WO2019051815A1

WO2019051815A1 - Control circuit for buzzer, and buzzer

Info

Publication number: WO2019051815A1
Application number: PCT/CN2017/101968
Authority: WO
Inventors: 刘光林; 吴志明; 沈礼胜
Original assignee: 深圳和而泰智能控制股份有限公司
Priority date: 2017-09-15
Filing date: 2017-09-15
Publication date: 2019-03-21
Also published as: CN108780636A

Abstract

A control circuit for a buzzer, and a buzzer. The control circuit comprises: a first input end (11) for a first PWM control signal; a voltage adjustment circuit for adjusting a supply voltage of a buzzer according to an inputted first PWM control signal, the voltage adjustment circuit having a first supply voltage connection end (21) connected to a first port (B1) of the buzzer and a second supply voltage connection end (22) connected to a second port (B2) of the buzzer; a second input end (12) for a second PWM control signal; and an alternating control unit (300) connected to the first supply voltage connection end (21) and the second supply voltage connection end (22), the alternating control unit (300) changing the direction of a current flowing through the buzzer according to a change in the level of the second PWM control signal. The sweet sound effect of the control circuit can be controlled by PWM control signals within a flexible range of adjustment; in addition, positive-negative alternating control is further performed on either end of a buzzer based on the PWM control signals to achieve a better sweet sound effect.

Description

Buzzer control circuit and buzzer

Technical field

The present application relates to the field of signal control technologies, and in particular, to a buzzer control circuit and a buzzer.

Background technique

As a reminder of human-machine communication, the buzzer is a commonly used device that is widely used in various household appliances to provide reminders in human-computer interaction, such as button operation response, function completion reminder, function start reminder, etc. .

In the commonly used buzzer circuit, the buzzer that can be provided has only one frequency, and the sound of the buzzer does not gradually fade out, the sound is relatively stiff, and it sounds unsatisfactory. In some high-end products, based on the user's needs, the buzzer is required to emit a musical sound, or a pleasant hum, thereby deriving the branch of the beautiful buzzer circuit.

There are a variety of methods available to achieve the goal of the American sound buzzer. There is a U.S. buzzer circuit, which introduces a capacitor, so that the voltage of the piezoelectric buzzer is not immediately lost but falls within a certain period of time, thereby forming an effect that the buzzer emits a residual sound and the residual sound volume gradually becomes smaller. Can produce a certain scale, the sound quality is more beautiful.

In the process of implementing the present application, the inventors have found that the related art has the following problems: in the above technical solution for realizing the effect of the sound, it is necessary to select a high-quality discharge electrolytic capacitor, and the capacitance will decrease as the use time elapses, resulting in a discharge time. Variety. Moreover, by means of capacitor discharge, the discharge time is fixed, and the time of the American sound cannot be adjusted.

Summary of the invention

The technical problem to be solved by the embodiment of the present application is to provide a buzzer control circuit and a buzzer, which can solve the problem that the effect of the US sound is poor in the prior art and is affected by the capacitance capacity attenuation.

In order to solve the above technical problems, some embodiments of the present application provide a buzzer control circuit. The control circuit includes: a first input for inputting a first PWM control signal; a first PWM control signal input, a voltage adjustment circuit for adjusting a supply voltage of the buzzer;

The voltage adjustment circuit has a first supply voltage connection end connected to the first port of the buzzer and a second supply voltage connection end connected to the second port of the buzzer;

a second input terminal for inputting a second PWM control signal; an alternate control unit coupled to the first supply voltage connection terminal and the second supply voltage connection terminal; the alternate control unit according to the second PWM control signal The level changes to change the direction of the current flowing through the buzzer.

Optionally, the voltage adjustment circuit includes: at least one operational amplifier; the operational amplifier outputs a corresponding supply voltage of the buzzer at an output thereof according to the first PWM control signal input to the forward input terminal thereof; An output of the operational amplifier is coupled to the first supply voltage connection and the second supply voltage connection.

Optionally, the voltage adjustment circuit includes: the voltage adjustment circuit includes: a thirteenth resistor, a fourteenth resistor, a second capacitor, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, and an operational amplifier; The first input terminal inputting the first PWM control signal is connected to one end of the sixteenth resistor, the other end of the sixteenth resistor is grounded through the thirteenth resistor, and the seventh input resistor is connected to the positive input terminal of the operational amplifier The inverting input of the operational amplifier is grounded through a fourteenth resistor, and is also connected to the output of the operational amplifier through a fifteenth resistor.

