An ultrasonic transducer drive circuit and electronic artificial larynx

Abstract

The application discloses an ultrasonic transducer driving circuit and an electronic artificial larynx, and relates to the field of medical devices. In the ultrasonic transducer driving circuit, a power module is used for providing power supply for the whole driving circuit; a glottal wave pulse modulator is used for amplitude modulating a glottal wave signal of normal speech of a patient and a carrier signal for exciting the ultrasonic transducer to generate a modulated signal; a differential output power amplifier is used for signal conditioning and power amplification of the modulated signal, and the amplified driving signal is output in a differential mode; a transformer is used for boosting the amplified driving signal to generate a boosted driving signal; and a matching circuit is used for realizing impedance matching between the boosted driving signal and the ultrasonic transducer, so that the power of the boosted driving signal is maximized and loaded on the ultrasonic transducer to drive the ultrasonic transducer to emit ultrasonic waves. The ultrasonic transducer driving circuit can reduce the overall volume of the driving circuit and meet the portable requirement of a handheld electronic artificial larynx device.

Description

Technical Field

[0001] This application relates to the field of medical device technology, and in particular to an ultrasonic transducer drive circuit and an electronic artificial larynx. Background Technology

[0002] Electronic larynxes are commonly used to provide an external sound source for laryngeal cancer patients after laryngectomy. The external sound source is transmitted through the neck tissue to the patient's vocal tract and modulated into speech. Traditional electronic larynxes use an armature motor as the sound source, but this source generates strong radiated noise. To address this, a novel electronic larynx based on acoustic parametric array technology has been proposed, such as a pathological speech aid system based on acoustic parametric array technology, which can overcome the radiated noise problem of electronic larynxes using armature motors as the sound source. This type of electronic larynx based on acoustic parametric array technology uses an ultrasonic transducer as the excitation sound source. Because the efficiency of ultrasonic waves in generating glottic wave signals through self-demodulation in human tissue is low, ultrasonic transducers require a relatively high-power drive signal. This driver requires a large supply voltage and high output power, resulting in a large overall size. However, electronic larynx devices are handheld, battery-powered devices, requiring a small device size. Therefore, there is an urgent need for miniaturization and portable design of its drive circuitry, enabling this novel electronic larynx to meet the design requirements of handheld devices. Summary of the Invention

[0003] To address the problems existing in the prior art, the purpose of this application is to provide an ultrasonic transducer drive circuit and an electronic artificial larynx, so as to reduce the size of the drive circuit and meet the portability requirements of handheld electronic artificial larynx devices.

[0004] To achieve the above objectives, this application provides the following solution.

[0005] On the one hand, this application provides an ultrasonic transducer drive circuit, including: a power supply module and a glottal pulse modulator, a differential output power amplifier, a transformer and a matching circuit connected in sequence;

[0006] The power module is used to provide power to the entire drive circuit;

[0007] The glottal pulse modulator is used to modulate the glottal wave signal of the patient's normal speech with the carrier signal that excites the ultrasound transducer to generate a modulated signal.

[0008] The differential output power amplifier is used to condition and amplify the modulated signal, and outputs the amplified drive signal in a differential manner.

[0009] The transformer is used to boost the amplified drive signal to generate a boosted drive signal.

[0010] The matching circuit is used to achieve impedance matching between the boosted drive signal and the ultrasonic transducer, so that the power of the boosted drive signal is maximized and applied to the ultrasonic transducer to drive the ultrasonic transducer to emit ultrasonic waves.

[0011] Optionally, the power module is powered by a battery with a voltage range of 3.2V to 5V.

[0012] Optionally, the glottal pulse modulator uses digital modulation technology to perform quadrature amplitude modulation on the carrier signal and the glottal wave signal, and the frequency range of the generated modulation signal is 20kHz to 200kHz.

[0013] Optionally, the glottal pulse modulator uses digital modulation technology to perform quadrature amplitude modulation on the carrier signal and the glottal wave signal, specifically including: performing single-sideband modulation in an MCU, DSP, or FPGA.

[0014] Optionally, the glottal pulse modulator uses digital modulation technology to perform quadrature amplitude modulation on the carrier signal and the glottal wave signal, specifically including: performing double-sideband modulation in an MCU, DSP, or FPGA.

[0015] Optionally, the frequency of the carrier signal is the same as the center frequency of the ultrasonic transducer.

[0016] Optionally, the carrier signal is a sine wave signal.

[0017] Optionally, the differential output power amplifier performs signal conditioning on the modulated signal, including filtering conditioning and amplitude conditioning, and uses differential output after power amplification.

[0018] Optionally, the turns ratio of the primary coil to the secondary coil of the transformer is 1:5 to 1:10.

