Multi-stage amplification circuit for eye electromyogram signal detection

Abstract

The utility model belongs to the field of biomedical signal detection and electronic circuits, and particularly relates to a multistage amplification circuit for eye electromyographic signal detection, which comprises an input signal processing circuit, a primary amplification circuit and a secondary amplification circuit. According to the utility model, the input signal processing circuit, the primary amplification circuit and the secondary amplification circuit are arranged, so that multi-stage high-gain amplification is realized, the detection precision of eye electromyographic signals is effectively improved, and the eye electromyographic signal detection circuit is suitable for detecting weak eye electromyographic signals; by arranging low-pass filter capacitors C1, C2 and C41 and providing reference voltage, interference of external high-frequency noise and power supply fluctuation on the eye electromyographic signals is reduced, and the accuracy and reliability of eye electromyographic signal measurement are ensured.

Description

TECHNICAL FIELD

[0001] The utility model relates to belong to biomedical signal detection and electronic circuit field, concretely relates to a kind of multistage amplification circuit for ocular muscle electric signal detection, for detecting and amplifying ocular muscle electric signal, it is suitable for use in biomedical, ophthalmic diagnosis, eyeball movement analysis etc. BACKGROUND

[0002] Current ocular muscle electric (EOG) signal measurement is widely used in eyeball movement detection, visual line tracking and ophthalmic diagnosis fields. Ocular muscle electric signal is a kind of weak bioelectric signal, which is usually susceptible to external noise interference, and has low signal amplitude and low frequency, which puts high requirements on signal amplification and noise suppression. Traditional amplification circuit is difficult to meet the requirements of high gain, low noise and high stability at the same time, so the existing equipment has great limitations in measurement accuracy and anti-interference performance.

[0003] In order to improve the accuracy of ocular muscle electric signal measurement, single-stage amplification circuit or simple passive filter is usually used for amplification and filtering in the prior art, but when facing weak and low-frequency ocular muscle electric signal, such circuit often cannot provide sufficient gain and signal-to-noise ratio. UTILITY MODEL CONTENTS

[0004] The utility model aims at solving the technical problems in the background art, and provides a multistage amplification circuit for ocular muscle electric signal detection.

[0005] In order to achieve the above-mentioned purpose, the utility model adopts the following technical scheme:

[0006] A multistage amplification circuit for ocular muscle electric signal detection, comprising an input signal processing circuit, a primary amplification circuit and a secondary amplification circuit.

[0007] The input signal processing circuit comprises diodes VD1 and VD2, resistors R1 and R2.

[0008] The primary amplification circuit comprises a differential amplifier U4.

[0009] The secondary amplification circuit comprises an operational amplifier U1.

[0010] Among them, diodes VD1 and VD2 are connected in reverse parallel between input terminal one and input terminal two, resistor R1 is connected between one end of diode VD2 and pin 2 of differential amplifier U4, resistor R2 is connected between the other end of diode VD2 and pin 3 of differential amplifier U4, resistors R5 and R6 are connected in series between pin 1 and pin 8 of differential amplifier U4, and gain adjusting resistor is connected outside between resistors R5 and R6.

[0011] A resistor R9 is connected between pin 6 of the differential amplifier U4 and pin 2 of the operational amplifier U1, and a resistor R10 is connected between pin 1 and pin 2 of the operational amplifier U1.

[0012] The input signal processing circuit further comprises bypass capacitors C1 and C2.

[0013] One end of the bypass capacitor C1 is connected to a line between the resistor R1 and pin 2 of the differential amplifier U4, and the other end of the bypass capacitor C1 is grounded.

[0014] One end of the bypass capacitor C2 is connected to a line between the resistor R2 and pin 3 of the differential amplifier U4, and the other end of the bypass capacitor C2 is grounded.

[0015] Pin 2 and pin 3 of the differential amplifier U4 are connected to a capacitor C4.

[0016] Pin 7 of the differential amplifier U4 is connected to a power supply voltage, and the power supply voltage is grounded through the parallel connection of capacitors C5 and C30.

[0017] Pin 3 and pin 5 of the operational amplifier U1 are connected to a reference voltage.

[0018] Pin 8 of the operational amplifier U1 is connected to a power supply voltage, and the power supply voltage is grounded through a capacitor C12.

[0019] A capacitor C41 is connected in parallel to the resistor R10.

[0020] Compared with the prior art, the utility model has the following technical effects:

[0021] The utility model discloses an input signal processing circuit, a primary amplification circuit and a secondary amplification circuit are arranged, realize multistage high gain amplification, improve the detection precision of eye muscle electricity signal effectively, be applicable to weak eye muscle electricity signal's detection, through setting low pass filter capacitor C1, C2, C41 and providing reference voltage, reduce the interference of high frequency noise and power supply fluctuation of outside to eye muscle electricity signal, ensure the precision and reliability of eye muscle electricity signal measurement.

[0022] The utility model is further illustrated below in connection with the drawings and examples. DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments or the prior art. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0024] Figure 1 is the connection relationship diagram of the input signal processing circuit in the present application;

[0025] Figure 2 is the connection relationship diagram of the primary amplification circuit in the present application;

[0026] Figure 3 is the connection relationship diagram of the secondary amplification circuit in the present application. DETAILED DESCRIPTION

[0027] In order to make the above-mentioned purposes, features and advantages of the present application more apparent, specific embodiments of the present application will be described in detail below with reference to the drawings. In the following description, many specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0028] As shown in Figures 1-3 , the present embodiment provides a multi-stage amplification circuit for detecting eye muscle electrical signals, which comprises an input signal processing circuit, a primary amplification circuit and a secondary amplification circuit.