Optionally, the voltage adjustment circuit includes: an adjustment unit that outputs a corresponding control current according to the input first PWM control signal, where the control current changes according to a duty ratio change of the first PWM control signal; A signal amplifying unit that controls the current and adjusts the supply voltage of the buzzer.

Optionally, the adjusting unit includes: a switch circuit that is turned on when the first PWM control signal is at a high level, and is turned off when the first PWM control signal is at a low level;

a first resistor coupled to an output of the switching circuit;

And a first capacitor charged by the first resistor when the switch circuit is turned on, wherein a voltage on the first capacitor determines the control current.

Optionally, the control circuit further includes: a DC power supply that provides an operating voltage of the control circuit.

Optionally, the switch circuit includes: a first triode, a second triode, a second resistor, a third resistor, a fourth resistor, a fifth resistor, and a sixth resistor;

The first input terminal is connected to the base of the first triode through a second resistor, and is further connected Passing through a third resistor; the collector of the first transistor is connected to the base of the second transistor through a fifth resistor, and is further connected to the anode of the DC power source through a fourth resistor; The emitter of the pole tube is connected to the anode of the DC power source, and the collector of the second transistor is grounded through a sixth resistor and forms an output of the switching circuit.

Optionally, the switch circuit includes: a sixth triode, a seventh triode, an eighth triode, a second resistor, a third resistor, and a fourth resistor;

a first input terminal inputting the first PWM control signal is connected to a base of the sixth transistor through a second resistor, and is also grounded through a third resistor; a collector of the sixth transistor and a seventh three-pole a base connection of the tube is further connected to the anode of the DC power source through a fourth resistor; a collector of the seventh transistor is connected to an anode of the DC power source, and an emitter of the seventh transistor An emitter of the eighth triode is connected and forms an output end of the switching circuit;

The base of the eighth transistor is also connected to the base of the seventh transistor, and the collector of the eighth transistor is grounded.

Optionally, one end of the first resistor is connected to an output end of the switch circuit, and the other end of the first resistor is grounded through a first capacitor; a connection end of the first capacitor and the first resistor forms the control current Output.

Optionally, the signal amplifying unit includes: a third triode and a seventh resistor;

The base of the third transistor is connected to the output end of the control current, and is also grounded through a seventh resistor; the collector of the third transistor is connected to the anode of the DC power source; The emitter voltage of the triode is the supply voltage of the buzzer.

Optionally, an emitter of the third transistor of the signal amplifying unit is connected to the first supply voltage connection end and the second supply voltage connection end.

Optionally, the alternate control unit includes: a first ground loop that is alternately turned on and off, and a second ground loop;

The first ground loop is connected to the first supply voltage connection end; the second ground loop is connected to the second supply voltage connection end;

When the second PWM control signal is at a high level, the first ground loop is turned on and the second ground loop is turned off, and the supply voltage is applied to the first port of the buzzer;

When the second PWM control signal is low, the first ground loop is turned off and the second The ground loop is turned on and the supply voltage is applied to the second port of the buzzer.

Optionally, the alternate control unit includes: a fourth triode, a fifth triode, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, and a twelfth resistor;

The second input end is connected to one end of the eighth resistor, the other end of the eighth resistor is grounded through a ninth resistor, and is also connected to a base of the fourth triode; the fourth transistor is emitted a pole is grounded, a collector of the fourth triode is connected to a base of the fifth triode through a twelfth resistor, and an emitter of the fifth triode is grounded;

The collector of the fourth transistor is connected to the first supply voltage connection terminal through a tenth resistor, and is also connected to the first port of the buzzer;

The collector of the fifth transistor is connected to the second supply voltage connection through an eleventh resistor, and is also connected to the second port of the buzzer.

In order to solve the above technical problem, another embodiment of the present application provides a buzzer. The buzzer includes: a sounding device, a PWM signal generating device, and a buzzer control circuit as described above; the PWM signal generating device is connected to the buzzer control circuit, and outputs a predetermined PWM control signal to the bee a buzzer control circuit connected to the sounding device to output a corresponding voltage signal to the sounding device.

