阅读说明：本技术 一种组合式相对湿度传感器 (Combined relative humidity sensor ) 是由 何塍兴 于 2020-12-08 设计创作，主要内容包括：本发明公开了一种组合式相对湿度传感器,包括：温度传感器,对环境中的温度进行检测；湿度传感器,对环境中的湿度进行检测；温度运算放大器电路,对所述温度传感器输入的温度值进行转换运算以输出温度当量电压值；湿度运算放大器电路,对所述湿度传感器输入的湿度值进行转换运算以输出湿度当量电压值；相对湿度运算电路,根据所述温度当量电压值以及湿度当量电压值,并利用对数和反对数运算组件计算相对湿度。该组合式相对湿度传感器克服现有技术中的相对湿度传感器存在硬件电路复杂,开发专用的非线性处理软件的周期较长,使构成完整的相对湿度自动化仪表的成本较高,构建与维护系统的周期也较长的问题。(The invention discloses a combined relative humidity sensor, comprising: a temperature sensor that detects a temperature in an environment; a humidity sensor for detecting humidity in the environment; the temperature operational amplifier circuit is used for converting and operating the temperature value input by the temperature sensor to output a temperature equivalent voltage value; the humidity operational amplifier circuit is used for converting and operating the humidity value input by the humidity sensor to output a humidity equivalent voltage value; and the relative humidity computing circuit computes the relative humidity according to the temperature equivalent voltage value and the humidity equivalent voltage value by utilizing a logarithm computing component and an inverse logarithm computing component. The combined relative humidity sensor solves the problems that a relative humidity sensor in the prior art has complex hardware circuit and longer period for developing special nonlinear processing software, so that the cost for forming a complete relative humidity automatic instrument is higher, and the period for constructing and maintaining a system is longer.)

1. A combined relative humidity sensor, comprising:

a temperature sensor that detects a temperature in an environment;

a humidity sensor for detecting humidity in the environment;

the temperature operational amplifier circuit is used for converting and operating the temperature value input by the temperature sensor to output a temperature equivalent voltage value;

the humidity operational amplifier circuit is used for converting and operating the humidity value input by the humidity sensor to output a humidity equivalent voltage value;

and the relative humidity computing circuit computes the relative humidity according to the temperature equivalent voltage value and the humidity equivalent voltage value by utilizing a logarithm computing component and an inverse logarithm computing component.

2. The combined relative humidity sensor of claim 1, wherein the temperature sensor is a platinum thermistor pt 100.

3. Combined relative humidity sensor according to claim 1 or 2,

the basic equation of the input-output characteristic of the temperature sensor is as follows:

R_t＝R_t0+R_t0x A x t; wherein the content of the first and second substances,

R_tresistance value at different temperatures, R_t0The resistance value at 0 degree and the temperature coefficient A of 3.97X 10^-3DEG C, t is an input temperature coefficient variable;

the conversion operation formula of the temperature operational amplifier circuit is as follows:

U_t＝2.52×U_2t-3275; wherein the content of the first and second substances,

U_tthe constant current is the temperature equivalent voltage value of the temperature t at 1 mAmp;

U_2t＝U_1t+1200；

U_1t＝U_t0+U_t0×A×t；

U_t0＝R_t0×1。

4. the combined relative humidity sensor of claim 1, wherein the humidity sensor is a semiconductor ceramic humidity sensitive sensor.

5. The combined relative humidity sensor according to claim 4,

the input-output characteristic equation of the humidity sensor is as follows:

R_P＝R_P0+R_P0xBxP; wherein the content of the first and second substances,

R_Presistance values for output variables at different humidities; r_P0The humidity-sensitive resistance value is the humidity-sensitive resistance value when the partial pressure of water vapor in the atmosphere is zero; b is humidity sensitivity coefficient, and 2.78/mbar is taken; p is a partial pressure input variable (mbar) of water vapor in the atmosphere;

the conversion operation formula of the humidity operational amplifier circuit is as follows:

P＝3.6×10^-3×(U_2P) -4.7; wherein the content of the first and second substances,

p is the humidity equivalent voltage value with the constant current of 1 mAmp;

U_2P＝U_1P+1200；

U_1P＝U_P0+U_P0×B×P；

U_1P＝R_P×1。

6. the combined relative humidity sensor according to claim 1, wherein the relative humidity is calculated by the formula:

