A capacitive load voltage correction circuit

Abstract

This invention discloses a capacitive load voltage correction circuit, including a load driving circuit connected to the capacitive load and a voltage correction circuit connected to the load driving circuit. The voltage correction circuit calculates the voltage value corresponding to the actual AC signal output by the load driving circuit, and adjusts the voltage of the actual AC signal according to the voltage value to calibrate it to the driving voltage required to drive the capacitive load. This invention adjusts the driving voltage of the capacitive load by adding a voltage correction circuit, making the driving voltage output to each channel of the capacitive load consistent or nearly consistent, thereby improving the listening experience of audio signals played by the capacitive load and achieving automatic calibration of the driving voltage of the multi-channel capacitive load.

Description

Technical Field

[0001] This utility model relates to the field of capacitive load testing technology, specifically to a capacitive load voltage correction circuit. Background Technology

[0002] During the production testing of capacitive loads, the main parameters are L (inductance), C (capacitance), and R (resistance). Furthermore, the power amplifier chip output has an LC filter circuit (not shown in the diagram). In the signal circuit, the performance parameters of the inductor and capacitor have error ranges. Therefore, the complex impedance of the capacitive load and the LC circuit are different in each channel's signal circuit. Consequently, even if the gain setting for each channel is the same in the pre-amplifier signal processing chip, the voltage of the capacitive load on each channel will be different after power amplification by the power amplifier chip, leading to different sound pressure levels and affecting the listening experience.

[0003] Therefore, it is necessary to solve the problem that different voltages on the channels affect the listening experience in existing multi-channel capacitive load tests. Utility Model Content

[0004] The purpose of this invention is to provide a capacitive load voltage correction circuit that can calibrate the drive voltages on multiple channels of a capacitive load to a consistent capacitive load voltage.

[0005] To achieve the above objectives, this utility model proposes a directional capacitive load voltage correction circuit, comprising:

[0006] A load driving circuit, the output of which is connected to the capacitive load, and which includes at least a signal processing unit and a power amplifier connected to the signal processing unit. The signal processing unit is used to process the audio signal and amplify it by the power amplifier to output an actual AC signal for driving the capacitive load.

[0007] The voltage correction circuit includes at least a DC blocking voltage divider circuit, a DC bias circuit, and a microcontroller unit. The DC blocking voltage divider circuit is connected to the power amplifier and is used to block and step down the actual AC signal. The DC bias circuit is connected to the DC blocking voltage divider circuit and is used to apply a DC bias voltage to the stepped-down actual AC signal. The microcontroller unit is connected to the DC bias circuit and a signal processing unit and is used to calculate the voltage value corresponding to the actual AC signal based on the applied DC bias voltage. It then compares the voltage value with a preset voltage and determines whether the error between the two is within a preset error range. If the error is not within the error range, the signal processing unit is fed back to adjust the voltage magnitude of the actual AC signal through gain setting to calibrate it to the driving voltage required to drive the capacitive load.

[0008] In a preferred embodiment, the voltage correction circuit further includes a rectifier circuit connected to the DC bias circuit, used to convert the actual AC signal after applying a DC bias voltage into a stable DC signal; and the microcontroller unit is connected to the rectifier circuit, used to calculate the voltage value corresponding to the DC signal.

[0009] In a preferred embodiment, the DC blocking voltage divider circuit specifically includes a first DC blocking capacitor, a first voltage divider resistor, and a second voltage divider resistor. One end of the first DC blocking capacitor is connected to the power amplifier, and the other end is connected to one end of the first voltage divider resistor. The other end of the first voltage divider resistor is connected to one end of the second voltage divider resistor, and the other end of the second voltage divider resistor is grounded.

[0010] In a preferred embodiment, a second DC blocking capacitor is further connected between the DC blocking voltage divider circuit and the DC bias circuit.