The control circuit provided in the embodiment of the present application controls the supply voltage of the buzzer through the PWM control signal, thereby realizing a beautiful sound effect such as volume adjustment and volume gradation. The control circuit does not need to use electrolytic capacitors, and the effects of the melody time and the fade or gradation of the volume can be controlled by the PWM control signal, and the adjustment range is flexible. Moreover, the positive and negative alternate control of the buzzer is performed based on the PWM control signal, which can have a better sound effect than the general semi-positive wave control.

DRAWINGS

The one or more embodiments are exemplified by the accompanying drawings in the accompanying drawings, and FIG. The figures in the drawings do not constitute a scale limitation unless otherwise stated.

1 is a functional block diagram of a buzzer control circuit according to an embodiment of the present application;

2 is a functional block diagram of a buzzer control circuit according to another embodiment of the present application;

3 is a circuit schematic diagram of a buzzer control circuit according to an embodiment of the present application;

4 is a circuit schematic diagram of a buzzer control circuit according to another embodiment of the present application;

FIG. 5 is a schematic circuit diagram of a voltage adjustment circuit according to an embodiment of the present application;

FIG. 6 is a schematic circuit diagram of an alternate control unit according to an embodiment of the present application.

Detailed ways

In order to make the objects, technical solutions, and advantages of the present application more comprehensible, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the application and are not intended to be limiting.

The buzzer control circuit of the embodiment of the present application can be applied to various suitable types of buzzers, such as a patch buzzer, a pin buzzer or a piezoelectric buzzer. In an actual application process, the embodiment of the present application may also be used in combination with a PWM signal generating device that provides a PWM (Pulse Width Modulation) control signal. The PWM signal generating means may be any suitable electronic computing device, such as a microcontroller or other device, to provide a specific PWM control signal to the buzzer control circuit of the embodiment of the present application.

The PWM signal generating device can be connected to the buzzer control circuit provided by the embodiment of the present application by a suitable communication method to provide a corresponding PWM control signal. The PWM output device can also function as a built-in function module of the buzzer control circuit, and a PWM control signal is generated to implement control of the buzzer. In some embodiments, additional devices may be additionally added, such as an interaction device that interacts with the user, receives an adjustment command for the PWM control signal, or a suitable wireless communication module, and establishes a communication connection between the different functional units for transmission. Command or control signal or voltage signal. The above equipment can also be reduced according to the actual situation.

The PWM control signal is a pulse waveform with a variable duty cycle and an equal amplitude, and a specific control command can be realized by adjusting a duty ratio in a pulse waveform. PWM control signal is a control method suitable for digital control circuit, suitable for electronic computing equipment to perform soft The program is completely adjusted, such as a personal computer or a computer. In the actual use process, the user can conveniently adjust the PWM control signal through a suitable interactive device to realize the control of the buzzer supply voltage. Compared with the American sound formed by using electrolytic capacitors, the PWM control signal can more flexibly control the sound effect and is not affected by the capacity of the electrolytic capacitor.

In some embodiments, the buzzer control circuit provided in the embodiment of the present application may be integrated into some buzzer, such as a passive buzzer, and the passive buzzer is used as a receiving voltage signal to emit a corresponding sound. Means, and the control circuit provides a voltage signal having a specific waveform thereto according to the input first and/or second PWM control signals. Such a buzzer can conveniently control the input first and/or second PWM control signals through software to control the waveform of the output voltage signal, thereby realizing the effect of the beautiful sound, such as the buzzer volume change, the buzzer sound. The gradual and progressive effect.

FIG. 1 is a functional block diagram of a buzzer control circuit according to an embodiment of the present application. As shown in FIG. 1, the signal input side of the buzzer control circuit is a first input terminal 11 and receives a first PWM control signal. After the received first PWM control signal is processed, a buzzer supply voltage V _supply capable of following the change of the first PWM control signal is outputted on the signal output side of the buzzer control circuit.

As the supply voltage changes, the volume of the buzzer (such as the piezoelectric buzzer) will change accordingly. That is, when the supply voltage is high, a higher volume is emitted. When the supply voltage is low, the volume is reduced.

Inside the buzzer control circuit, an adjustment unit 100 for outputting a control current according to the first PWM control signal and a signal amplifying unit 200 are included.

The adjusting unit 100 may output a corresponding control current according to a change in the duty ratio, that is, a control current that follows a duty cycle change. Of course, the control current outputted in the adjustment unit 100 is a signal having a small amount of change. Therefore, during actual use, the control current cannot be directly output to drive the change in the supply voltage.