[0029] 1. Input signal processing circuit

[0030] As shown in Figure 1 , the input signal processing circuit is composed of diodes VD1, VD2, resistors R1, R2, capacitors C1, C2, C4, etc.

[0031] Among them, diodes VD1 and VD2 are input protection diodes, which are connected in reverse parallel between the "Right1" input end and the "Left1" input end. When the input signal is too high, diodes VD1 and VD2 will be turned on, thereby limiting the input voltage and protecting the amplifier at the back end from overvoltage impact.

[0032] Resistors R1 and R2 are input resistors, which are connected in series in the input signal path, used to limit the input current and realize impedance matching, preventing the signal source from being affected by the load.

[0033] Capacitors C1 and C2 are used as bypass capacitors, connected in parallel between the input terminal and ground to filter out high-frequency noise and ensure the purity of the amplifier's input signal, making them suitable for low-frequency signal processing.

[0034] 2. Primary amplifier circuit

[0035] like Figure 2 As shown, the primary amplifier circuit consists of a differential amplifier U4, resistors R5 and R6, and capacitors C5 and C30.

[0036] The differential amplifier U4 uses an INA326, with pins 1-8 being R1, VIN-, VIN+, VDD- / GND, R2, V0, VDD+, and R1, respectively. Differential amplifier U4 is configured with a gain of 5 to amplify weak electromyography (EMG) differential signals and suppress common-mode noise. The gain is determined by the external resistor (not shown, defaulting to a gain of 5) between pins 1 and 8 of differential amplifier U4.

[0037] 3. Two-stage amplifier circuit

[0038] like Figure 3 As shown, the two-stage amplifier circuit consists of operational amplifier U1, resistors R9 and R10, capacitors C12 and C41, etc.

[0039] Operational amplifier U1 uses an ADS872 microcontroller, with pins 1-8 designated as OUTA, -INA, +INA, VDD- / GND, +INB, -INB, OUTB, and VDD+, respectively. Operational amplifier U1 achieves a high gain of 400x. Gain control is implemented through feedback resistor R10 and input resistor R9, further amplifying the signal from the primary amplifier circuit to a measurable level. Pins 3 and 5 of operational amplifier U1 are connected to a reference voltage. The filter capacitor C41 and feedback resistor R10 are used in combination to stabilize the high-gain amplifier U1 and prevent high-frequency noise and signal self-oscillation.

[0040] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model in any way. Any person skilled in the art can make many possible variations and modifications to the technical solution of this utility model using the disclosed methods and techniques, or modify it into equivalent embodiments with equivalent changes, without departing from the scope of the technical solution of this utility model. Therefore, all equivalent changes made based on the shape, structure, and principle of this utility model without departing from its technical solution should be covered within the protection scope of this utility model.

Claims

1. A multi-stage amplification circuit for detecting electromyographic signals of the eye, characterized in that, It includes an input signal processing circuit, a primary amplifier circuit, and a secondary amplifier circuit; The input signal processing circuit includes diodes VD1 and VD2, and resistors R1 and R2; The primary amplifier circuit includes a differential amplifier U4; The secondary amplifier circuit includes operational amplifier U1; In this configuration, diodes VD1 and VD2 are connected in reverse parallel between input terminal 1 and input terminal 2. A resistor R1 is connected between one end of diode VD2 and pin 2 of differential amplifier U4, and a resistor R2 is connected between the other end of diode VD2 and pin 3 of differential amplifier U4. Resistors R5 and R6 are connected in series between pin 1 and pin 8 of differential amplifier U4, and an external gain adjustment resistor is connected between resistors R5 and R6. A resistor R9 is connected between pin 6 of differential amplifier U4 and pin 2 of operational amplifier U1, and a resistor R10 is connected between pin 1 and pin 2 of operational amplifier U1.

2. The multi-stage amplification circuit for detecting electromyographic signals of the eye as described in claim 1, characterized in that, The input signal processing circuit also includes bypass capacitors C1 and C2; One end of the bypass capacitor C1 is connected to the line between resistor R1 and pin 2 of differential amplifier U4, and the other end of the bypass capacitor C1 is grounded. One end of the bypass capacitor C2 is connected to the line between resistor R2 and pin 3 of differential amplifier U4, and the other end of the bypass capacitor C2 is grounded.

3. The multi-stage amplification circuit for detecting electromyographic signals of the eye as described in claim 1, characterized in that, A capacitor C4 is connected between pin 2 and pin 3 of the differential amplifier U4.

4. The multi-stage amplification circuit for detecting electromyographic signals of the eye as described in claim 1, characterized in that, Pin 7 of the differential amplifier U4 is connected to the power supply voltage, which is grounded through parallel capacitors C5 and C30.

5. The multi-stage amplification circuit for detecting electromyographic signals of the eye as described in claim 1, characterized in that, Pins 3 and 5 of the operational amplifier U1 are both connected to a reference voltage.

6. The multi-stage amplification circuit for detecting electromyographic signals of the eye as described in claim 1, characterized in that, Pin 8 of the operational amplifier U1 is connected to the power supply voltage, which is grounded through capacitor C12.

7. The multi-stage amplification circuit for detecting electromyographic signals of the eye as described in claim 1, characterized in that, A capacitor C41 is connected in parallel across the two ends of the resistor R10.

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