[0011] In a preferred embodiment, the DC bias circuit includes a third voltage divider resistor and a fourth voltage divider resistor. One end of the third voltage divider resistor is connected to a DC power supply, and the other end is connected between the first voltage divider resistor and the second voltage divider resistor, as well as one end of the fourth voltage divider resistor. The other end of the fourth voltage divider resistor is grounded.

[0012] In a preferred embodiment, the rectifier circuit includes a rectifier diode and an integrator circuit. The integrator circuit includes a load resistor and a filter capacitor connected in parallel. The positive terminal of the rectifier diode is connected between the third and fourth voltage divider resistors, and the negative terminal is connected to one end of the load resistor. The other end of the load resistor is connected to the microcontroller unit. One end of the filter capacitor is connected between the load resistor and the microcontroller unit, and the other end is grounded.

[0013] In a preferred embodiment, the voltage correction circuit further includes a discharge circuit connected to the rectifier circuit, the discharge circuit including a fast discharge resistor connected in parallel with the filter capacitor.

[0014] In a preferred embodiment, the microcontroller unit includes an analog-to-digital converter (ADC), a filtering unit, and a voltage calculation unit. The ADC is connected to the DC bias circuit or the rectifier circuit and is used to sample the received signal and convert it into binary code. The filtering unit is connected to the ADC and is used to filter the digital signal. The voltage calculation unit is connected to the filtering unit and is used to calculate the voltage of the filtered digital signal to obtain the voltage value corresponding to the actual AC signal.

[0015] In a preferred embodiment, the capacitive load is an electrostatic ultrasonic transducer with multiple sound transmission channels. After voltage correction by the correction circuit, the driving voltage of each sound transmission channel is the same.

[0016] In a preferred embodiment, a DC bias voltage generating circuit is also connected between the output terminal of the load driving circuit and the capacitive load.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. This utility model adds a voltage correction circuit to process the AC signal at the output of the load drive circuit to obtain the voltage value corresponding to the signal. Based on the voltage value, the drive voltage of the capacitive load is adjusted so that the drive voltage output to each channel of the capacitive load is consistent or nearly consistent, thereby improving the listening effect of the audio signal played by the capacitive load and realizing the automatic calibration of the drive voltage of the multi-channel capacitive load.

[0019] 2. The voltage correction circuit added in this utility model has a simple structure, accurate and effective voltage feedback, and high testing efficiency. Attached Figure Description

[0020] Figure 1 This is a block diagram illustrating the principle of a capacitive load voltage correction circuit in one embodiment of the present invention.

[0021] Figure 2 This is a schematic block diagram of a capacitive load voltage correction circuit in another alternative embodiment of the present invention;

[0022] Figure 3 for Figure 2 A detailed circuit diagram of the embodiment. Detailed Implementation

[0023] The specific embodiments of this utility model are described in detail below, but it should be understood that the protection scope of this utility model is not limited to the specific embodiments.

[0024] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0025] Combination Figures 1-3As shown, the present invention discloses a capacitive load voltage correction circuit, including a load driving circuit and a voltage correction circuit connected to the load driving circuit. The output terminal of the load driving circuit is connected to the capacitive load. The voltage correction circuit processes the signal at the output terminal of the load driving circuit to obtain the voltage value corresponding to the signal, and adjusts the driving voltage of the capacitive load according to the voltage value, so that the driving voltage output to each channel of the capacitive load is consistent or nearly consistent, thereby improving the listening effect of the audio signal played by the capacitive load, and realizing the automatic calibration of the driving voltage of the multi-channel capacitive load.

[0026] Specifically, the load drive circuit includes at least a signal processing unit and a power amplifier. The signal processing unit receives the audio signal input (AC) and processes it, specifically modulating the audio signal with an ultrasonic carrier signal to create an ultrasonic modulated signal carrying the audio signal. The power amplifier, connected to the signal processing unit, amplifies the ultrasonic modulated signal. Additionally, a DC bias voltage generation circuit is connected between the output of the load drive circuit (specifically, the output of the power amplifier) ​​and the capacitive load. This circuit applies a DC bias signal to the AC signal output by the power amplifier. In practice, the DC bias signal voltage can be 200–300V, such as 300V. The capacitive load operates under the drive of the AC signal and the DC bias signal.