The adjusting unit 100 may specifically adopt any suitable function circuit for converting a duty cycle change into a current change, such as a conversion circuit formed by a combination of a switching circuit composed of a plurality of semiconductor devices and other discrete components; or A chip device that is integrally packaged on a substrate, such as a chip that provides corresponding input and output pins.

The signal amplifying unit 200 adjusts the supply voltage according to a change in the control current Amplify the effect of controlling the change in current. The signal amplifying unit 200 can adjust the supply voltage indirectly by the control current, thereby realizing the target of controlling the final supply voltage by the PWM control signal. The signal amplifying unit 200 may specifically adopt any suitable function circuit capable of realizing signal amplification, such as a simple triode, an added bias circuit, an improved triode amplifying circuit, and may be added according to actual conditions. Or delete some discrete components.

Conventionally, buzzers typically have two input ports, one of which is the signal input (ie, the supply voltage is applied) and the other end is grounded. As shown in FIG. 1, the first port B1 and the second port B2 are respectively.

In some embodiments, the output side of the signal amplifying unit 200 may include a first supply voltage connection 21 connected to the first port B1 of the buzzer and a second supply connected to the second port B2 of the buzzer. Voltage connection terminal 22. That is, the supply voltage can be applied to either the first port or the second port; it can be grounded through the first port or grounded through the second port to change the direction of the current flowing through the buzzer. . In the actual application process, the buzzer can be controlled in various suitable ways to make corresponding, variable sounds, such as positive half-wave control to achieve the sound effect; or through the positive between the two ports Negative alternate control, changing the current direction of the buzzer (ie, changing the application port of the supply voltage) to achieve the beautiful sound effect.

FIG. 2 is a functional block diagram of a buzzer control circuit according to another embodiment of the present application. In the present embodiment, an alternate control method based on the PWM control signal is provided. As shown in FIG. 2, in addition to the adjustment unit 100 and the signal amplification unit 200 shown in FIG. 1, the control circuit further includes an alternate control unit 300.

The input side of the alternate control unit 300 is a second input 12 that acquires a second PWM control signal. The output side includes two connection ends respectively connected to the first supply voltage connection end and the second supply voltage connection end to realize control of the buzzer current direction.

The second PWM control signal and the first PWM control signal may be generated and adjusted by the same device, or may be generated or adjusted by two separate devices. Similarly, the second PWM control signal is also a pulse signal of equal amplitude and adjustable pulse width.

The alternate control unit 300 can be based on the high and low level changes of the second PWM control signal The current direction of the buzzer is controlled (ie, the port to which the supply voltage is applied) is controlled. For example, when the second PWM control signal is at a high level, the second port is made a ground port, and current flows from the first port. When the second PWM control signal is low, current flows from the second port, and the first port becomes a ground port. Specifically, the switching function can be implemented using a plurality of suitable functional circuits or a combination thereof, such as a function circuit based on a switching function of the semiconductor device, an action circuit constructed based on an electromagnetic action mechanism, or the like.

The alternating control unit 300 provided by the above embodiment can perform positive and negative alternate control on both ends of the buzzer (ie, change the current direction of the buzzer), and can have better control than the general semi-positive wave control. effect.

In this embodiment, in the process of controlling the sounding of the buzzer, the buzzer can be controlled by inputting a specific second PWM control signal to form a corresponding sound frequency and adjusting the supply voltage by controlling the input first PWM control signal. The volume of the device, the volume can be adjusted to 0, that is, the state of no sound.

FIG. 3 is a schematic circuit diagram of an adjustment unit 100 according to an embodiment of the present application. In this embodiment, a DC power source V1 for providing a control circuit operating voltage may be included. The operating voltage provided by the DC power source can be determined according to the buzzer used, and is related to the maximum supply voltage of the buzzer. The operating voltage provided by the DC power source is V ₁ , and the variable voltage of the supply voltage ranges from 0 to (V ₁ -V _CE ), and V _CE is the voltage drop of the signal amplifying unit.

As shown in FIG. 3, the adjusting unit 100 includes: a first transistor Q1, a second transistor Q2, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a fifth resistor R5. The sixth resistor R6 and the first capacitor C1.

The first transistor Q1, the second transistor Q2, the second resistor R2, the third resistor R3, the fourth resistor R4, the fifth resistor R5, and the sixth resistor R6 constitute a switching circuit 110.

