CN109932603A - A kind of air conditioner electric control board buzzer sound detection method and circuit board - Google Patents

Abstract

The invention discloses a kind of air conditioner electric control plate buzzer sounding detection methods, obtain the audio signal that one section of superposition will be obtained when buzzer sounding by analyzing；Following result a: DC component is obtained by introducing Fourier transformation again, and a fundamental wave is primary, secondary, three times and higher hamonic wave；By microphone samples audio signal, then filtering out higher hamonic wave using second order passive bandpass filters obtains the fundamental wave of passband, amplifier is calculated by hardware amplifier again, waveform after amplifying sampling filter, again the AD conversion unit of Waveform Input microprocessor is converted into digital quantity signal in real time and records maximum component value, it is compared within the unit time using maximum component value and preset numerical value, meet condition MCU control relay to be attracted, being unsatisfactory for condition, then relay is failure to actuate.The invention also discloses a kind of air conditioner electric control plate buzzer sounding detection circuit boards.The present invention, which solves, manually to listen sounding to be easy to produce to fail to judge, and is easy the defect interfered by environmental noise.

Description

A kind of air conditioner electric control board buzzer sound detection method and circuit board

technical field

The invention relates to the technical field of air-conditioning equipment detection, in particular to a method and a circuit board for detecting the sound of a buzzer of an air-conditioning electronic control board.

Background technique

After the electric control panel of the air conditioner is produced and processed, it is necessary to energize the electric control panel of the air conditioner to check whether its performance and other functions can meet the customer's requirements. In the detection process, one of the items needs to determine whether the buzzer element on the electronic control board is sounding normally. At present, the detection method adopts artificial ears to listen to whether the buzzer sounds normally. The main disadvantage: artificial listening is prone to missed judgments, and it is easily disturbed by environmental noise. There is no standard quantification for the sound of the buzzer heard by different people.

Accordingly, there is an urgent need for a method and a circuit board for detecting the sound of a buzzer of an air conditioner electric control board, which is not easy to miss judgment and is objective.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a method and a circuit board for detecting the sound of a buzzer of an air conditioner electric control board, which is not easy to miss judgment and is objective.

The present invention adopts the following technical solutions to solve the above-mentioned technical problems:

A method for detecting sound of a buzzer on an air conditioner electronic control panel, the method includes the following processes:

S1. First of all, through analysis, a superimposed audio signal will be obtained when the buzzer sounds, and its mathematical function model is y=sinx+1/2*sin 2x+1/3*sin 3x+1/4*sin 4x+ ..., according to the principle of Fourier series, periodic functions can be expanded into the sum of a constant and a set of sine and cosine functions with a common period;

S2. Secondly, the following results are obtained by introducing Fourier transform. For any compound periodic vibration function y(T), it can be expressed by Fourier series decomposition: a DC component, a fundamental wave, a first harmonic, a second harmonic , the third harmonic, the higher harmonic;

S3. Finally, by using the collective microphone sampling and filtering circuit, the microphone samples the audio signal and then uses the second-order passive band-pass filter to filter out the high-order harmonics to obtain the fundamental wave of the pass frequency, and then passes the hardware operational amplifier to amplify the The waveform after sampling and filtering is converted into a digital signal in real time by the AD conversion unit that inputs the waveform into the microprocessor and records the maximum component value. The maximum component value is compared with the preset value within a unit time, and the condition MCU is satisfied. Through the pin control relay pull-in, if the conditions are not met, the relay will not act, so as to judge whether the buzzer sound is normal.

As one of the preferred modes of the present invention, the specific analysis process of the step S1 is:

where ω=2π/T;

n = 0, 1, 2, 3, ...;

n=1, 2, 3, 4, ...;

At the discontinuity point, the following equation holds:

a0/2 is the DC component of the signal f(t);

make

c1 is the amplitude of the fundamental wave, cn is the amplitude of the n-th harmonic; c1 is sometimes called the amplitude of the first harmonic; a0/2 is sometimes called the amplitude of the 0-th harmonic.

