阅读说明：本技术 一种用于智能电气阀门定位器的显示屏系统及其应用方法 (Display screen system for intelligent electric valve positioner and application method thereof ) 是由 薛斌 黄萍 俞利明 胡孟杰 于 2020-11-30 设计创作，主要内容包括：本发明提供了一种用于智能电气阀门定位器的显示屏系统及其应用方法,所述系统包括：信号取样模块、CPU模块、电压调节模块、OLED显示屏；其中：信号取样模块,与CPU模块连接,用于接收外部输入的4mA～20mA信号,并将其转化为电压模拟信号输入CPU模块进行A/D转换；CPU模块,分别与电压调节模块和OLED显示屏连接,将信号取样模块发送的电压模拟信号转换为数字量N,并检测其大小；根据检测结果去改变OLED显示屏的工作电压,并对OLED显示屏的对比度进行配置；OLED显示屏分别与电压调节模块和CPU模块连接,CPU模块通过控制电压调节模块去改变OLED显示屏的工作电压。(The invention provides a display screen system for an intelligent electric valve positioner and an application method thereof, wherein the system comprises: the device comprises a signal sampling module, a CPU module, a voltage regulating module and an OLED display screen; wherein: the signal sampling module is connected with the CPU module and used for receiving an externally input 4 mA-20 mA signal, converting the signal into a voltage analog signal and inputting the voltage analog signal into the CPU module for A/D conversion; the CPU module is respectively connected with the voltage regulating module and the OLED display screen, converts the voltage analog signal sent by the signal sampling module into a digital quantity N and detects the magnitude of the digital quantity N; changing the working voltage of the OLED display screen according to the detection result, and configuring the contrast of the OLED display screen; the OLED display screen is respectively connected with the voltage regulation module and the CPU module, and the CPU module changes the working voltage of the OLED display screen by controlling the voltage regulation module.)

1. A display screen system for an intelligent electrical valve positioner, comprising: the device comprises a signal sampling module, a CPU module, a voltage regulating module and an OLED display screen; wherein:

the signal sampling module is connected with the CPU module and used for receiving an externally input 4 mA-20 mA signal, converting the signal into a voltage analog signal and inputting the voltage analog signal into the CPU module for A/D conversion;

the CPU module is respectively connected with the voltage regulating module and the OLED display screen, converts the voltage analog signal sent by the signal sampling module into a digital quantity N and detects the magnitude of the digital quantity N; changing the working voltage of the OLED display screen according to the detection result, and configuring the contrast of the OLED display screen;

the OLED display screen is respectively connected with the voltage regulation module and the CPU module, and the CPU module changes the working voltage of the OLED display screen by controlling the voltage regulation module.

2. The display screen system of claim 1, wherein the CPU module is pre-set with k thresholds: a first threshold, a second threshold, …, a kth threshold; k is an integer greater than 1;

the CPU module converts the k thresholds into corresponding digital quantity code values respectively to obtain: a first code value, a second code value, …, a kth code value;

after detection, if N is smaller than a first code value, the CPU module controls the voltage regulating module to output a first working voltage to the OLED display screen, and meanwhile, the OLED display screen is adjusted to have a first contrast;

if N is larger than or equal to the first code value and smaller than the second code value, the CPU module controls the voltage regulating module to output a second working voltage to the OLED display screen, and meanwhile, the OLED display screen is adjusted to have a second contrast;

……

if N is larger than or equal to the k-1 code value and smaller than the k code value, the CPU module controls the voltage regulating module to output the k working voltage to the OLED display screen, and meanwhile, the OLED display screen is adjusted to have the k contrast;

if the N is larger than or equal to the k code value, the CPU module controls the voltage regulating module to output the k +1 working voltage to the OLED display screen, and meanwhile, the OLED display screen is adjusted to have the k +1 contrast.

3. The display screen system of claim 2, wherein none of the first operating voltage, the second operating voltage, … …, and the k +1 operating voltage is greater than 3.3V; the first threshold value, the second threshold value, the … threshold value and the k-th threshold value are all in the range of 4 mA-20 mA.

