High-precision measurement circuit and measurement method for jaundice radiation light source driving current

Abstract

The invention discloses a high-precision measurement circuit and a high-precision measurement method for jaundice radiation light source driving current, which are used for measuring the driving current of a light source driving current loop. The circuit is characterized in that the circuit comprises a diverter Rsh, a differential amplifier AMP, a proportional amplification circuit, a DC bias circuit and a microprocessor control module; the diverter Rsh is connected in series in a light source driving current loop; the non-inverting input end and the inverting input end of the differential amplifier AMP are connected with the two ends of the shunt Rsh, the output end of the differential amplifier AMP is connected with the non-inverting input end of the proportional amplification circuit, and the output end of the proportional amplification circuit is connected with the input end of the direct current bias circuit; the input end of the microprocessor control module is connected with the output end of the direct current bias circuit, and the output end of the microprocessor control module is connected with the proportional amplification circuit. According to the invention, the optimal amplification factor can be selected according to different driving currents, and high-resolution and high-precision measurement of the driving current of the radiation light source is realized.

Description

Technical Field

[0001] The invention relates to the field of medical electronics, and in particular to a high-precision measurement circuit and a measurement method for a jaundice radiation light source driving current. Background Art

[0002] At present, hospitals generally use radiation light sources in neonatal jaundice radiation beds for neonatal jaundice treatment. The treatment effect of neonatal jaundice is closely related to parameters such as the wavelength of the radiation light, the intensity of the radiation light, the angle between the radiation light and the newborn, and the illumination time of the radiation light. Doctors optimize and control the above parameters of the radiation light source according to changes in the condition to achieve the best treatment effect. High-precision control of the radiation light angle and illumination time in the above parameters is relatively easy to achieve. However, the wavelength and intensity of the radiation light are determined by the driving current flowing through the light source. The accuracy and stability of the driving current are directly related to the accuracy and stability of the wavelength and light intensity. Therefore, it is necessary to control the driving current of the radiation light source with high precision.

[0003] Neonatal jaundice treatment requires dynamic adjustment of the intensity of the radiation light source and ensures stability under different light intensities, which puts higher requirements on the control of the driving current of the radiation light source, and then puts higher requirements on the measurement circuit of the driving current, that is, it is necessary to take into account the current range and high resolution. On the one hand, when the radiation light source for jaundice treatment works at a weaker light intensity, its driving current value is small. At the same time, in order to ensure the stability of light, the driving current variation range is very narrow. In order to achieve high-resolution measurement of small current values, a large amplification factor is required to increase the variation range of the driving current, reduce the influence of quantization error, electromagnetic interference and noise of AD sampling on current measurement, and achieve high-resolution measurement of small currents. On the other hand, when the radiation light source for jaundice treatment works at a stronger light intensity, its driving current value is larger and the current working range is not very narrow. Compared with the small current situation, only a lower amplification factor is required to achieve high-resolution measurement. However, the commonly used current measurement scheme is incapable of high-resolution measurement of the driving current of the radiation light source for jaundice treatment. When measuring a small current with a very narrow variation range, the voltage signal obtained after the bias, amplification and filtering of the signal conditioning circuit has a very narrow variation range. The AD sampling quantization error and interference have a great influence on the current sampling accuracy, resulting in a large current error. When measuring a larger current with a not very narrow variation range, the voltage signal obtained after amplification exceeds the linear amplification range of the op amp or exceeds the optimal AD sampling range, which also greatly reduces the accuracy of the current measurement. Summary of the invention

[0004] The purpose of the present invention is to provide a high-precision measurement circuit and method for the driving current of a jaundice radiation light source. The present invention can select the optimal amplification factor according to driving currents of different sizes, and achieve high-resolution and high-precision measurement of the driving current of the radiation light source.