[0027] In one specific embodiment, the voltage correction circuit specifically includes a DC blocking voltage divider circuit, a DC bias circuit, and a microcontroller unit (MCU). The DC blocking voltage divider circuit is connected to a power amplifier and is used to block and reduce the voltage of the actual AC signal output by the load drive circuit. Combined with... Figure 3 As shown, in this embodiment, the DC blocking voltage divider circuit specifically includes a first DC blocking capacitor C1, a first voltage dividing resistor R1, and a second voltage dividing resistor R2. One end of the first DC blocking capacitor C1 is connected to the power amplifier, and the other end is connected to one end of the first voltage dividing resistor R1, used to block the DC signal in the actual AC signal. The other end of the first voltage dividing resistor R1 is connected to one end of the second voltage dividing resistor R2, and the other end of the second voltage dividing resistor R2 is grounded. That is, the voltage is divided by two resistors R1 and R2 connected in series, and the actual AC signal after DC blocking and voltage division is output between resistors R1 and R2. By modifying the resistance value of the voltage dividing resistor in the DC blocking voltage divider circuit, this invention allows the calibration circuit to be applicable to voltage calibration from tens of volts to hundreds of volts.

[0028] The DC bias circuit is used to adjust the actual AC signal to a suitable range, thereby avoiding subsequent distortion. In this embodiment, the DC bias circuit specifically includes a third voltage divider resistor R3 and a fourth voltage divider resistor R4. One end of the third voltage divider resistor R3 is connected to a DC power supply, such as a 3.3V DC power supply, and the other end is connected between the first voltage divider resistor R1 and the second voltage divider resistor R3 (i.e., the output of the DC blocking voltage divider circuit) and one end of the fourth voltage divider resistor R4. The other end of the fourth voltage divider resistor R4 is grounded.

[0029] Preferably, a second DC blocking capacitor C2 is connected between the DC blocking voltage divider circuit and the DC bias circuit. Specifically, one end of the second DC blocking capacitor C2 is connected between the first voltage divider resistor R1 and the second voltage divider resistor R2, and the other end is connected between the third voltage divider resistor R3 and the fourth voltage divider resistor R4, for further DC blocking processing of the actual AC signal after processing by the DC blocking voltage divider circuit.

[0030] like Figure 1 As shown, in one specific embodiment, the output of the DC bias circuit is directly connected to the microcontroller unit (MCU). The MCU calculates the voltage value corresponding to the actual AC signal based on the DC bias voltage applied by the DC bias circuit. Specifically, in this embodiment, the microcontroller unit can be an APM32E103xCxE series, which includes an analog-to-digital converter (ADC), a filtering unit, and a voltage calculation unit. The ADC is connected to the DC bias circuit and is used to sample the received signal and convert it into binary code. Specifically, it reads the actual AC signal through its ADC port and converts the actual AC signal into a digital signal. The filtering unit is connected to the ADC and is used to filter the digital signal. Filtering algorithms are used to remove noise and interference from the signal. Commonly used filtering algorithms include low-pass filtering, high-pass filtering, and band-pass filtering. The voltage calculation unit is connected to the filtering unit and is used to calculate the voltage value corresponding to the actual AC signal from the filtered digital signal. A voltage algorithm is used, such as calculating the actual voltage value using a formula:

[0031]

[0032] If the ADC's supply voltage is 3.3V and its resolution is 12 bits, then The voltage value corresponding to the actual AC signal can then be calculated.