[0019] On the other hand, this application provides an electronic artificial larynx, which is based on acoustic parametric array technology and uses an ultrasonic transducer as the excitation sound source. The ultrasonic transducer is driven by the ultrasonic transducer driving circuit. The ultrasonic waves emitted by the ultrasonic transducer are self-demodulated into glottic wave signals in the patient's body, enabling the patient to speak normally.

[0020] According to the specific embodiments provided in this application, the following technical effects are disclosed:

[0021] This application provides an ultrasonic transducer drive circuit that uses a glottal pulse modulator to modulate the glottal wave signal of a patient's normal speech with the carrier signal that excites the ultrasonic transducer. The generated modulated signal is then conditioned and amplified by a differential output power amplifier. The amplified drive signal is output differentially, and the excitation transformer boosts the voltage, which then drives the ultrasonic transducer to emit ultrasonic waves. The ultrasonic transducer drive circuit designed in this application is small in size and lightweight, making it particularly suitable for high-power driving of ultrasonic transducers in portable electronic artificial laryngeal devices. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the overall structure of an ultrasonic transducer drive circuit.

[0024] Figure 2 A schematic diagram of amplitude modulation of glottic wave signal and carrier signal;

[0025] Figure 3 Example diagram of glottal wave signal waveform;

[0026] Figure 4 Example diagram of carrier signal waveform;

[0027] Figure 5 This is a basic block diagram of a double-sideband amplitude signal processing method;

[0028] Figure 6 This is a diagram illustrating an example of a modulated signal waveform.

[0029] Figure 7 This is a circuit diagram of a differential output power amplifier, transformer, and ultrasonic transducer. Detailed Implementation

[0030] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] The purpose of this application is to provide an ultrasonic transducer drive circuit and an electronic artificial larynx, which can reduce the size of the drive circuit and meet the portability requirements of handheld electronic artificial larynx devices.

[0032] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] In one exemplary embodiment, this application provides an ultrasonic transducer drive circuit. For example... Figure 1 As shown, the ultrasonic transducer drive circuit includes: a power supply module and a glottal pulse modulator, a differential output power amplifier, a transformer, and a matching circuit connected in sequence.

[0034] The power module provides power to the entire drive circuit. Specifically, the power module is powered by a battery with a voltage range of 3.2V to 5V. In one specific embodiment, the power module uses a 3000mAh 18650 type 3.7V lithium battery with a discharge current of 1C.

[0035] like Figure 2 As shown, the glottal wave pulse modulator is used to amplitude modulate the stored glottal wave signal of the patient's normal speech (original pronunciation) with the carrier signal that excites the ultrasound transducer, generating a modulated signal. Specifically, the glottal wave pulse modulator uses digital modulation technology to perform quadrature amplitude modulation on the carrier signal and the glottal wave signal. For example, single-sideband modulation or double-sideband modulation can be performed in an MCU, DSP, or FPGA. The frequency range of the generated modulated signal is 20kHz to 200kHz. The glottal wave signal is stored in the corresponding MCU, DSP, or FPGA, and the carrier signal is generated by the MCU, DSP, or FPGA.

[0036] The glottal wave signal of the patient's normal speech can originate from the patient's normal speech before the onset of the illness, or from the speech of other normal individuals with similar pronunciation. In one specific embodiment, the glottal wave signal waveform is as follows: Figure 3 As shown, the horizontal axis represents time, and the vertical axis represents the normalized amplitude of voltage.

[0037] The carrier signal has the same frequency as the center frequency of the ultrasonic transducer to drive the transducer to emit ultrasonic waves of the corresponding frequency. In one specific embodiment, the center frequency of the target ultrasonic transducer is 40 kHz. The carrier signal is a sine wave signal with a center frequency of 40 kHz, and its waveform is as follows: Figure 4 As shown, the horizontal axis represents time, and the vertical axis represents the normalized amplitude of voltage.

[0038] In one specific embodiment, the MCU used is an STMicroelectronics STM32G431CBT6 ARM Cortex-M4 MCU with DSP and FPU. The glottal wave signal is stored in the MCU's Flash memory, and the MCU generates a 40kHz sine wave signal as the carrier signal, the waveform of which is as follows. Figure 4 As shown. Using Figure 5 The double-sideband amplitude signal processing method shown modulates the glottal wave signal and the 40kHz sine wave signal. The resulting modulated signal is converted from a digital signal to an analog signal output through the analog-to-digital converter (DAC) of the MCU. Figure 5 The modulation process shown can be described by the following formula:

[0039] y DSB (t)=(mf(t)+1)·cos(ω c t)

[0040] Where f(t) is the glottal wave signal; m represents the modulation depth, ranging from 0 to 1; cos(ω c t) is a center frequency of ω c The carrier signal, ω in this embodiment c 40kHz; y DSB (t) represents the generated modulation signal, and its waveform is as follows: Figure 6 As shown, the horizontal axis represents time, and the vertical axis represents the normalized amplitude of voltage.

