end of the tenth resistor R10 is connected to the collector of the sixth transistor Q6, and the other One end is connected to the collector of the third transistor Q3. The ninth resistor and the tenth resistor function to buffer the pulse signal outputted by the controller to protect the bases of the third transistor and the fourth transistor.

As shown in FIG. 3, the duty ratio of the single pulse signal V1 is 10% to 30%. In the buzzer driving circuit provided in this embodiment, the energy storage circuit is connected by a first pulse circuit, and a single pulse signal is provided to the energy storage circuit, and the energy storage circuit filters the single pulse signal V1. Forming a slower slope of the charge and discharge signal V2, the charge and discharge signal V2 provides the output circuit with the power of the output signal V4, and the multi-pulse signal V3 provides the output circuit with an alternating control signal of the output signal V4, which has only a comparison with the conventional drive circuit. The multi-pulse signal V3, the gentle slope of the charge and discharge signal V2 causes the power of the output signal V4 to rise slowly, so that the tone of the buzzer is from strong to weak, the tone is moderated, and the buzzer tone is improved.

In this embodiment, an amplitude modulation control structure is provided as a buzzer driving circuit to drive a passive buzzer. When the controller 70 adjusts circuit parameters, the amplitude and frequency of the waveform can be adjusted. Compared with the traditional fixed-amplitude square wave drive signal, the amplitude-adjusted drive waveform is expanded in the frequency domain, which improves the sounding effect of the buzzer and enriches the tone. Compared with the audio driving scheme of high-performance analog-to-digital converter (DAC) and audio power amplifier, the amplitude modulation interface proposed in the paper is realized by discrete components, and the cost is greatly reduced, which is suitable for application scenarios such as a buzzer.

The parameters of the single pulse signal and the multi-pulse signal can be adjusted by the controller software. The initial amplitude of the output signal can be adjusted by adjusting the width of the single pulse signal, and the frequency of the output signal can be adjusted by the frequency of the multi-pulse signal. The adjustment can be implemented on the same hardware structure to adapt the buzzer of different kinds of different frequencies to the whole product application, or to realize different audio effects on the same buzzer, and to reduce the overall product system while improving the system audio effect. Complexity and cost.

In this embodiment, the amplitude modulation mechanism is adopted, and the analysis from the frequency domain is to increase the frequency component, which is equivalent to the effect of the spin, using discrete components and a simple digital control method, thereby avoiding the use of expensive digital-to-analog conversion devices and integrated audio power amplifiers. Circuits reduce the cost of the product. The circuit structure supports the direct-drive mode. Compared with the traditional single-side drive, it has the short-circuit protection function in the interface. The traditional single-side drive mode will damage the amplitude modulation parameters of the circuit drive structure when the external buzzer is short-circuited. The drive frequency can be passed through the controller. The software is adjusted to adapt to different buzzers and application scenarios, and the application is very flexible, which reduces the cost of the entire system in different scenarios.

In addition, the single pulse signal and the multi pulse signal can also be realized by an oscillator of a digital circuit or an analog circuit. The first capacitor used for amplitude modulation control may be a ceramic capacitor, or an electrolytic capacitor, a thin film capacitor or other components having a voltage storage function. Transistors for drive and switching control functions can be implemented using other semiconductor devices of equivalent performance, including but not limited to FETs, device parameters are adjusted to change the specific parameters of the waveform, and for less powerful buzzers, Use a push-pull drive circuit.

In summary, the above embodiment details the different configurations of the buzzer driving circuit. Of course, the present invention includes, but is not limited to, the configurations listed in the above embodiments, and any configuration based on the above embodiments is provided. The contents of the transformation are all within the scope of protection of the present invention. Those skilled in the art can make the same according to the content of the above embodiments.