[0033] Subsequently, the microcontroller unit (MCU) compares the voltage value with a preset voltage and determines whether the error between the two is within the preset error range. If it is not within the error range, the signal processing unit is notified to adjust the voltage of the actual AC signal through gain setting, calibrating it to the driving voltage required to drive the capacitive load. It should be noted that the filtering algorithm, voltage algorithm, and gain setting in the MCU and signal processing unit described above can be implemented using existing mature algorithms and software programs, and are not considered innovative designs of this utility model.

[0034] like Figure 2 As shown, in another alternative embodiment, a rectifier circuit is connected after the DC bias circuit to convert the actual AC signal with applied DC bias voltage into a stable DC signal. The microcontroller unit (MCU) is connected to this rectifier circuit to calculate the corresponding voltage value based on the converted DC signal. That is, unlike the previous embodiment, this embodiment adds a rectifier circuit, meaning the DC bias circuit is connected to the MCU via the rectifier circuit. Combined with... Figure 3 As shown, specifically in this embodiment, the rectifier circuit includes a rectifier diode D1 and an integrating circuit. The integrating circuit specifically includes a load resistor R5 and a filter capacitor C3 connected in parallel. The positive terminal of the rectifier diode D1 is connected between the third voltage divider resistor R3 and the fourth voltage divider resistor R4 (i.e., connected to the output of the DC bias circuit), and the negative terminal is connected to one end of the load resistor R5. The other end of the load resistor R5 is connected to the microcontroller unit (MCU). One end of the filter capacitor C3 is connected between the load resistor R5 and the MCU, and the other end is grounded. Preferably, a discharge circuit is also included to enable the rectified DC to respond quickly during rapid changes in the AC signal. In this embodiment, the discharge circuit includes a fast discharge resistor R6, which is connected in parallel with the filter capacitor C3.

[0035] In this embodiment, the microcontroller unit (MCU) calculates the voltage value corresponding to the actual AC signal after it has been converted into a DC signal. Compared to the MCU directly processing AC signals, processing DC signals is easier to implement in this embodiment. Apart from this, the module composition of the MCU, the principle and process of processing DC signals are the same as in the above embodiments, and will not be repeated here.

[0036] In implementation, the values ​​of each component in the above circuit can be as follows: the first DC blocking capacitor C1 is 0.1UF / 500V, the first voltage divider resistor R1 is 100KΩ, the second voltage divider resistor R2 is 1.65KΩ, the second DC blocking capacitor C2 is 2.2UF / 50V, the third voltage divider resistor R3 is 10KΩ, the fourth voltage divider resistor R4 is 10KΩ, the load resistor R5 is 100Ω, the filter capacitor C3 is 0.1UF / 50V, and the fast discharge resistor R6 is 1MΩ.

[0037] In implementation, the capacitive load is preferably an electrostatic ultrasonic transducer with multiple sound transmission channels. After voltage correction by the correction circuit of this invention, the driving voltage of each sound transmission channel is made the same. In other alternative embodiments, the capacitive load can also be replaced with a resistive load.

[0038] The advantages of this invention are as follows: 1. By adding a voltage correction circuit, this invention processes the AC signal at the output of the load drive circuit to obtain the corresponding voltage value. Based on this voltage value, the drive voltage of the capacitive load is adjusted, ensuring that the drive voltage output to each channel of the capacitive load is consistent or nearly consistent. This improves the listening experience of audio signals played by the capacitive load and achieves automatic calibration of the drive voltage of the multi-channel capacitive load. 2. The voltage correction circuit added in this invention has a simple structure, accurate and effective voltage feedback, and high testing efficiency.

[0039] The foregoing description of specific exemplary embodiments of the present invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the present invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the present invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the present invention, as well as various different choices and variations. The scope of the present invention is intended to be defined by the claims and their equivalents.