As one of the preferred modes of the present invention, the resident collective microphone sampling and filtering circuit includes VCC5V, R16, R10, R9, C4, C2, R14, MIC pickup, C9, C7, R7, R5, R3, the VCC5V, R16, R10, R9, C4, and C2 are connected in series in sequence, and one end of the R14 and the MIC pickup, C9, C7 and R7, R5, and R3 are connected in parallel between R16 and R10, between R10 and R9, and between R9 and C4. Between C4 and C2, the end of C2, and the other end are grounded, and the 2 pin of the MIC pickup is grounded.

As one of the preferred modes of the present invention, the R10, C9, R9, C7, R7, C4, R5, C2, and R3 form a second-order passive Pi-type bandpass filter to filter the waveform so that only those satisfying 4K Hz Only the frequency can pass through, so as to filter out the interference of environmental noise.

As one of the preferred modes of the present invention, the hardware operational amplifier is a proportional amplifier circuit composed of an LM358 integrated operational amplifier chip.

As one of the preferred modes of the present invention, the collective microphone sampling and filtering circuit is placed in a fixed position close to the buzzer to capture the frequency and amplitude of the buzzer when it is working.

The invention also discloses a circuit board for detecting the sound of a buzzer of an air conditioner electric control board. When the circuit board is in the detection operation, it performs tasks according to the detection process of the method for detecting the sound of the buzzer of the electric control board of the air conditioner.

Compared with the prior art, the present invention has the advantages that the detection method of the present invention captures the frequency and amplitude emitted by the buzzer by placing the detection circuit at a fixed position close to the buzzer, and then converts it into an analog voltage signal and uses a microcomputer The processing unit automatically determines whether the buzzer is working normally and gives a digital signal through the relay, which solves the defects that artificial listening is prone to omission of judgment and is easily disturbed by environmental noise.

Description of drawings

Fig. 1 is the flow chart of the sounding detection method of the buzzer of the air conditioner electric control panel in the embodiment;

Fig. 2 is the combined waveform diagram in the embodiment;

Fig. 3 is the mathematical function model waveform diagram of pure sound in the embodiment;

Fig. 4 is the combined sound mathematical function model waveform diagram in the embodiment;

5 is a schematic diagram 1 of the overall detection circuit in the embodiment;

6 is a schematic diagram 2 of the overall detection circuit in the embodiment;

FIG. 7 is a schematic diagram of the sampling and filtering circuit of the collective microphone in the embodiment;

Fig. 8 is the amplitude-frequency, phase-frequency characteristic function image of the second-order passive Pi-type bandpass filter in the embodiment;

Fig. 9 is the obstruction diagram that uses the baud meter to measure the second-order band-pass filter to the center pass frequency 4Khz has -5 decibels in the embodiment;

FIG. 10 is a schematic diagram of a proportional amplification circuit composed of an LM358 integrated operational amplifier chip in the embodiment;

FIG. 11 is a schematic diagram of the circuit board PCB in the embodiment.

Detailed ways

The embodiments of the present invention are described in detail below. This embodiment is implemented on the premise of the technical solution of the present invention, and provides a detailed implementation manner and a specific operation process, but the protection scope of the present invention is not limited to the following implementation. example.

The design principle of the present invention:

The composition of the audio can be obtained by analyzing the frequency spectrum of the audio: including the following points (amplitude, frequency, harmonics), a piece of audio is a combined waveform with many sinusoidal signals of different frequencies and different amplitudes superimposed as shown in Figure 2;

A pure sound mathematical function model is y=Asinωx waveform as shown in Figure 3;

The sounds heard by the human ear in nature are composed of various waveforms, so the mathematical function model of this sound is y=sinx+1/2*sin 2x+1/3*sin 3x+1/4*sin 4x+…; as shown in Figure 4;

The working principle of the buzzer on the air-conditioning electronic control board product is to drive the buzzer to sound by giving a square wave with a fixed 4K frequency through the single-chip microcomputer.

Example 1

Based on the above design principles: refer to Figure 1: a method for detecting the sound of a buzzer on an air conditioner electronic control panel in this embodiment, the method includes the following processes:

S1. First of all, through analysis, a superimposed audio signal will be obtained when the buzzer sounds, and its mathematical function model is y=sinx+1/2*sin 2x+1/3*sin 3x+1/4*sin 4x+ ..., according to the principle of Fourier series, periodic functions can be expanded into the sum of a constant and a set of sine functions and cosine functions with a common period; the specific analysis process is:

where ω=2π/T;

n = 0, 1, 2, 3, ...;

n=1, 2, 3, 4, ...;

At the discontinuity point, the following equation holds:

a0/2 is the DC component of the signal f(t);

make

c1 is the amplitude of the fundamental wave, cn is the amplitude of the n-th harmonic; c1 is sometimes called the amplitude of the first harmonic; a0/2 is sometimes called the amplitude of the 0-th harmonic.

