CN210864979U

CN210864979U - Automobile instrument alarm sound driving device

Info

Publication number: CN210864979U
Application number: CN201921820631.2U
Authority: CN
Inventors: 夏礼智
Original assignee: Yanfeng Visteon Electronic Technology Shanghai Co Ltd
Current assignee: Yanfeng Visteon Electronic Technology Shanghai Co Ltd
Priority date: 2019-10-28
Filing date: 2019-10-28
Publication date: 2020-06-26
Anticipated expiration: 2029-10-28

Abstract

The utility model provides an automobile instrument alarm sound drive arrangement, be equipped with the output interface of the pulse width modulation PWM signal of representing the volume and the MCU microcontroller of the output interface of the PWM signal of representing the tone, volume low pass filter, tone amplitude modulator, tone low pass filter, sound power amplifier, the speaker connects gradually, the last output interface connection volume low pass filter input of the pulse width modulation PWM signal of representing the volume of MCU microcontroller, the last output interface connection tone low pass filter input of the PWM signal of representing the tone of MCU microcontroller. The utility model provides a device has overcome prior art's not enough, and the volume and the tone of alarm sound are controlled respectively by two way pulse width modulation PWM signals, separate the tone and the volume of sound and come independent control, can realize high-quality sound, do not increase MCU's cost again.

Description

Automobile instrument alarm sound driving device

Technical Field

The utility model relates to an electron device especially relates to a high sound quality, can be through the motormeter alarm sound drive arrangement of tone and volume of adjusting output alarm sound.

Background

In the use process of the automobile, an alarm sound is often generated to inform a driver, for example, the alarm sound is not fastened to a safety belt. For safety reasons, these warning sounds are generally implemented by the drive circuit of the instrument cluster. In recent years, users have increasingly high requirements on sound quality, such as adjustable sound level, vivid tone and no noise, so that the circuit design must be continuously improved to meet the continuously improved design requirements.

At present, the following alarm sound driving circuits are commonly used:

(1) the microcontroller MCU outputs a Pulse Width Modulation (PWM) signal, the frequency of the PWM signal corresponds to the tone of sound, and the pulse width of the PWM corresponds to the loudness of the sound. The PWM signal is directly output to a coil of the loudspeaker through a switch triode to send out an alarm sound. The circuit is simplest, but the sound of the loudspeaker is not real enough due to the fact that the PWM signal carries high-order harmonics; in addition, the square wave signal directly drives the speaker, and also causes damage to the speaker.

(2) A digital-to-analog conversion DAC and power amplification integrated circuit driving circuit is adopted, and an MCU outputs an I2S port through special sound to convert the sound into an analog signal for the DAC, and then the analog signal is amplified through power to drive a loudspeaker to give out alarm sound. This circuit can output any sound, but requires the MCU to support the sound output I2S port, placing higher demands on the MCU, and the cost of the MCU is higher.

SUMMERY OF THE UTILITY MODEL

The to-be-solved technical problem of the utility model is to the alarm sound drive circuit among the automobile combination instrument, how under the prerequisite that does not increase the MCU cost, realize high-quality sound.

In order to solve the technical problem, the technical scheme of the utility model provide an automobile instrument alarm sound drive arrangement, a serial communication port, include:

the MCU microcontroller is provided with an output interface of a Pulse Width Modulation (PWM) signal representing volume and an output interface of a PWM signal representing tone;

the volume low-pass filter is used for converting the Pulse Width Modulation (PWM) signal which represents the volume and is output by the MCU microcontroller into a direct current voltage signal which represents the volume;

the tone amplitude modulator is used for modulating the amplitude of the PWM signal which represents the tone and is output by the MCU microcontroller into the amplitude of the direct-current voltage signal, and combining the amplitude of the PWM signal with the direct-current voltage signal to form a PWM sound signal with tone and volume;

a tone low pass filter for filtering the PWM sound signal carrying tone and volume into a sine wave sound signal;

the sound power amplifier is used for amplifying the sine wave sound signal and further driving the loudspeaker to give out an alarm sound;

the volume low-pass filter, the tone amplitude modulator, the tone low-pass filter, the sound power amplifier and the loudspeaker are sequentially connected, an output interface of a Pulse Width Modulation (PWM) signal representing volume on the MCU microcontroller is connected with an input end of the volume low-pass filter, and an output interface of the PWM signal representing tone on the MCU microcontroller is connected with an input end of the tone low-pass filter.