The first input terminal 11 inputting the first PWM control signal is connected to the base of the first transistor Q1 through the second resistor R2, and is also grounded through the third resistor R3. The collector of the first transistor Q1 is connected to the base of the second three-stage tube Q2 through the fifth resistor R5, and is also connected to the anode of the DC power source V1 through the fourth resistor R4. The emitter of the second tertiary tube Q2 is connected to the anode of the DC power source V1, and the collector of the second transistor Q2 is grounded through the sixth resistor R6, and forms an output end of the switch circuit (and The first resistor R1 is connected).

After the switch circuit 110 receives the first PWM control signal, the second transistor Q2 is turned on when the first PWM control signal is at a high level, thereby charging the first capacitor C1 through the first resistor R1.

FIG. 4 is a schematic circuit diagram of an adjustment unit 100 according to another embodiment of the present application. As shown in FIG. 4, the adjusting unit 100 includes a sixth transistor Q6, a seventh transistor Q7, an eighth transistor Q8, a first resistor R1, a second resistor R2, and a third resistor R3. The fourth resistor R4 and the first capacitor C1.

The sixth transistor Q6, the seventh transistor Q7, the eighth transistor Q8, the second resistor R2, the third resistor R3, and the fourth resistor R4 constitute a switching circuit 110.

Input to the first PWM control signal _{PWM. 1} a first input terminal of the second resistor R2 and the sixth base of the transistor Q6 is connected, through a third resistor R3 is grounded through. The collector of the sixth transistor Q6 is connected to the base of the seventh transistor Q7, and is also connected to the anode of the DC power source V1 via the fourth resistor R4. The collector of the seventh transistor Q7 is connected to the anode of the DC power source V1, the emitter of the seventh transistor Q7 is connected to the emitter of the eighth transistor Q8, and the switching circuit is formed. Output (connected to the first resistor R1). The base of the eighth transistor Q8 is also connected to the base of the seventh transistor Q7, and the collector of the eighth transistor Q8 is grounded.

As shown in FIG. 3 and FIG. 4, in the present embodiment, the PNP-type second triode in the switching circuit shown in FIG. 3 is replaced with the NPN-type seventh triode in FIG. The five resistor R5 is replaced by the eighth transistor Q8. After such a change is made, the switching circuit 110 shown in FIG. 4 also implements a function similar to that of FIG. 3 (the output control current is changed by changing the voltage of the first capacitor C1). However, unlike the adjustment unit shown in FIG. 3, in the present embodiment, as the duty ratio of the first PWM control signal increases, the control current will decrease.

The switching circuit 110 shown in FIG. 3 or FIG. 4 can realize the control of the on-time of the switching circuit according to the duty ratio of the PWM control signal, thereby adjusting the voltage on the first capacitor C1. Wherein, the frequency of the first PWM control signal is related to the first capacitor C1, that is, for a specific capacitance capacity, an excessively low PWM frequency may not be able to satisfy normal use. Generally, when the capacitance value of the first capacitor C1 is 100 nf, the frequency of the PWM is greater than 20 KHz, which satisfies the requirement.

In some embodiments, other functional circuits similar to the switching circuit shown in FIG. 3 or FIG. 4 may be employed, including a plurality of switching elements that switch between the on or off states as the level of the PWM control signal changes, such as As shown in Figures 3 and 4, one or more of the semiconductor switching elements are equivalently replaced to change the direction of control. In other embodiments, discrete components or functional circuits may also be added or subtracted, or replaced, depending on the actual situation. The technical solutions for replacing, adjusting or improving the switching circuit by other commonly used triode connection methods or common switching circuit types are well known to those skilled in the art and can be obtained without creative labor.

Referring to FIG. 3 and FIG. 4 , in the embodiment of the present application, an output end of the switch circuit is connected to one end of the first resistor R1 . The other end of the first resistor R1 is grounded through a first capacitor C1; the connection end of the first capacitor C1 and the first resistor R1 forms an output end of the control current I _control .

Wherein, in the embodiment shown in FIG. 3, the second transistor Q2 lengthens the conduction time as the duty ratio of the input first PWM control signal increases. When the second transistor Q2 is turned on, the first capacitor C1 is charged through the first resistor R1; when the second transistor Q2 is turned off, the first capacitor C1 is discharged. Thereby, the magnitude of the control current I _control can be adjusted according to the on-time of the second transistor Q2. In the embodiment shown in FIG. 4, the second transistor Q2 of the PNP type is replaced with the seventh transistor Q7 of the NPN type. The conduction and the cutoff between the seventh transistor Q7 and the second tertiary tube Q2 are reversed.