R_Hf＝(P)/(P_S)＝(U_po)/(U_ps) (ii) a Wherein the content of the first and second substances,

(P) is the actual partial pressure of water vapor to be measured in the atmosphere, and the unit is mbar; (U)_po) Is its voltage equivalent in mv; (P)_S) The unit is the saturated partial pressure of water vapor in the atmosphere at the same temperature and the unit is mbar; (U)_ps) Is its voltage equivalent in mv;

ln (R)_Hf)＝Ln(U_P0)-Ln(U_PS) (ii) a Wherein Ln (U)_PS)＝1.86+0.0625×U_t；

The calculation formula of the relative humidity in the relative humidity operation circuit is as follows:

Ln(R_Hf)＝Ln(U_p)-Ln(10)-Ln(U_ps)＝Ln(U_p)-4.16-0.0625×(Ut)＝(U₀the sum of (1); wherein the content of the first and second substances,

U_t＝2.52×U_2t-3275。

7. the combined relative humidity sensor of claim 1, further comprising:

and the constant current source module is used for providing a constant current source.

8. The combined rh sensor of claim 7, wherein the constant current source module is a LM317 type constant current source module.

Technical Field

The invention relates to the technical field of sensors, in particular to a combined type relative humidity sensor.

Background

The relative humidity is the ratio (0-1) of the partial pressure of water vapor (mbar) in the atmosphere and the partial pressure of saturated water vapor at the same temperature, is not a physical quantity per se, but contains information of two physical quantities, and the denominator value in the ratio is a nonlinear function of both the partial pressure of saturated water vapor and the ambient temperature, which causes technical difficulties in designing and manufacturing the relative humidity sensor. The state of the prior art is that two types of sensitive elements are adopted to respectively receive real water vapor partial pressure and humidity information, then the linear conversion of electric signals is realized through a corresponding hardware circuit platform and special development software, and finally the electric signals of relative humidity are obtained.

The prior art has the defects of complex hardware circuit, long period for developing special nonlinear processing software, high cost for forming a complete relative humidity automatic instrument and long period for constructing and maintaining a system.

Therefore, the present invention provides a combined type relative humidity sensor which overcomes the above problems, realizes the conversion precision to be adjustable, has a short period for forming an automatic instrument system, is high in convenience, and has a simple hardware structure.

Disclosure of Invention

Aiming at the technical problems, the invention aims to solve the problems that the relative humidity sensor in the prior art has complex hardware circuit and longer period for developing special nonlinear processing software, so that the cost for forming a complete relative humidity automatic instrument is higher, and the period for constructing and maintaining a system is longer, thereby providing the combined relative humidity sensor which overcomes the problems, realizes that the conversion precision can be regulated and controlled, has shorter period for forming the automatic instrument system, is high in convenience and has simple hardware structure.

In order to achieve the above object, the present invention provides a combined relative humidity sensor, comprising:

a temperature sensor that detects a temperature in an environment;

a humidity sensor for detecting humidity in the environment;

the temperature operational amplifier circuit is used for converting and operating the temperature value input by the temperature sensor to output a temperature equivalent voltage value;

the humidity operational amplifier circuit is used for converting and operating the humidity value input by the humidity sensor to output a humidity equivalent voltage value;

and the relative humidity computing circuit computes the relative humidity according to the temperature equivalent voltage value and the humidity equivalent voltage value by utilizing a logarithm computing component and an inverse logarithm computing component.

Preferably, the temperature sensor is a platinum thermistor pt 100.

Preferably, the basic equation of the input-output characteristic of the temperature sensor is:

R_t＝R_t0+R_t0x A x t; wherein the content of the first and second substances,

R_tresistance value at different temperatures, R_t0The resistance value at 0 degree and the temperature coefficient A of 3.97X 10^-3DEG C, t is an input temperature coefficient variable;

the conversion operation formula of the temperature operational amplifier circuit is as follows:

U_t＝2.52×U_2t-3275; wherein the content of the first and second substances,

U_tthe constant current is the temperature equivalent voltage value of the temperature t at 1 mAmp;

U_2t＝U_1t+1200；

U_1t＝U_t0+U_t0×A×t；

U_t0＝R_t0×1。

preferably, the humidity sensor is a semiconductor ceramic humidity sensor.