Claims

A buzzer driving circuit includes a first pulse circuit, a second pulse circuit, a tank circuit and an output circuit, wherein:

The first pulse circuit is connected to the energy storage circuit and provides a single pulse signal to the energy storage circuit;

The energy storage circuit generates a charge and discharge signal according to the single pulse signal, the energy storage circuit is connected to the output circuit, and provides the charge and discharge signal to the output circuit;

The second pulse circuit is connected to the output circuit, and provides a multi-pulse signal to the output circuit, the frequency of the multi-pulse signal is responsive to a vibration frequency of the buzzer;

The output circuit generates an output signal based on the charge and discharge signal and the multi-pulse signal, and supplies the output signal to the buzzer.
A buzzer driving circuit according to claim 1, further comprising an amplitude modulation amplifying circuit connected between said energy storage circuit and said output circuit, said amplitude amplifying circuit comprising a first transistor and a a second transistor, wherein the first transistor and the second transistor are both NPN transistors, a base of the first transistor is connected to the energy storage circuit, and an emitter of the first transistor is connected to a base of the second transistor The collector of the first transistor is connected to a power source, the emitter of the second transistor is connected to the output circuit, and the collector of the second transistor is connected to the power source.
The buzzer driving circuit according to claim 1, wherein said energy storage circuit comprises a first capacitor and a first resistor, said first capacitor and said first resistor being connected in parallel to form a parallel circuit, said parallel One end of the circuit is connected to the first pulse circuit, and the other end is grounded.
The buzzer driving circuit according to claim 2, wherein said output circuit comprises a third transistor and a fourth transistor, said third transistor is an NPN transistor, and said fourth transistor is a PNP transistor, said a base of the third transistor and the fourth transistor is connected to the second pulse circuit, an emitter of the third transistor and the fourth transistor is connected to the buzzer, and a collector connection of the third transistor In the tank circuit, the collector of the fourth transistor is grounded.
The buzzer driving circuit according to claim 4, wherein the output circuit further comprises a second capacitor, the second capacitor is connected to the buzzer at one end, and the third transistor and the other end are connected to the other end. The emitter of the fourth transistor.
The buzzer driving circuit according to claim 4, wherein the first pulse circuit comprises a fifth transistor, the fifth transistor is a PNP transistor, and a base of the fifth transistor is connected to a controller, An emitter of the fifth transistor is coupled to the power source, and a collector of the fifth transistor is coupled to the tank circuit.
The buzzer driving circuit according to claim 6, wherein said second pulse circuit comprises a sixth transistor, said sixth transistor is an NPN transistor, and a base of said sixth transistor is connected to said controller The emitter of the sixth transistor is grounded, and the collector of the sixth transistor is connected to the output circuit.
The buzzer driving circuit according to claim 7, wherein said first pulse circuit further comprises a seventh transistor, said seventh transistor is an NPN transistor, and said base of said seventh transistor is connected to said control The emitter of the seventh transistor is grounded, and the collector of the seventh transistor is connected to the base of the fifth transistor.
The buzzer driving circuit according to claim 8, wherein the buzzer driving circuit further comprises a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, and an eighth resistor. a ninth resistor and a tenth resistor, wherein:

One end of the third resistor is connected to the energy storage circuit, and the other end is connected to the collector of the fifth transistor;

The fourth resistor is connected to the power source at one end and to the base of the fifth transistor at the other end;

The fifth resistor is connected to the controller at one end and the base of the seventh transistor is connected to the other end;

The sixth resistor is connected to the controller at one end and grounded at the other end;

The seventh resistor is connected to the controller at one end, and the other end is connected to the base of the sixth transistor;

The eighth resistor is connected to the controller at one end and grounded at the other end;

One end of the ninth resistor is connected to the collector of the sixth transistor, and the other end is connected to the base of the third transistor;

One end of the tenth resistor is connected to the collector of the sixth transistor, and the other end is connected to the collector of the third transistor.
A buzzer driving circuit according to claim 1, wherein said single pulse signal has a duty ratio of 10% to 30%.