[0041] The differential output power amplifier is used to condition and amplify the modulated signal output by the glottal pulse modulator, and outputs the amplified drive signal differentially. Specifically, the signal conditioning performed by the differential output power amplifier on the modulated signal includes filtering conditioning and amplitude conditioning, and the amplified signal is output differentially.

[0042] In one specific embodiment, the circuit connections of the differential output power amplifier, transformer, and ultrasonic transducer are as follows: Figure 7 As shown, the matching circuit is not shown for ease of display. Figure 7 As shown, the differential output power amplifier includes resistors R1 to R3, capacitor C, operational amplifiers U1 and U2, and transistors Q1 to Q4. One end of resistor R1 is connected to the modulation signal y. DSB(t); The other end of resistor R1 is connected to the positive input terminal of operational amplifier U1, one end of resistor R2, and one end of capacitor C. The inverting input terminal of operational amplifier U1 is connected to the output terminal of operational amplifier U1, the base of transistor Q1, and the base of transistor Q2. The collector of transistor Q1 is connected to the power supply voltage V; the emitters of transistor Q1 and Q2 are both connected to one end of the low-voltage side of transformer T; the collector of transistor Q2 is grounded. The positive input terminal of operational amplifier U2 is connected to the power supply voltage V and the other end of capacitor C. The inverting input terminal of operational amplifier U2 is connected to the other end of resistor R2 and one end of resistor R3. The output terminal of operational amplifier U2 is connected to the other end of resistor R3, the base of transistor Q3, and the base of transistor Q4. The collector of transistor Q3 is connected to the power supply voltage V. The emitters of transistors Q3 and Q4 are both connected to the other end of the low-voltage side of transformer T; the collector of transistor Q4 is grounded. The high-voltage side of transformer T is connected in parallel across ultrasonic transducer B.

[0043] like Figure 7 As shown, in this embodiment, a high-pass filter is formed using resistor R1 and capacitor C to filter the modulated signal y output after the previous stage modulation. DSB The low-frequency components of (t) are filtered. Two AD8397 operational amplifiers, U1 and U2, are used to construct non-inverting amplifier circuits with a gain of 1. Figure 1 (represented by G in the text) and an inverting amplifier circuit with a gain of -1 ( Figure 1 (Used as -G in Chinese), the preamplifier signal is converted into a differential output. Each differential output signal is then amplified by a Class AB power amplifier. Each Class AB power amplifier consists of an NPN transistor 2N5550 and a PNP transistor 2N5401, meeting the power output requirements. Specifically, Q1 and Q3 use NPN transistors 2N5550, and Q2 and Q4 use PNP transistors 2N5401. Transistors Q1 and Q2 form the Class AB power amplifier corresponding to operational amplifier U1, and transistors Q3 and Q4 form the Class AB power amplifier corresponding to operational amplifier U2. Resistors R2 and R3 have equal resistance values. Resistor R1 and capacitor C form a high-pass filter. The specific resistance values ​​of resistors R1 to R3 need to be determined based on the center frequency of the modulation signal, and are generally a few ohms. The power supply voltage V is the output voltage of the power module.

[0044] like Figure 7 As shown, the modulated signal y DSB(t) After being filtered by a high-pass filter composed of resistor R1 and capacitor C, the signal enters a 1x gain non-inverting amplifier circuit composed of operational amplifier U1 and a -1x gain inverting amplifier circuit composed of operational amplifier U2, respectively, to enhance the driving capability. Transistors Q1 and Q2, and transistors Q3 and Q4, respectively form Class AB power amplifiers to increase the output power. The amplified drive signal is then stepped up by transformer T to drive the ultrasonic transducer B.

[0045] That is, the transformer T is used to boost the amplified drive signal to generate a boosted drive signal. Specifically, the turns ratio of the primary coil to the secondary coil of the transformer is 1:5 to 1:10.

[0046] In one specific embodiment, the primary and secondary coil turns ratio of the transformer T is 1:10, which can amplify the differential output excitation signal (drive signal) by a factor of 10. The peak-to-peak voltage of the drive signal can reach 70V.

[0047] The matching circuit is used to achieve impedance matching between the boosted drive signal and the ultrasonic transducer, maximizing the power of the boosted drive signal applied to the ultrasonic transducer to drive it to emit ultrasonic waves. The ultrasonic waves emitted by the transducer are self-demodulated into glottic wave signals within the patient's body, enabling the patient to speak normal speech.