Preferably, the volume low-pass filter is formed by connecting an RC low-pass filter and a voltage follower.

More preferably, the RC low-pass filter includes a first capacitor and a third resistor, the voltage follower is a first operational amplifier, one end of the third resistor is connected to an output interface of a pulse width modulation PWM signal representing volume on the MCU microcontroller, the other end of the third resistor is connected to one end of the first capacitor and a non-inverting input terminal of the first operational amplifier, and the other end of the first capacitor is grounded; the inverting input end of the first operational amplifier is connected with the output end of the first operational amplifier.

Preferably, the tone amplitude modulator is composed of a pull-up resistor and a switch tube connection with an open circuit output.

More preferably, the tone amplitude modulator includes a fourth resistor, a first triode and a sixth resistor, one end of the fourth resistor is connected to an output interface of a PWM signal representing a tone on the MCU microcontroller, the other end of the fourth resistor is connected to a base of the first triode, one end of the sixth resistor is connected to an output end of the first operational amplifier, the other end of the sixth resistor is connected to a collector of the first triode, and an emitter of the first triode is grounded.

Preferably, the pitch low-pass filter is composed of a Sallen-Key low-pass filter and a bias resistor connection.

More preferably, the tone low-pass filter includes a fourth capacitor, one end of the fourth capacitor is connected to the collector of the first triode, the other end of the fourth capacitor is connected to one end of a second resistor and one end of a seventh resistor, the other end of the second resistor is connected to the working power supply, the other end of the seventh resistor is connected to one end of the second capacitor and one end of the first resistor, the other end of the first resistor is connected to one end of the third capacitor and the non-inverting input end of the second operational amplifier, the other end of the third capacitor is grounded, one end of a tenth resistor is connected to the inverting input end of the second operational amplifier and one end of a ninth resistor, the other end of the tenth resistor is grounded, and the other end of the second capacitor and the other.

Preferably, the acoustic power amplifier is a transmitter follow push-pull output amplifier.

More preferably, the sound power amplifier includes a fifth resistor, one end of the fifth resistor is connected to the output end of the second operational amplifier, the other end of the fifth resistor is connected to the base of the second triode and the base of the third triode, the collector of the second triode is grounded, the collector of the third triode is connected to the power supply, the emitter of the second triode and the emitter of the third triode are both connected to one end of a fifth capacitor, and the other end of the fifth capacitor is connected to the speaker.

When the automobile instrument alarm sound driving device provided by the utility model is used, the MCU microcontroller outputs the pulse width modulation PWM signal representing the volume and the PWM signal representing the tone, and the pulse width modulation PWM signal representing the volume is converted into a direct current voltage signal representing the volume through the volume low-pass filter; the direct current voltage signal and the PWM signal representing the tone are converted into a PWM sound signal through a tone amplitude modulator; the PWM sound signal is filtered into a sine wave sound signal through a low-pass filter; the sound power amplifier amplifies the sine wave sound signal, and the amplified sound signal is used for driving a loudspeaker to give an alarm sound.

The utility model provides a device has overcome prior art's not enough, and the volume and the tone of alarm sound are controlled respectively by two way pulse width modulation PWM signals, separate the tone and the volume of sound and come independent control, can realize high-quality sound, do not increase MCU's cost again.

Drawings

Fig. 1 is a block diagram of an automobile instrument alarm sound driving device according to an embodiment of the present invention;

fig. 2 is a circuit diagram of an automobile instrument alarm sound driving device according to an embodiment of the present invention;

fig. 3 is an embodiment of the present invention provides an input/output signal waveform diagram of an alarm sound driving device for an automobile instrument.

Detailed Description

Fig. 1 is the utility model discloses an embodiment provides a motormeter alarm sound drive arrangement's block diagram, motormeter alarm sound drive arrangement include:

the volume low-pass filter 1 is used for converting a Pulse Width Modulation (PWM) signal 6 which represents the volume and is output by the MCU microcontroller into a direct current voltage signal 7 which represents the volume;

the tone amplitude modulator 2 is used for modulating the amplitude of a PWM signal 8 which represents the tone and is output by the MCU microcontroller into the amplitude of a direct current voltage signal 7, and combining the amplitude of the PWM signal with the direct current voltage signal 7 to form a PWM sound signal 9 with the tone and the volume;

a tone low pass filter 3 for filtering a PWM sound signal 9 carrying a tone and a volume into a sine wave sound signal 10;

the audio power amplifier 4 amplifies the sinusoidal sound signal 10 to form an amplified sound signal 11, and the amplified sound signal 11 drives the speaker 5 to generate an alarm sound.