S2. Secondly, the following results are obtained by introducing Fourier transform. For any compound periodic vibration function y(T), it can be expressed by Fourier series decomposition: a DC component, a fundamental wave, a first harmonic, a second harmonic , the third harmonic, the higher harmonic;

S3. Finally, by using the collective microphone sampling and filtering circuit, the microphone samples the audio signal and then uses the second-order passive band-pass filter to filter out the high-order harmonics to obtain the fundamental wave of the pass frequency, and then passes the hardware operational amplifier to amplify the The waveform after sampling and filtering is converted into a digital signal in real time by the AD conversion unit that inputs the waveform into the microprocessor and records the maximum component value. The maximum component value is compared with the preset value within a unit time, and the condition MCU is satisfied. The pull-in of the relay is controlled by the pin. If the condition is not met, the relay will not act, so as to judge whether the buzzer sounds normal; the circuit schematic diagram is shown in Figure 5-6.

The detection method of this embodiment captures the frequency and amplitude emitted by the buzzer by placing the detection circuit at a fixed position close to the buzzer, and then converts it into an analog voltage signal and uses a microprocessor unit to automatically determine whether the buzzer works normally or not. And the digital signal is given through the relay, which solves the defect that artificial listening is prone to omission of judgment and is easily disturbed by environmental noise.

Example 2

This embodiment is basically the same as Embodiment 1, and the main difference is that, as shown in FIG. 7 : the resident collective microphone sampling and filtering circuit includes VCC5V, R16, R10, R9, C4, C2, R14, MIC pickup, C9, C7 , R7, R5, R3, the VCC5V, R16, R10, R9, C4, C2 are connected in series in sequence, the R14 and the MIC pickup, C9, C7 and R7, R5, R3 one end in parallel between R16 and R10 in turn , between R10 and R9, between R9 and C4, between C4 and C2, the end of C2, the other end is grounded, and the 2 pin of the MIC pickup is grounded;

In this embodiment, when the 5V voltage flows through R16 and R14, a fixed potential is generated at point A. When the external audio is changed, the MIC pickup is vibrated by sound waves. When the inner group of the MIC changes, the voltage at point A changes. When the audio sounds continuously When changing, the voltage at point A also sends continuous transformation, which is a sine function of composite superposition from a mathematical point of view. Since our buzzer uses a fixed frequency to sound, we only need the fundamental wave of 4K, and the frequency at point A is a composite superimposed waveform. Therefore, the circuit introduces R10, C9, R9, C7, R7, C4, R5, C2, R3 form a second-order passive Pi-type band-pass filter to filter the waveform of point A so that only the frequency that meets 4K Hz can pass through, so as to filter out the interference of environmental noise .

Example 3

This embodiment is basically the same as Embodiment 1, and the main difference is that the hardware operational amplifier is a proportional amplifier circuit composed of an LM358 integrated operational amplifier chip, and the collective microphone sampling and filtering circuit is placed close to the buzzer. The fixed position of the buzzer is used to capture the frequency and amplitude of the buzzer when it is working; in this embodiment, the amplifying circuit and the proximity of the buzzer reduce the interference of judgment and improve the detection accuracy.

Example 4

This embodiment also discloses a circuit board for detecting the sound of a buzzer of an air conditioner electric control board. When the circuit board is in the detection operation, the task is performed according to the detection process of the method for detecting the sound of a buzzer of an air conditioner electric control board.