[0048] Matching circuits typically consist of a network of resistors, capacitors, and inductors. They are used to match the output impedance of the entire drive circuit with the impedance of the ultrasonic transducer (usually 50 ohms) to optimize power output. The specific design of the matching circuit depends on the impedance of the ultrasonic transducer.

[0049] The aforementioned ultrasonic transducer drive circuit uses a modulated signal obtained by amplitude modulation of a normal speech glottal wave signal and a sinusoidal carrier signal. After filtering and amplitude conditioning, the signal is amplified and output differentially to drive a transformer for voltage boosting. This boosted voltage drives the ultrasonic transducer to emit ultrasonic waves. The ultrasonic waves from the transducer self-demodulate into a glottal wave signal within the patient's body, enabling the patient to produce normal speech. Compared to existing technologies, this application reduces the amplitude requirement of the power supply voltage while outputting a high-power ultrasonic transducer drive signal to drive the ultrasonic transducer to output ultrasonic signals. Therefore, it can significantly reduce the system size and meet the system requirements of handheld acoustic parametric arrays. The ultrasonic transducer drive circuit designed in this application can be battery powered, is compact, and lightweight, making it particularly suitable for high-power driving of ultrasonic transducers in miniaturized portable electronic artificial laryngeal devices.

[0050] Therefore, in an exemplary embodiment, this application also provides an electronic artificial larynx, which may be a pathological speech aid system based on acoustic parametric array technology, using an ultrasonic transducer as the excitation sound source. The ultrasonic transducer employs... Figure 1 The ultrasonic transducer is driven by the circuit shown. The ultrasonic waves emitted by the transducer are demodulated into glottic wave signals within the patient's body, enabling the patient to speak normally.

[0051] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0052] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. An ultrasonic transducer drive circuit, characterized in that, include: The power module and the glottal pulse modulator, differential output power amplifier, transformer and matching circuit connected in sequence; The power module is used to provide power to the entire drive circuit; the power module is powered by a battery with a voltage range of 3.2V to 5V. The glottal pulse modulator is used to modulate the glottal wave signal of the patient's normal speech with the carrier signal that excites the ultrasound transducer to generate a modulated signal. The glottal pulse modulator uses digital modulation technology to perform quadrature amplitude modulation on the carrier signal and the glottal wave signal, including single-sideband modulation or double-sideband modulation in MCU, DSP or FPGA. The frequency range of the modulated signal generated after modulation is 20kHz to 200kHz. The carrier signal has the same frequency as the center frequency of the ultrasonic transducer to drive the ultrasonic transducer to emit ultrasonic waves of the corresponding frequency; the center frequency of the target ultrasonic transducer is 40kHz; the carrier signal is a sine wave signal with a center frequency of 40kHz. The glottal wave signal is stored in the MCU's Flash memory. The MCU generates a 40kHz sine wave signal as the carrier signal. A double-sideband amplitude signal processing method is used to modulate the glottal wave signal and the 40kHz sine wave signal. The resulting modulated signal is converted from a digital signal to an analog signal by the MCU's analog-to-digital converter (DAC). The modulation process is described by the following formula: the DSB (t)=(mf(t)+1)·cos(ω c t) Where f(t) is the glottal wave signal; m represents the modulation depth, ranging from 0 to 1; cos(ω c t) is a center frequency of ω c The carrier signal, ω c 40kHz; y DSB (t) represents the generated modulation signal; The differential output power amplifier is used to condition and amplify the modulated signal, and outputs the amplified drive signal in a differential manner. The signal conditioning of the modulated signal by the differential output power amplifier includes filtering conditioning and amplitude conditioning, and the power amplified signal is output differentially. The differential output power amplifier includes resistors R1 to R3, capacitor C, operational amplifiers U1 and U2, and transistors Q1 to Q4. The transformer is used to boost the amplified drive signal to generate a boosted drive signal. The matching circuit is used to achieve impedance matching between the boosted drive signal and the ultrasonic transducer, so that the power of the boosted drive signal is maximized and applied to the ultrasonic transducer to drive the ultrasonic transducer to emit ultrasonic waves.

2. The ultrasonic transducer drive circuit according to claim 1, characterized in that, The turns ratio of the primary coil to the secondary coil of the transformer is 1:5 to 1:

10.

3. An electronic artificial larynx, based on acoustic parametric array technology, using an ultrasonic transducer as the excitation sound source, characterized in that, The ultrasonic transducer is driven by the ultrasonic transducer driving circuit according to any one of claims 1 to 2; the ultrasonic waves emitted by the ultrasonic transducer are self-demodulated into glottic wave signals in the patient's body, enabling the patient to speak normal speech.

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