Preferably, the input-output characteristic equation of the humidity sensor is:

R_P＝R_P0+R_P0xBxP; wherein the content of the first and second substances,

R_Presistance values for output variables at different humidities; r_P0The humidity-sensitive resistance value is the humidity-sensitive resistance value when the partial pressure of water vapor in the atmosphere is zero; b is humidity sensitivity coefficient, and 2.78/mbar is taken; p is a partial pressure input variable (mbar) of water vapor in the atmosphere;

the conversion operation formula of the humidity operational amplifier circuit is as follows:

P＝3.6×10^-3×(U_2P) -4.7; wherein the content of the first and second substances,

p is the humidity equivalent voltage value with the constant current of 1 mAmp;

U_2P＝U_1P+1200；

U_1P＝U_P0+U_P0×B×P；

U_1P＝R_P×1。

preferably, the calculation formula of the relative humidity is:

R_Hf＝(P)/(P_S)＝(U_po)/(U_ps) (ii) a Wherein the content of the first and second substances,

(P) is the actual partial pressure of water vapor to be measured in the atmosphere, and the unit is mbar; (U)_po) Is its voltage equivalent in mv; (P)_S) The unit is the saturated partial pressure of water vapor in the atmosphere at the same temperature and the unit is mbar; (U)_ps) Is its voltage equivalent in mv;

ln (R)_Hf)＝Ln(U_P0)-Ln(U_PS) (ii) a Wherein Ln (U)_PS)＝1.86+0.0625×U_t

The calculation formula of the relative humidity in the relative humidity operation circuit is as follows:

Ln(R_Hf)＝Ln(U_p)-Ln(10)-Ln(U_ps)＝Ln(U_p)-4.16-0.0625×(Ut)＝(U₀sum of (1)

(ii) a Wherein the content of the first and second substances,

U_t＝2.52×U_2t-3275。

preferably, the combined relative humidity sensor further comprises:

and the constant current source module is used for providing a constant current source.

Preferably, the constant current source module is an LM317 type constant current source module.

According to the technical scheme, the combined relative humidity sensor provided by the invention has the beneficial effects in the process that: the conversion precision can be regulated and controlled when the automatic instrument system is used, the period for forming the automatic instrument system is short, the convenience for forming the automatic instrument is high, and the whole hardware structure of the sensor is simple and easy and the cost is low.

Additional features and advantages of the invention will be set forth in the detailed description which follows; and the parts not involved in the invention are the same as or can be realized by the prior art.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

FIG. 1 is a block diagram of a combined RH sensor in accordance with a preferred embodiment of the present invention;

FIG. 2 is a circuit schematic of a temperature operational amplifier circuit provided in a preferred embodiment of the present invention;

FIG. 3 is a circuit schematic of a humidity operational amplifier circuit provided in a preferred embodiment of the present invention;

FIG. 4 is a schematic circuit diagram of a relative humidity arithmetic circuit provided in a preferred embodiment of the present invention;

FIG. 5 is a schematic circuit diagram of a relative humidity arithmetic circuit provided in a preferred embodiment of the present invention;

fig. 6 is a schematic circuit diagram of a relative humidity operation circuit provided in a preferred embodiment of the present invention.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

In the present invention, unless otherwise specified, the directional words "upper, lower, inner, outer" and the like included in the terms merely represent the orientation of the terms in a conventional use state or are colloquially understood by those skilled in the art, and should not be construed as limiting the terms.

As shown in fig. 1-6, the present invention provides a combined relative humidity sensor comprising:

a temperature sensor that detects a temperature in an environment;

a humidity sensor for detecting humidity in the environment;

the temperature operational amplifier circuit is used for converting and operating the temperature value input by the temperature sensor to output a temperature equivalent voltage value;

the humidity operational amplifier circuit is used for converting and operating the humidity value input by the humidity sensor to output a humidity equivalent voltage value;

and the relative humidity computing circuit computes the relative humidity according to the temperature equivalent voltage value and the humidity equivalent voltage value by utilizing a logarithm computing component and an inverse logarithm computing component.

In a preferred embodiment of the present invention, the temperature sensor is a platinum thermistor pt 100.