The volume low-pass filter 1, the tone amplitude modulator 2, the tone low-pass filter 3, the sound power amplifier 4 and the loudspeaker 5 are sequentially connected, and the MCU microcontroller is connected with the volume low-pass filter 1 and the tone low-pass filter 3.

The MCU microcontroller outputs a Pulse Width Modulation (PWM) signal 6 representing volume and a PWM signal 8 representing tone, the PWM signal 6 representing volume is converted into a direct current voltage signal 7 representing volume through a volume low-pass filter 1, and the direct current voltage signal 7 and the PWM signal 8 representing tone are converted into a PWM sound signal 9 through a tone amplitude modulator 2; the PWM sound signal 9 is filtered into a sine wave sound signal 10 through a low-pass filter 3; the audio power amplifier 4 amplifies a sinusoidal sound signal 10, and the amplified sound signal 11 is used to drive the speaker 5 to generate an alarm sound.

Fig. 2 is a circuit diagram of the driving device for warning sounds of an automobile instrument according to the present embodiment. The first capacitor C1, the third resistor R3 and the first operational amplifier U1 form a volume low-pass filter 1. One end of a third resistor R3 is connected with an interface of the MCU, which is used for outputting a Pulse Width Modulation (PWM) signal 6 representing the volume, the other end of the third resistor R3 is connected with one end of a first capacitor C1 and the non-inverting input end of a first operational amplifier U1, and the other end of the first capacitor C1 is grounded; the inverting input of the first operational amplifier U1 is connected to the output of the first operational amplifier U1.

The volume low pass filter 1 converts a pulse width modulated PWM signal 6 representative of the volume output by the MCU into a dc voltage signal 7 representative of the volume. The voltage of the output dc voltage signal 7 ranges from 0V to the logic level VDD of the MCU. A PWM of 0% duty cycle corresponds to a minimum voltage of 0V and a PWM of 100% duty cycle corresponds to a maximum voltage VDD. The first capacitor C1 and the third resistor R3 form an RC low-pass filter, and the first operational amplifier U1 is a voltage follower.

The fourth resistor R4, the first transistor Q1 and the sixth resistor R6 form the tone amplitude modulator 2. One end of a fourth resistor R4 is connected with an interface of the MCU, which is used for representing the PWM signal 8 of the tone, the other end of the fourth resistor R4 is connected with the base electrode of a first triode Q1, one end of a sixth resistor R6 is connected with the output end of a first operational amplifier U1 of the volume low-pass filter 1, the other end of the sixth resistor R6 is connected with the collector electrode of a first triode Q1, and the emitter electrode of the first triode Q1 is grounded.

The tone amplitude modulator 2 modulates the amplitude of the PWM signal 8 representing the tone output by the MCU into the amplitude of the dc voltage signal 7. The duty cycle of the PWM signal 8 representing the tone is fixed at 50%, and PWM signals of different frequencies correspond to sounds of different tones. The fourth resistor R4 and the first transistor Q1 form a switch circuit, and the output of the switch circuit is pulled up to the output of the volume low-pass filter 1 through the sixth resistor R6. After the tone PWM signal outputted from the MCU passes through the first transistor Q1, the amplitude is converted from the logic voltage VDD of the MCU to the amplitude of the dc voltage signal 7 representing the volume.

The second capacitor C2, the third capacitor C3, the fourth capacitor C4, the first resistor R1, the second resistor R2, the seventh resistor R7, the ninth resistor R9, the tenth resistor R10, and the second operational amplifier U2 constitute the sound signal low-pass filter 3. One end of a fourth capacitor C4 is connected to the collector of the first triode Q1, the other end of the fourth capacitor C4 is connected to one end of a second resistor R2 and one end of a seventh resistor R7, the other end of the second resistor R2 is connected to the working power VDD, the other end of the seventh resistor R7 is connected to one end of a second capacitor C2 and one end of a first resistor R1, the other end of the first resistor R1 is connected to one end of a third capacitor C3 and the non-inverting input end of the second operational amplifier U2, the other end of the third capacitor C3 is grounded, one end of a tenth resistor R10 is connected to the inverting input end of the second operational amplifier U2 and one end of a ninth resistor R9, the other end of the tenth resistor R10 is grounded, and the other ends of the second capacitor C2 and the ninth resistor R9 are both connected to.