[0005] The technical solution of the present invention is a high-precision measurement circuit for the driving current of a jaundice radiation light source, which is used for measuring the driving current of a light source driving current loop. Figure 1 As shown, including the shunt R sh , differential amplifier AMP, proportional amplifier circuit, DC bias circuit and microprocessor control module; the shunt R sh The differential amplifier AMP has a positive input terminal and a negative input terminal connected in series with the shunt R sh The two ends of the differential amplifier AMP are connected, the output end of the differential amplifier AMP is connected to the in-phase input end of the proportional amplifier circuit, and the output end of the proportional amplifier circuit is connected to the input end of the DC bias circuit; the input end of the microprocessor control module is connected to the output end of the DC bias circuit, and the output end of the microprocessor control module is connected to the proportional amplifier circuit.

[0006] The high-precision measurement circuit of the driving current of the jaundice radiation light source mentioned above, the proportional amplification circuit includes an operational amplifier OP1, a resistor R kF , multiple proportional adjustment resistors R kM And multiple proportional regulation NMOS tube Q M The in-phase input terminal of the operational amplifier OP1 is connected to the output terminal of the differential amplifier AMP; the resistor R kF connected between the output terminal and the inverting input terminal of the operational amplifier OP1; the proportional adjustment resistor R kM One end is connected to the inverting input terminal of the operational amplifier OP1, and the proportional adjustment resistor R kM The other end is connected to the proportional regulation NMOS tube Q M The drain of the proportional adjustment NMOS tube Q M The source of the NMOS tube is grounded, and the proportional adjustment NMOS tube Q M The gate is connected to the microprocessor control module.

[0007] The high-precision measurement circuit of the driving current of the jaundice radiation light source mentioned above, the DC bias circuit includes a resistor R 1 , resistor R 2 , resistor R 3 , resistor R 4 and operational amplifier OP2; the resistor R 1 connected between the output terminal of the operational amplifier OP1 and the non-inverting input terminal of the operational amplifier OP2; the resistor R 2connected between the inverting input terminals of the operational amplifier OP2; the resistor R 3 One end is connected to the same-direction input terminal of operational amplifier OP2, and the resistor R 3 The other end is connected to the reference voltage V ref Connect the resistor R 4 Connected between the output terminal and the inverting input terminal of the operational amplifier OP2; the output terminal of the operational amplifier OP2 is connected to the input terminal of the microprocessor control module.

[0008] The aforementioned high-precision measurement circuit of the driving current of the jaundice radiation light source, the microprocessor control module includes a microprocessor MCU and a filter circuit; the input end of the filter circuit is connected to the output end of the operational amplifier OP2, and the output end of the filter circuit is connected to the input end of the microprocessor MCU; the microprocessor MCU is provided with a plurality of NMOS tubes Q M I / O_M port of the gate.

[0009] The measuring method of the high-precision measuring circuit of the aforementioned jaundice radiation light source driving current, the shunt R sh Convert the driving current i of the light source driving current loop into a voltage signal v i ; The differential amplifier AMP converts the voltage signal v i Perform differential amplification to obtain the voltage signal v o1 The proportional amplifier circuit amplifies the voltage signal v according to the initial amplification factor o1 Further amplified into a voltage signal v o The DC bias circuit is for the voltage signal v o Biasing to obtain voltage signal V ref +v o ; The filter circuit filters out the voltage signal V ref +v o The high-frequency interference gets the sampling voltage v samp ; The microprocessor MCU is used for v samp The value of the driving current i is sampled and calculated, and the amplification factor of the proportional amplifier circuit is controlled according to the size of the driving current i.

[0010] The aforementioned high-precision measurement circuit for measuring the driving current of the jaundice radiation light source, wherein the microprocessor MCU controls the NMOS tube Q of the proportional amplifier circuit according to the size of the driving current i. M The switch state can select different resistance values ​​to adjust the resistor R kM .

[0011] Compared with the prior art, the high-precision measurement circuit and method for the driving current of a jaundice radiation light source provided by the present invention can select the optimal amplification factor according to driving currents of different sizes, select a larger amplification factor when the current is small, and select a smaller amplification factor when the current is large, thereby achieving high-resolution and high-precision measurement of the driving current of the radiation light source and improving the treatment effect of neonatal jaundice. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a circuit diagram of the present invention;

[0013] Figure 2 It is a control flow diagram of the sampling and range control module of the present invention. DETAILED DESCRIPTION

[0014] The present invention is further described below in conjunction with the embodiments and drawings, but they are not intended to limit the present invention.