In a preferred embodiment of the present invention, the basic equation of the input-output characteristic of the temperature sensor is:

R_t＝R_t0+R_t0x A x t; wherein the content of the first and second substances,

R_tresistance value at different temperatures, R_t0The resistance value at 0 degree and the temperature coefficient A of 3.97X 10^-3DEG C, t is an input temperature coefficient variable;

the conversion operation formula of the temperature operational amplifier circuit is as follows:

U_t＝2.52×U_2t-3275; wherein the content of the first and second substances,

U_tthe constant current is the temperature equivalent voltage value of the temperature t at 1 mAmp;

U_2t＝U_1t+1200；

U_1t＝U_t0+U_t0×A×t；

U_t0＝R_t0×1。

in a preferred embodiment of the invention, the humidity sensor is a semiconductor ceramic humidity sensor.

In a preferred embodiment of the present invention, the input-output characteristic equation of the humidity sensor is:

R_P＝R_P0+R_P0xBxP; wherein the content of the first and second substances,

R_Presistance values for output variables at different humidities; r_P0The humidity-sensitive resistance value is the humidity-sensitive resistance value when the partial pressure of water vapor in the atmosphere is zero; b is humidity sensitivity coefficient, 2.78 is takenA/mbar; p is a partial pressure input variable (mbar) of water vapor in the atmosphere;

the conversion operation formula of the humidity operational amplifier circuit is as follows:

P＝3.6×10^-3×(U_2P) -4.7; wherein the content of the first and second substances,

p is the humidity equivalent voltage value with the constant current of 1 mAmp;

U_2P＝U_1P+1200；

U_1P＝U_P0+U_P0×B×P；

U_1P＝R_P×1。

in a preferred embodiment of the invention, the calculation formula of the relative humidity is:

R_Hf＝(P)/(P_S)＝(U_po)/(U_ps) (ii) a Wherein the content of the first and second substances,

(P) is the actual partial pressure of water vapor to be measured in the atmosphere, and the unit is mbar; (U)_po) Is its voltage equivalent in mv; (P)_S) The unit is the saturated partial pressure of water vapor in the atmosphere at the same temperature and the unit is mbar; (U)_ps) Is its voltage equivalent in mv;

ln (R)_Hf)＝Ln(U_P0)-Ln(U_PS) (ii) a Wherein Ln (U)_PS)＝1.86+0.0625×U_t

The calculation formula of the relative humidity in the relative humidity operation circuit is as follows:

Ln(R_Hf)＝Ln(U_p)-Ln(10)-Ln(U_ps)＝Ln(U_p)-4.16-0.0625×(Ut)＝(U₀sum of (1)

(ii) a Wherein the content of the first and second substances,

U_t＝2.52×U_2t-3275。

in a preferred embodiment of the present invention, the combined relative humidity sensor further comprises:

and the constant current source module is used for providing a constant current source.

In a preferred embodiment of the present invention, the constant current source module is an LM317 type constant current source module.

According to the above, the working principle and the basic principle of the combined type relative humidity sensor provided by the invention are as follows:

firstly, a platinum thermal resistor pt100 is selected as a temperature sensor, and the basic equation of the input-output characteristic of the temperature sensor is as follows: r_t＝R_t0+R_t0Formula 1 of x A x t

In the formula R_tResistance value at different temperatures, R_t0The resistance value at 0 degree and the temperature coefficient A of 3.97X 10^-3DEG C, t is an input temperature coefficient variable;

equation 1 describes a linear relationship of the temperature value to the resistance value.

When a constant current of 1(ma) is turned on as in equation 1, equation 1 will become:

U_1t＝U_t0+U_t0x A x t formula 2

In the above formula, U_1tAt R corresponding to temperature t_tThe output voltage (mv) across the terminals,

U_t0100(mv), R at 0 ℃_t0Voltage across (mv);

now a new output variable U is introduced_2t(mv), and order U_2t＝U_1t+1200(mv),

Equation 2 can then be rewritten as:

U_2t＝U_1t+1200 ═ 1300+0.397 × (t) (mv) formula 3;

now, the positions of the variables and constants in the above formula are slightly exchanged to obtain:

t＝2.52×U_2t3275 equation 4;

the two terms on the right of equation 4 both have dimensions of mv voltage, which can be written as:

U_t＝2.52×U_2t-3275(mv) equation 5;

formula 5 is a voltage equivalent equation of temperature t, which is an ideal basis for designing an arithmetic circuit,

it comprises a multiplication operation and a subtraction operation; a circuit diagram for implementing such an algorithm is shown in fig. 2;

secondly, the humidity of the positive humidity sensitivity coefficient of the semiconductor ceramic is selectedThe sensitive sensor group is used as a humidity sensor, and the input-output characteristic equation is as follows: r_P＝R_P0+R_P0xBxP formula 6;

in the formula R_PResistance values for output variables at different humidities; r_P0The humidity-sensitive resistance value is the humidity-sensitive resistance value when the partial pressure of water vapor in the atmosphere is zero; b is humidity sensitivity coefficient, and 2.78/mbar is taken; p is a partial pressure input variable (mbar) of water vapor in the atmosphere;

r in equation 6_PWith a constant current of 1ma, equation 6 becomes:

U_1P＝U_P0+U_P0xBxP (mv) formula 7;

by operating similarly to the upper section temperature sensor

P＝3.6×10^-3×(U_2P) 4.7 equation 8;

the above formula is a voltage equivalent formula of humidity variable, wherein U_2P＝U_1P+1200(mv)；

The two terms on the right of equation 8 both have a voltage dimension, which can be denoted as U_P0Equivalent voltage (mv);

the operational amplifier circuit designed according to the formula 8 is shown in fig. 3, and it should be noted that 10 times of amplification gain is also arranged in the final operational amplifier to ensure the operational accuracy of the subsequent circuit.

Then, the design principle of the relative humidity arithmetic circuit is as follows:

the formula for calculating relative humidity is:

R_Hf＝(P)/(P_S)＝(U_po)/(U_ps) Equation 10

Wherein, (P) is the actual partial pressure of water vapor to be measured in the atmosphere, and the unit is mbar; (U)_po) Is its voltage equivalent in mv; (P)_S) The unit is the saturated partial pressure of water vapor in the atmosphere at the same temperature and the unit is mbar; (U)_ps) Is its voltage equivalent in mv;

ln (R)_Hf)＝Ln(U_P0)-Ln(U_PS) Equation 11;

in the formula, Ln (U)_PS)＝1.86+0.0625×U_tEquation 12;

two constant coefficients of 1.86 and 0.0625 are calculated by solving a linear fitting equation by using a least square method, and if (Upo) is enlarged by 10 times, the linear fitting equation is recorded as:

(U_p)＝10×(U_po) Equation 13;

now substituting equation 12 and equation 13 into equation 11, we get:

Ln(R_Hf)＝Ln(U_p)-Ln(10)-Ln(U_ps)＝Ln(U_p)-4.16-0.0625×(Ut)＝(U₀sum of (1)

Equation 14

In the above formula, U_t＝2.52×U_2t3275, and Ln (U) therein_p) The output voltage is taken from the Ln operational amplifier assembly;

obtaining Ln (U)_p) See fig. 4 and 5 for the operational circuit of (U's sum);

as shown in fig. 3, the transfer characteristics of the circuit are:

V₀＝434×Ln(U_p) Equation 15;

the auxiliary voltage is adjusted to E10 mv;

in pair Ln (R)_Hf) When restoring: after the sum of U is automatically calculated by the operational amplifier circuit module according to the formula 14, the sum is sent to the inverse logarithm or exponential operation module to recover (R)_Hf) The original value of (2); the anti-log operation circuit is shown in figure 6; the transfer characteristics are as follows:

V₀＝e^-0.0023×(V_i) Equation 16;

Ln(-1)(Ln(R_Hf) Ln (-1) (sum of U) ═ R_HfEquation 17;

here, Ln (-1) refers to the inverse logarithmic calculation of Ln.

In summary, the combined type relative humidity sensor provided by the invention overcomes the problems that the relative humidity sensor in the prior art has complicated hardware circuit and longer period for developing special nonlinear processing software, so that the cost for forming a complete relative humidity automatic instrument is higher, and the period for constructing and maintaining a system is also longer.

The preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications can be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.

It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and the invention is not described in any way for the possible combinations in order to avoid unnecessary repetition.

In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.