The signal low pass filter 3 filters the PWM sound signal 9 carrying the tone and volume into a sine wave signal. The first resistor R1, the seventh resistor R7, the second capacitor C2, the third capacitor C3 and the second operational amplifier U2 form a basic topological structure of the Sallen-Key filter, the ninth resistor R9 and the tenth resistor R10 are used for setting the gain of the Sallen-Key filter, the fourth capacitor C4 is an alternating current coupling capacitor, and the second resistor R2 is used for setting the direct current bias level of an output signal and is used for matching a rear-stage power amplifier.

The fifth resistor R5, the fifth capacitor C5, the second transistor Q2 and the third transistor Q3 constitute the audio power amplifier 4. One end of a fifth resistor R5 is connected with the output end of the second operational amplifier U2, the other end of the fifth resistor R5 is connected with the base of the second triode Q2 and the base of the third triode Q3, the collector of the second triode Q2 is grounded, the collector of the third triode Q3 is connected with a power supply VCC, the emitter of the second triode Q2 and the emitter of the third triode Q3 are both connected with one end of a fifth capacitor C5, and the other end of the fifth capacitor C5 is connected with the loudspeaker 5.

The audio power amplifier 4 amplifies the sinusoidal audio signal and drives the speaker 5. The second triode Q2 and the third triode Q3 are power triodes, and form a transmitter follow push-pull output amplifier. The fifth resistor R5 provides the appropriate driving current for the second transistor Q2 and the third transistor Q3. The amplified sound signal drives the speaker 5 to generate an alarm sound through the fifth capacitor C5 dc blocking capacitor.

Fig. 3 is a waveform diagram of input and output signals of the driving device for warning sounds of an automobile instrument according to the present embodiment. Wherein, the frequency of the pulse width modulation PWM signal 6 which is output by the MCU and represents the volume is 20KHz, the duty ratio of 50 percent, and represents the volume of 50 percent; a PWM signal 8 which is output by the MCU and represents tones, and a square wave signal with the frequency of 1 KHz; the frequency of a PWM sound signal 9 which is output by the tone amplitude modulator and carries the tone and the volume is consistent with that of a PWM signal 8 which is output by the MCU and represents the tone, and the amplitude is modulated to be 50 percent; the sound signal 11 output by the sound power amplifier, namely the signal waveform on the loudspeaker, is a sine wave signal of 1 KHz. By varying the duty cycle of the pulse width modulated PWM signal 6 representing the volume, sinusoidal signals of different amplitudes can be output, and by varying the frequency of the PWM signal 8 representing the tone, sinusoidal signals of different frequencies can be output.

It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element may be termed a second element, and, similarly, a second element may be termed a first element, without departing from the scope of example embodiments.

The foregoing is merely a preferred embodiment of the present invention, and is not intended to limit the present invention in any way and in any way, and it should be understood that modifications and additions may be made by those skilled in the art without departing from the method of the present invention, and such modifications and additions are also considered to be within the scope of the present invention. Those skilled in the art can make various changes, modifications and evolutions equivalent to those made by the above-disclosed technical content without departing from the spirit and scope of the present invention, and all such changes, modifications and evolutions are equivalent embodiments of the present invention; meanwhile, any changes, modifications and evolutions of equivalent changes to the above embodiments according to the actual technology of the present invention are also within the scope of the technical solution of the present invention.

Claims

1. An automobile instrument alarm sound driving device, characterized by comprising:

an MCU microcontroller provided with an output interface for a Pulse Width Modulation (PWM) signal (6) representing the volume and an output interface for a PWM signal (8) representing the tone;

a volume low-pass filter (1) for converting a Pulse Width Modulation (PWM) signal (6) representative of the volume output by the MCU microcontroller into a direct current voltage signal (7) representative of the volume;

a tone amplitude modulator (2) for modulating the amplitude of a PWM signal (8) representative of the tone output by the MCU microcontroller to the amplitude of the DC voltage signal (7) and combining with the DC voltage signal (7) to form a PWM sound signal (9) carrying the tone and volume;