In some embodiments, the signal amplifying unit 200 is composed of a third transistor Q3 and a seventh resistor R7. The base of the third transistor Q3 is connected to the output terminal of the control current, and is also grounded through the seventh resistor R7. Further, the collector of the third transistor Q3 is connected to the anode of the DC power source V1, and the emitter voltage of the third transistor Q3 is the supply voltage of the buzzer.

As shown in FIGS. 3 and 4, the emitter voltage of the third transistor Q3 (ie, the supply voltage of the buzzer) varies with the current at its base (ie, the control current). Thereby, the supply voltage of the buzzer can be adjusted by the signal amplifying unit by the magnitude of the control current. In particular, other suitable signal amplifying units capable of driving large current/voltage changes with small current/voltage variations can be used. Well known to those skilled in the art Yes, the resistive discrete components in the circuit can be adjusted, added, subtracted, or replaced as needed.

In some embodiments, when the adjustment unit 100 is capable of directly outputting a signal that can be used, as the adjustment unit 100 directly changes according to the duty ratio of the first PWM control signal, the output follows the duty ratio on the output side. The signal amplifying unit 200 can also be reduced by the varying supply voltage. The "voltage adjustment circuit" can be used to indicate that the adjustment unit 100 in the embodiment of the signal amplification unit 200 is reduced to distinguish the adjustment unit 100 in other embodiments.

FIG. 5 is a circuit schematic diagram of a voltage adjustment circuit capable of directly outputting a supply voltage following a duty cycle change according to an embodiment of the present application.

As shown in FIG. 5, the voltage adjustment circuit includes: a thirteenth resistor R51, a fourteenth resistor R52, a second capacitor C51, a fifteenth resistor R53, a sixteenth resistor R54, a seventeenth resistor R55, and an operational amplifier. (ie operational amplifier) U1.

The first input terminal 11 of the first PWM control signal is connected to one end of the sixteenth resistor R54, the other end of the sixteenth resistor R54 is grounded through the thirteenth resistor R51, and the seventeenth resistor R55 and the operational amplifier are also passed. The positive input of U1 is connected. The inverting input terminal of the operational amplifier U1 is grounded through the fourteenth resistor R52, and is also connected to the output end of the operational amplifier U1 through the fifteenth resistor R53. The output end of the operational amplifier U1 forms the signal output side, and the output The supply voltage follows the duty cycle change.

In the embodiment shown in FIG. 5, a circuit structure not including a switching element is employed, and the op amp is directly amplified according to a change in the duty ratio of the first PWM control signal input from the first input terminal 11, at the output. The terminal forms a supply voltage that varies in accordance with a duty cycle change.

The op amp may specifically select a suitable integrated operational amplifier (such as a specific type of integrated operational amplifier chip) or a functional circuit having the same function, which is composed of discrete components. In some embodiments, the op amp can be an integrated op amp.

FIG. 6 is a schematic circuit diagram of an alternate control unit according to an embodiment of the present application. The alternate control unit is respectively connected to the first port B1 and the second port B2 of the buzzer, and changes the current direction of the buzzer according to the level change of the second PWM control signal. That is, change the grounded buzzer port.

As shown in FIG. 6, the alternate control unit 300 includes: a fourth transistor Q4, a fifth three The transistor Q5, the eighth resistor R8, the ninth resistor R9, the tenth resistor R10, the eleventh resistor R11, and the twelfth resistor R12.

The second input terminal 12 is connected to one end of the eighth resistor R8, and inputs a second PWM control signal. The other end of the eighth resistor R8 is grounded through the ninth resistor R9 and also connected to the base of the fourth transistor Q4. The emitter of the fourth transistor Q4 is grounded, and the collector of the fourth transistor Q4 is connected to the base of the fifth transistor Q5 through the twelfth resistor R12, the fifth transistor Q5 The emitter is grounded.

The collector of the fourth transistor Q4 is connected to the first supply voltage connection terminal through a tenth resistor R10, and is also connected to the first port B1 of the buzzer; the collector of the fifth transistor Q5 It is connected to the second supply voltage connection terminal through the eleventh resistor R11, and is also connected to the second port B2 of the buzzer.