[0015] Embodiment: A high-precision measurement circuit for the driving current of a jaundice radiation light source, as shown in the attached Figure 1 As shown, including the shunt R sh , differential amplifier AMP, proportional amplifier circuit, DC bias circuit and microprocessor control module.

[0016] Shunt R sh Connected in series in the light source driving current loop, it converts the driving current i into a voltage signal v i In order to suppress the temperature change of the shunt R sh The influence of resistance value and measurement accuracy, shunt R sh Choose a smaller resistance. Therefore, the shunt R sh The voltage signal v across the two ends i Very small. Voltage signal v i The driving current i satisfies the following formula:

[0017] v i =R sh ×i;

[0018] The non-inverting input and the inverting input of the differential amplifier AMP are connected to the shunt R sh The two ends of the differential amplifier AMP will shunt R sh The weak voltage signal v at both ends i Perform differential amplification to obtain the amplified voltage signal v o1 The output of the differential amplifier AMP is connected to the non-inverting input of the proportional amplifier circuit. The differential amplifier AMP mainly plays two roles: 1. Suppressing the shunt R sh The common mode interference and noise of the voltage signal on the upper side; 2. The output voltage signal v of the differential amplifier AMP o1It has a strong output current capability and improves the load capacity. Voltage signal v o1 With the voltage signal v i Satisfies the following formula:

[0019] v o1 =K D ×v i ;

[0020] Where: K D is the amplification factor of the differential amplifier AMP;

[0021] The proportional amplifier circuit is used to amplify the output voltage signal v of the differential amplifier AMP. o1 Amplify and select the appropriate amplification factor according to the size of the radiation light source driving current i to ensure high-resolution measurement of the driving current i. The proportional amplifier circuit includes an operational amplifier OP1, a resistor R kF , multiple proportional adjustment resistors R kM And multiple proportional regulation NMOS tube Q M The non-inverting input terminal of the operational amplifier OP1 is connected to the output terminal of the differential amplifier AMP. kF Connected between the output terminal and the inverting input terminal of the operational amplifier OP1, the voltage signal v of the differential amplifier AMP is realized. o1 Perform in-phase amplification with different coefficients. Proportional adjustment resistor R kM One end is connected to the inverting input terminal of the operational amplifier OP1, and the proportional adjustment resistor R kM The other end is connected to the proportional regulation NMOS tube Q M The drain of the proportional control NMOS tube Q M The source of the NMOS tube is grounded, and the proportional adjustment NMOS tube Q M The gate is connected to the microprocessor control module.

[0022] The voltage signal v of the operational amplifier OP1 o With the voltage signal v o1 Satisfies the following formula:

[0023] v o =A k ×v o1 ;

[0024] Among them: A k A is the amplification factor of the proportional amplifier circuit, k = 1, 2, ..., M. k Make the following provisions: When the ratio of the NMOS tube Q M When conducting, there are:

[0025]

[0026] Reasonable choice of RkF With R k1 , R k2 ,……,R kM The relationship between the two can be used to obtain different magnifications. For example: R kF =(10 M -1)R kM , and so on, we can get the magnification A k 10 in sequence k .

[0027] The DC bias circuit includes resistor R 1 , resistor R 2 , resistor R 3 , resistor R 4 and operational amplifier OP2. Resistor R 1 Connected between the output terminal of operational amplifier OP1 and the non-inverting input terminal of operational amplifier OP2, resistor R 2 connected between the inverting input terminals of the operational amplifier OP2; the resistor R 3 One end is connected to the same-direction input terminal of operational amplifier OP2, and the resistor R 3 The other end is connected to the reference voltage V ref Connection, resistor R 4 It is connected between the output terminal and the inverting input terminal of the operational amplifier OP2. The output terminal of the operational amplifier OP2 is connected to the input terminal of the microprocessor control module.