a pitch low pass filter (3) for filtering the PWM sound signal (9) carrying the pitch and volume into a sinusoidal sound signal (10);

the sound power amplifier (4) is used for amplifying the sine wave sound signal (10) and further driving a loudspeaker (5) to give out alarm sound;

the volume low-pass filter (1), the tone amplitude modulator (2), the tone low-pass filter (3), the sound power amplifier (4) and the loudspeaker (5) are sequentially connected, an output interface of a Pulse Width Modulation (PWM) signal (6) representing the volume on the MCU microcontroller is connected with the input end of the volume low-pass filter (1), and an output interface of a PWM signal (8) representing the tone on the MCU microcontroller is connected with the input end of the tone low-pass filter (3).

2. The automobile instrument alarm sound driving device according to claim 1, characterized in that: the volume low-pass filter (1) is formed by connecting an RC low-pass filter and a voltage follower.

3. The automobile instrument alarm sound driving device according to claim 2, characterized in that: the RC low-pass filter comprises a first capacitor (C1) and a third resistor (R3), the voltage follower is a first operational amplifier (U1), one end of the third resistor (R3) is connected with an output interface of a Pulse Width Modulation (PWM) signal (6) representing volume on the MCU microcontroller, the other end of the third resistor (R3) is connected with one end of a first capacitor (C1) and a non-inverting input end of a first operational amplifier (U1), and the other end of the first capacitor (C1) is grounded; the inverting input terminal of the first operational amplifier (U1) is connected to the output terminal of the first operational amplifier (U1).

4. A driving device for an alarm sound of an automobile instrument according to claim 3, wherein: the tone amplitude modulator (2) is formed by connecting a pull-up resistor and a switching tube with an open-circuit output.

5. The automobile instrument alarm sound driving device according to claim 4, wherein: the tone amplitude modulator (2) comprises a fourth resistor (R4), a first triode (Q1) and a sixth resistor (R6), one end of the fourth resistor (R4) is connected with an output interface of a PWM signal (8) representing tones on the MCU microcontroller, the other end of the fourth resistor (R4) is connected with a base electrode of the first triode (Q1), one end of the sixth resistor (R6) is connected with an output end of the first operational amplifier (U1), the other end of the sixth resistor (R6) is connected with a collector electrode of the first triode (Q1), and an emitter electrode of the first triode (Q1) is grounded.

6. The automobile instrument alarm sound driving device according to claim 5, characterized in that: the tone low-pass filter (3) is formed by connecting a Sallen-Key low-pass filter and a bias resistor.

7. The automobile instrument alarm sound driving device according to claim 6, characterized in that: the tone low-pass filter (3) comprises a fourth capacitor (C4), one end of the fourth capacitor (C4) is connected with a collector of a first triode (Q1), the other end of the fourth capacitor (C4) is connected with one end of a second resistor (R2) and one end of a seventh resistor (R7), the other end of a second resistor (R2) is connected with a working power supply (VDD), the other end of the seventh resistor (R7) is connected with one end of a second capacitor (C2) and one end of a first resistor (R1), the other end of the first resistor (R1) is connected with one end of a third capacitor (C3) and a non-inverting input end of a second operational amplifier (U2), the other end of the third capacitor (C3) is grounded, one end of a tenth resistor (R10) is connected with an inverting input end of the second operational amplifier (U2) and one end of a ninth resistor (R9), the other end of the tenth resistor (R10) is grounded, and the other end of the second capacitor (C2) and the ninth resistor (R9) are both connected with an output end of.

8. The automobile instrument alarm sound driving apparatus as set forth in claim 7, wherein: the sound power amplifier (4) is a transmitter follow push-pull output amplifier.

9. The automobile instrument alarm sound driving apparatus as set forth in claim 8, wherein: the sound power amplifier (4) comprises a fifth resistor (R5), one end of the fifth resistor (R5) is connected with the output end of the second operational amplifier (U2), the other end of the fifth resistor (R5) is connected with the base of the second triode (Q2) and the base of the third triode (Q3), the collector of the second triode (Q2) is grounded, the collector of the third triode (Q3) is connected with the power supply (VCC), the emitter of the second triode (Q2) and the emitter of the third triode (Q3) are both connected with one end of a fifth capacitor (C5), and the other end of the fifth capacitor (C5) is connected with the loudspeaker (5).