The present invention filters the waveform of point A through a second-order passive Pi-type band-pass filter, so that only the frequency that meets 4K Hz can pass through, so as to filter out the interference of environmental noise; its amplitude-frequency and phase-frequency characteristic function images are shown in Figure 8 , the center pass frequency calculation formula is: Then use the baud meter to measure that the second-order band-pass filter has a -5dB obstruction to the center pass frequency of 4Khz, as shown in Figure 9;

After the signal reaches point B through the band-pass filter, it enters the operational amplifier to amplify the signal, and then the analog signal is converted into a digital signal in the AD conversion module that inputs the signal to the microprocessor. The operational amplifier circuit as shown in Figure 10 uses the LM358 integrated operational amplifier chip to form a proportional amplifier circuit. MCU_AD=(1+R8/R17) SourceIn, the voltage is amplified by the B power to the operational amplifier circuit and then enters the MCU and compares with the set value; then the MCU performs the logic control relay action, and the circuit board PCB is shown in Figure 11. Show.

The above descriptions are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included in the protection of the present invention. within the range.

Claims (7)

1. A method for detecting sound of an air conditioner electric control panel buzzer, characterized in that the method comprises the following processes: S1. First of all, through analysis, it is concluded that a superimposed audio signal will be obtained when the buzzer sounds, and its mathematical function model is y=sinx+1/2*sin2x+1/3*sin3x+1/4*sin4x+…, according to According to the principle of Fourier series, periodic functions can be expanded into the sum of a constant and a set of sine and cosine functions with a common period; S2. Secondly, the following results are obtained by introducing Fourier transform. For any compound periodic vibration function y(T), it can be expressed by Fourier series decomposition: a DC component, a fundamental wave, a first harmonic, a second harmonic , the third harmonic, the higher harmonic; S3. Finally, by using the collective microphone sampling and filtering circuit, the microphone samples the audio signal and then uses the second-order passive band-pass filter to filter out the high-order harmonics to obtain the fundamental wave of the pass frequency, and then passes the hardware operational amplifier to amplify the The waveform after sampling and filtering is converted into a digital signal in real time by the AD conversion unit that inputs the waveform into the microprocessor and records the maximum component value. The maximum component value is compared with the preset value within a unit time, and the condition MCU is satisfied. Through the pin control relay pull-in, if the conditions are not met, the relay will not act, so as to judge whether the buzzer sound is normal. 2. The method for detecting sound of a buzzer of an air conditioner electric control panel according to claim 1, wherein the specific analysis process of the step S1 is: where ω=2π/T; n = 0, 1, 2, 3, ...; n=1, 2, 3, 4, ...; At the discontinuity point, the following equation holds: a0/2 is the DC component of the signal f(t); make c1 is the amplitude of the fundamental wave, cn is the amplitude of the n-th harmonic; c1 is sometimes called the amplitude of the first harmonic; a0/2 is sometimes called the amplitude of the 0-th harmonic. 3. The method for detecting sound of a buzzer of an air conditioner electronic control panel according to claim 1, wherein the sampling and filtering circuit of the resident collective microphone comprises VCC5V, R16, R10, R9, C4, C2, R14, MIC pickups , C9, C7, R7, R5, R3, the VCC5V, R16, R10, R9, C4, C2 are connected in series in turn, the R14 and the MIC pickup, C9, C7 and one end of R7, R5, R3 are connected in parallel to R16 Between R10, between R10 and R9, between R9 and C4, between C4 and C2, the end of C2, and the other end are all grounded, and the 2 pin of the MIC pickup is grounded. 4. The method for detecting sound of a buzzer of an air conditioner electronic control panel according to claim 3, wherein the R10, C9, R9, C7, R7, C4, R5, C2, and R3 form a second-order passive Pi The type band-pass filter filters the waveform so that only the frequency that meets 4K Hz can pass, so as to filter out the interference of environmental noise. 5 . The method for detecting sound of a buzzer of an air conditioner electronic control board according to claim 1 , wherein the hardware operational amplifier is a proportional amplifier circuit composed of an LM358 integrated operational amplifier chip. 6 . 6. The method for detecting the sound of a buzzer of an air-conditioning electronic control panel according to claim 1, wherein the sampling and filtering circuit of the collective microphone is placed at a fixed position close to the buzzer to capture the buzzer and emit when the buzzer is working. frequency and amplitude. 7. A circuit board for detecting the sound of a buzzer of an air conditioner electric control panel, characterized in that, when the circuit board is in the detection operation, the task is performed according to the detection process of the method for detecting the sound of a buzzer of an air conditioner electric control panel.