[0028] The function of the DC bias circuit is to convert the voltage signal v o Bias a suitable reference voltage V ref , and get the voltage signal V ref +v o .

[0029] The microprocessor control module includes a microprocessor MCU and a filter circuit; the microprocessor MCU has an AD sampling port and an I / O_M port. The input end of the filter circuit is connected to the output end of the operational amplifier OP2, and the output end of the filter circuit is connected to the input end of the microprocessor MCU; the microprocessor MCU is provided with a plurality of NMOS tubes Q M The I / O_M port of the gate. The voltage signal input to the filter circuit is V ref +v o , by filtering out the voltage signal V ref +v o The high-frequency interference gets the sampling voltage v samp , and the sampled voltage v samp Output to the AD port of the microprocessor MCU. The microprocessor MCU samples the v samp , the value of the driving current i is obtained through calculation, and the calculation process of the microprocessor MCU is as follows Figure 2 As shown. The state of the I / O_M port is determined according to the size of the driving current i, and then the NMOS tube Q is controlled. M The switching state of the sensor is adjusted to adjust the amplification factor of the proportional amplifier circuit to achieve high-precision measurement of the driving current of the jaundice radiation light source.

[0030] A method for measuring a high-precision measurement circuit of a jaundice radiation light source driving current, wherein the shunt R sh Convert the driving current i of the light source driving current loop into a voltage signal v i The differential amplifier AMP converts the voltage signal v i Perform differential amplification to obtain the voltage signal v o1 The proportional amplifier circuit amplifies the voltage signal v according to the initial amplification factor o1 Further amplified into a voltage signal v o The DC bias circuit is for the voltage signal v o Biasing to obtain voltage signal V ref +v o ; The filter circuit filters out the voltage signal V ref +v o The high-frequency interference gets the sampling voltage v samp ; The microprocessor MCU is used for v samp The sampling is performed to calculate the value of the driving current i, and the NMOS tube Q of the proportional amplifier circuit is controlled according to the size of the driving current i. M The switch state can select different resistance values ​​to adjust the resistor R kM , thereby controlling the amplification factor of the amplifier circuit.

[0031] The current high-precision measurement circuit proposed by the present invention is connected to the jaundice radiation light source driving circuit and starts working. The microprocessor MCU initializes all I / O_M ports to low level and all NMOS tubes Q M Close, resistor R kM Neither is connected to the proportional amplifier circuit, the voltage signal v o With the voltage signal v o1 Satisfaction: v o =v o1 . And because v o1 =K D ×R sh ×i, so we have: v o =K D ×R sh ×i. The present invention uses a 1mΩ shunt R sh , the gain K of the differential amplifier AMP D is 10, so we have: o =0.01i. The proportional amplifier circuit is used to measure the voltage signal vo Bias reference voltage V ref , get the sampling signal V ref +0.01i. Reference voltage V ref Can be generated by a high-precision voltage reference source chip, the reference voltage V ref The specific value and voltage reference source chip model can be determined by the microprocessor MCU chip parameters. The present invention tentatively sets V ref =1.024V. Sampling signal V ref +0.01i is filtered out through the filter circuit to remove high-frequency interference and obtain the sampling signal v samp After that, the microprocessor MCU samples the signal v samp Sampling is performed and according to the formula v samp =1.024+0.01i to calculate the size of the driving current i. The MCU obtains the optimal amplification factor corresponding to I by looking up the table, and then controls the corresponding NMOS tube Q M Therefore, when the driving current i is very small, a resistor corresponding to a larger amplification factor is selected, for example, a resistor R k3 The amplification resistor is amplified 1000 times to achieve high-precision detection of tiny currents. When the drive current i is large, a resistor with a smaller amplification factor should be selected. The resistor R k1 To amplify the resistor, a 10-fold amplification is achieved. When the current is large, all I / O_M ports are controlled to be low level, and all NMOS tubes Q M Close, the magnification of the proportional amplifier circuit is 1, which can prevent the sampling voltage v from being too high due to excessive magnification on the basis of high-precision detection of current. samp Exceeded sampling range.