Claims

1. A capacitive load voltage correction circuit, characterized in that, The circuit includes: A load driving circuit, the output of which is connected to the capacitive load, and which includes at least a signal processing unit and a power amplifier connected to the signal processing unit. The signal processing unit is used to process the audio signal and amplify it by the power amplifier to output an actual AC signal for driving the capacitive load. The voltage correction circuit includes at least a DC blocking voltage divider circuit, a DC bias circuit, and a microcontroller unit. The DC blocking voltage divider circuit is connected to the power amplifier and is used to block and step down the actual AC signal. The DC bias circuit is connected to the DC blocking voltage divider circuit and is used to apply a DC bias voltage to the stepped-down actual AC signal. The microcontroller unit is connected to the DC bias circuit and a signal processing unit and is used to calculate the voltage value corresponding to the actual AC signal based on the applied DC bias voltage. It then compares the voltage value with a preset voltage and determines whether the error between the two is within a preset error range. If the error is not within the error range, the signal processing unit is fed back to adjust the voltage magnitude of the actual AC signal through gain setting to calibrate it to the driving voltage required to drive the capacitive load.

2. The capacitive load voltage correction circuit as described in claim 1, characterized in that, The voltage correction circuit further includes a rectifier circuit, which is connected to the DC bias circuit and is used to convert the actual AC signal after applying a DC bias voltage into a stable DC signal; and the microcontroller unit is connected to the rectifier circuit and is used to calculate the voltage value corresponding to the DC signal.

3. The capacitive load voltage correction circuit as described in claim 1, characterized in that, The DC blocking voltage divider circuit specifically includes a first DC blocking capacitor, a first voltage divider resistor, and a second voltage divider resistor. One end of the first DC blocking capacitor is connected to the power amplifier, and the other end is connected to one end of the first voltage divider resistor. The other end of the first voltage divider resistor is connected to one end of the second voltage divider resistor, and the other end of the second voltage divider resistor is grounded.

4. A capacitive load voltage correction circuit as described in any one of claims 1 to 3, characterized in that, A second DC blocking capacitor is also connected between the DC blocking voltage divider circuit and the DC bias circuit.

5. The capacitive load voltage correction circuit as described in claim 2, characterized in that, The DC bias circuit includes a third voltage divider resistor and a fourth voltage divider resistor. One end of the third voltage divider resistor is connected to a DC power supply, and the other end is connected between the first voltage divider resistor and the second voltage divider resistor, as well as one end of the fourth voltage divider resistor. The other end of the fourth voltage divider resistor is grounded.

6. The capacitive load voltage correction circuit as described in claim 5, characterized in that, The rectifier circuit includes a rectifier diode and an integrator circuit. The integrator circuit includes a load resistor and a filter capacitor connected in parallel. The positive terminal of the rectifier diode is connected between the third and fourth voltage divider resistors, and the negative terminal is connected to one end of the load resistor. The other end of the load resistor is connected to the microcontroller unit. One end of the filter capacitor is connected between the load resistor and the microcontroller unit, and the other end is grounded.

7. A capacitive load voltage correction circuit as described in claim 6, characterized in that, The voltage correction circuit also includes a discharge circuit connected to the rectifier circuit. The discharge circuit includes a fast discharge resistor connected in parallel with the filter capacitor.

8. A capacitive load voltage correction circuit as described in claim 2, characterized in that, The microcontroller unit includes an analog-to-digital conversion unit, a filtering unit, and a voltage calculation unit. The analog-to-digital conversion unit is connected to the DC bias circuit or the rectifier circuit and is used to sample the received signal and convert it into binary code. The filtering unit is connected to the analog-to-digital conversion unit and is used to filter the digital signal; the voltage calculation unit is connected to the filtering unit and is used to calculate the voltage of the filtered digital signal to obtain the voltage value corresponding to the actual AC signal.

9. A capacitive load voltage correction circuit as described in claim 1, characterized in that, The capacitive load is an electrostatic ultrasonic transducer with multiple sound-emitting channels. After voltage correction by the correction circuit, the driving voltage of each sound-emitting channel is the same.

10. A capacitive load voltage correction circuit as described in claim 1, characterized in that, A DC bias voltage generating circuit is also connected between the output terminal of the load drive circuit and the capacitive load.

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