In the present embodiment, the ground loops of the first port and the second port of the buzzer are provided by the fourth transistor Q4 and the fifth transistor Q5, respectively. Thereby, the direction of the current changing the buzzer can be changed by controlling the operating states (off/on) of the fourth transistor Q4 and the fifth transistor Q5.

For example, when the second PWM control signal is at a high level, the fourth transistor Q4 is turned on and the fifth transistor Q5 is turned off, the buzzer supply current is passed through the eleventh resistor R11, and the second from the buzzer Port B2 flows into the buzzer and flows out from the first port B1 of the buzzer and through the fourth transistor Q4 to the ground. When the second PWM control signal is low, the fourth transistor Q4 is turned off and the fifth transistor Q5 is turned on, and the buzzer is supplied with current through the tenth resistor R10 from the first port B1 of the buzzer. It flows into the buzzer and flows out from the second port B2 through the fifth transistor Q5 to the ground.

Based on the switching action of the fourth triode Q4 and the fifth triode Q5, when the second PWM control signal is input, the positive and negative alternate control of the buzzer can be realized, and the sound effect is better.

In particular, other suitable switching elements can be used to implement the functions of the alternating control unit 300 described above. That is, the circuit can provide two independent ground loops (such as a first ground loop and a second ground loop) for the first port B1 and the second port B2, respectively, and the two ground loops have corresponding components that function as switches. Such switching-acting components are associated with each other, and one of the grounding loops is turned on while the other grounding loop is closed while operating. And according to the change of the PWM control signal, the on/off condition of the ground loop can be switched. Of course, in some embodiments, it is also possible to use one switching element while controlling the on/off of the two ground loops.

When the buzzer control circuit provided in the above embodiment is applied, various different sound effects can be realized by the following methods. For example, when adjusting the volume, a second PWM control signal corresponding to the desired sound frequency may be input at the second input, and the buzzer may be changed by controlling the duty ratio of the first PWM control signal input at the first input terminal. The volume of the device, or, when it is necessary to form a sound fade-in effect, a second PWM control signal corresponding to the desired sound frequency may be input at the second input terminal, and may be determined according to actual conditions within a certain period of time. Or adjusting), increasing the duty ratio of the first PWM control signal from a minimum linearity to a duty ratio corresponding to the target volume to achieve a sound fade-in effect of the buzzer, or an effect of gradually forming a sound in need of formation At the second input, a second PWM control signal corresponding to the desired sound frequency may be input, and the duty ratio of the first PWM control signal is linearly reduced to 0 to realize the sound of the buzzer within a certain time. Gradually effect.

The above description is only the embodiment of the present application, and thus does not limit the scope of the patent application, and the equivalent structure or equivalent process transformation of the specification and the drawings of the present application, or directly or indirectly applied to other related technologies. The fields are all included in the scope of patent protection of this application.

Claims

A buzzer control circuit, comprising:

a first input for inputting a first PWM control signal;

a voltage adjustment circuit for adjusting a supply voltage of the buzzer according to the input first PWM control signal;

The voltage adjustment circuit has a first supply voltage connection end connected to the first port of the buzzer and a second supply voltage connection end connected to the second port of the buzzer;

a second input for inputting a second PWM control signal;

An alternate control unit coupled to the first supply voltage connection terminal and the second supply voltage connection terminal; the alternate control unit changes a direction of current flowing through the buzzer according to a level change of the second PWM control signal.
The control circuit according to claim 1, wherein said voltage adjustment circuit comprises: at least one operational amplifier;

The operational amplifier outputs a corresponding buzzer supply voltage at its output according to a first PWM control signal input to its forward input terminal;

An output of the operational amplifier is coupled to the first supply voltage connection terminal and the second supply voltage connection terminal.
The control circuit according to claim 2, wherein the voltage adjustment circuit comprises: a thirteenth resistor, a fourteenth resistor, a second capacitor, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, and Operational Amplifier;

a first input terminal inputting the first PWM control signal is connected to one end of the sixteenth resistor, and the other end of the sixteenth resistor is grounded through the thirteenth resistor, and further through the seventeenth resistor and the forward direction of the operational amplifier Input connection

The inverting input of the operational amplifier is grounded through a fourteenth resistor and is also coupled to the output of the operational amplifier via a fifteenth resistor.
The control circuit of claim 1 wherein said voltage adjustment circuit comprises:

Outputting an adjustment unit corresponding to the control current according to the input first PWM control signal, The control current changes in accordance with a duty ratio change of the first PWM control signal; and a signal amplifying unit that adjusts a supply voltage of the buzzer according to the control current.
The control circuit according to claim 4, wherein the adjustment unit comprises:

a switching circuit that is turned on when the first PWM control signal is at a high level, and turned off when the first PWM control signal is at a low level;

a first resistor coupled to an output of the switching circuit;

And a first capacitor charged by the first resistor when the switch circuit is turned on, wherein a voltage on the first capacitor determines the control current.
The control circuit of claim 4 wherein said control circuit further comprises: a DC power supply that provides an operating voltage of the control circuit.
The control circuit according to claim 6, wherein the switching circuit comprises: a first triode, a second triode, a second resistor, a third resistor, a fourth resistor, a fifth resistor, and a sixth resistance;

The first input terminal is connected to the base of the first transistor through a second resistor, and is also grounded through a third resistor; the collector of the first transistor passes through the fifth resistor and the second third The base of the pole tube is connected to the anode of the DC power source through a fourth resistor; the emitter of the second transistor is connected to the anode of the DC power source, and the collector of the second transistor Grounding through a sixth resistor and forming an output of the switching circuit.
The control circuit according to claim 6, wherein the switching circuit comprises: a sixth triode, a seventh triode, an eighth triode, a second resistor, a third resistor, and a fourth resistor;

a first input terminal inputting the first PWM control signal is connected to a base of the sixth transistor through a second resistor, and is also grounded through a third resistor; a collector of the sixth transistor and the seventh a base connection of the triode is further connected to the anode of the DC power source through a fourth resistor; a collector of the seventh transistor is connected to an anode of the DC power source, and an emission of the seventh transistor a pole connected to the emitter of the eighth transistor and forming an output of the switching circuit;

The base of the eighth transistor is also connected to the base of the seventh transistor, and the collector of the eighth transistor is grounded.
The control circuit according to any one of claims 5-8, wherein one end of the first resistor is connected to an output end of the switch circuit, and the other end of the first resistor is grounded through a first capacitor; A connection end of the capacitor and the first resistor forms an output of the control current.
The control circuit according to claim 6, wherein the signal amplifying unit comprises: a third triode and a seventh resistor;

The base of the third transistor is connected to the output end of the control current, and is also grounded through a seventh resistor; the collector of the third transistor is connected to the anode of the DC power source; The emitter voltage of the triode is the supply voltage of the buzzer.
The control circuit according to claim 10, wherein the emitter of the third transistor of the signal amplifying unit is connected to the first supply voltage connection terminal and the second supply voltage connection terminal.
The control circuit according to any one of claims 1-8, wherein the alternate control unit comprises: a first ground loop and a second ground loop that are alternately turned on and off;

The first ground loop is connected to the first supply voltage connection end; the second ground loop is connected to the second supply voltage connection end;

When the second PWM control signal is at a high level, the first ground loop is turned on and the second ground loop is turned off, and the supply voltage is applied to the first port of the buzzer;

When the second PWM control signal is low, the first ground loop is turned off and the second ground loop is turned on, and the supply voltage is applied to the second port of the buzzer.
The control circuit according to any one of claims 1-8, wherein the alternating control unit comprises: a fourth triode, a fifth triode, an eighth resistor, a ninth resistor, a tenth resistor, and a Eleven resistors and twelfth resistors;

The second input end is connected to one end of the eighth resistor, the other end of the eighth resistor is grounded through a ninth resistor, and is also connected to a base of the fourth triode; the fourth transistor is emitted a pole is grounded, a collector of the fourth triode is connected to a base of the fifth triode through a twelfth resistor, and an emitter of the fifth triode is grounded;

The collector of the fourth transistor is connected to the first supply voltage connection terminal through a tenth resistor, and is also connected to the first port of the buzzer;

The collector of the fifth transistor is connected to the second supply voltage connection through an eleventh resistor, and is also connected to the second port of the buzzer.
A buzzer comprising: a sounding device, a PWM signal generating device, and a buzzer control circuit according to any one of claims 1-13;

The PWM signal generating device is connected to the buzzer control circuit, and outputs a predetermined PWM control signal to the buzzer control circuit; the buzzer control circuit is connected to the sounding device to output a corresponding voltage signal To the sounding device.