[0032] In summary, the present invention can select the optimal amplification factor according to driving currents of different sizes, thereby achieving high-resolution and high-precision measurement of the driving current of the radiation light source.

Claims

1. A high-precision measurement circuit for the driving current of a jaundice radiation light source, used for measuring the driving current of a light source driving current loop; characterized in that: Including shunt R sh , differential amplifier AMP, proportional amplifier circuit, DC bias circuit and microprocessor control module; the shunt R sh The differential amplifier AMP has a positive input terminal and a negative input terminal connected in series with the shunt R sh The two ends of the differential amplifier AMP are connected, the output end of the differential amplifier AMP is connected to the in-phase input end of the proportional amplifier circuit, and the output end of the proportional amplifier circuit is connected to the input end of the DC bias circuit; the input end of the microprocessor control module is connected to the output end of the DC bias circuit, and the output end of the microprocessor control module is connected to the proportional amplifier circuit.

2. The high-precision measurement circuit for driving current of a jaundice radiation light source according to claim 1, characterized in that: The proportional amplifier circuit includes an operational amplifier OP1, a resistor R kF , multiple proportional adjustment resistors R kM And multiple proportional regulation NMOS tube Q M The in-phase input terminal of the operational amplifier OP1 is connected to the output terminal of the differential amplifier AMP; the resistor R kF connected between the output terminal and the inverting input terminal of the operational amplifier OP1; The proportional adjustment resistor R kM One end is connected to the inverting input terminal of the operational amplifier OP1, and the proportional adjustment resistor R kM The other end is connected to the proportional regulation NMOS tube Q M The drain of the proportional adjustment NMOS tube Q M The source of the NMOS tube is grounded, and the proportional adjustment NMOS tube Q M The gate is connected to the microprocessor control module.

3. The high-precision measurement circuit for driving current of a jaundice radiation light source according to claim 2, characterized in that: The DC bias circuit includes a resistor R1, a resistor R2, a resistor R3, a resistor R4 and an operational amplifier OP2; the resistor R1 is connected between the output end of the operational amplifier OP1 and the non-inverting input end of the operational amplifier OP2; the resistor R2 is connected between the reverse input ends of the operational amplifier OP2; one end of the resistor R3 is connected to the non-inverting input end of the operational amplifier OP2, and the other end of the resistor R3 is connected to the reference voltage V ref The resistor R4 is connected between the output terminal and the reverse input terminal of the operational amplifier OP2; the output terminal of the operational amplifier OP2 is connected to the input terminal of the microprocessor control module.

4. The high-precision measurement circuit for driving current of a jaundice radiation light source according to claim 3, characterized in that: The microprocessor control module includes a microprocessor MCU and a filter circuit; the input end of the filter circuit is connected to the output end of the operational amplifier OP2, and the output end of the filter circuit is connected to the input end of the microprocessor MCU; the microprocessor MCU is provided with a plurality of NMOS transistors Q M I / O_M port of the gate.

5. The method for measuring the high-precision measurement circuit of the driving current of the jaundice radiation light source according to any one of claims 1 to 4, characterized in that: The shunt R sh Convert the driving current i of the light source driving current loop into a voltage signal v i The differential amplifier AMP converts the voltage signal v i Perform differential amplification to obtain the voltage signal v o1 The proportional amplifier circuit amplifies the voltage signal v according to the initial amplification factor o1 Further amplified into a voltage signal v o The DC bias circuit is for the voltage signal v o Biasing to obtain voltage signal v ref +v o ; The filter circuit filters out the voltage signal V ref +v o The high-frequency interference gets the sampling voltage v samp ; The microprocessor MCU is used for v samp The value of the driving current i is sampled and calculated, and the amplification factor of the proportional amplifier circuit is controlled according to the size of the driving current i.

6. The method for measuring the high-precision measurement circuit of the jaundice radiation light source driving current according to claim 5, characterized in that: The microprocessor MCU controls the NMOS tube Q of the proportional amplifier circuit according to the size of the driving current i. M The switch state can select different resistance values ​​to adjust the resistor R kM .

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