4. The display screen system of claim 1, wherein the CPU is provided with a communication interface and a voltage control interface; the communication interface is connected with the OLED display screen; the voltage control interface is connected with the voltage regulating module;

the OLED display screen is provided with a GND pin and a VCC pin; and the voltage regulation module is respectively connected with a GND pin and a VCC pin of the OLED display screen.

5. The display screen system of claim 4, wherein the voltage control interface includes a first pin OLED _ ON1, a second pin OLED _ ON 2;

the voltage regulation module further comprises: the grounding part is connected with the power supply part;

the ground part includes: the resistor R21, the resistor R22, the resistor R53 and the MOS transistor Q9; the first end of the resistor R21 is connected with the first pin OLED _ ON1, and the second end of the resistor R21 is respectively connected with the first end of the resistor R22 and the gate of the MOS transistor Q9; the second end of the resistor R22 and the source electrode of the MOS transistor Q9 are both grounded; the drain electrode of the MOS tube Q9 is respectively connected with the first end of the resistor R53 and the GND pin of the OLED display screen; the second end of the resistor R53 is grounded;

the power connection part comprises:

the resistor R54, the resistor R55, the resistor R66, the MOS transistor Q10 and the capacitor C26; the first end of the resistor R54 and the gate of the MOS transistor Q10 are both connected with the second pin OLED _ ON 2; the second end of the resistor R54, the source electrode of the MOS transistor Q10, the first end of the resistor R55, the first end of the resistor R66 and the first end of the capacitor C26 are all connected with 3V voltage; the drain of the MOS transistor Q10, the second end of the resistor R55 and the second end of the resistor R66 are all connected with a VCC pin of the OLED display screen.

6. The display screen system of claim 5, wherein the CPU module changes the operating voltage output by the voltage regulating module to the OLED display screen by performing switching control on a MOS transistor Q9 and a MOS transistor Q10.

7. A method of using a display screen system for an intelligent electrical valve positioner, based on the display screen system of any one of claims 1 to 6, comprising the steps of:

s1: externally inputting a 4 mA-20 mA signal to a signal sampling module, converting the signal into a voltage analog signal by the signal sampling module, and inputting the voltage analog signal into a CPU module;

s2: the CPU module converts the voltage analog signal sent by the signal sampling module into a digital quantity N and detects the magnitude of the digital quantity N; and changing the working voltage of the OLED display screen according to the detection result, and configuring the contrast of the OLED display screen.

8. The method of application according to claim 7, wherein said step S2 further comprises:

s21: the CPU module converts the voltage analog signal sent by the signal sampling module into a digital quantity N;

s22: the CPU module is preset with k thresholds: a first threshold, a second threshold, …, a kth threshold; k is an integer greater than 1; the CPU module converts the k thresholds into corresponding digital quantity code values respectively to obtain: a first code value, a second code value, …, a kth code value;

after detection, if N is smaller than a first code value, the CPU module controls the voltage regulating module to output a first working voltage to the OLED display screen, and meanwhile, the OLED display screen is adjusted to have a first contrast;

if N is larger than or equal to the first code value and smaller than the second code value, the CPU module controls the voltage regulating module to output a second working voltage to the OLED display screen, and meanwhile, the OLED display screen is adjusted to have a second contrast;

……

if N is larger than or equal to the k-1 code value and smaller than the k code value, the CPU module controls the voltage regulating module to output the k working voltage to the OLED display screen, and meanwhile, the OLED display screen is adjusted to have the k contrast;

if the N is larger than or equal to the k code value, the CPU module controls the voltage regulating module to output the k +1 working voltage to the OLED display screen, and meanwhile, the OLED display screen is adjusted to have the k +1 contrast.

Technical Field

The invention relates to the field of displays, in particular to a display screen system for an intelligent electric valve positioner and an application method thereof.

Background

The intelligent electro-pneumatic valve positioner at present adopts liquid crystal display to realize man-machine interactive function because the low-power consumption demand basically, and liquid crystal display has that the visual angle is little and work will show unclear or the shortcoming that does not have the demonstration at the ultra-low temperature. If the OLED display screen is adopted, the power consumption is large, and the normal work of the intelligent electric valve positioner can be influenced.

1) The liquid crystal display works at ultralow temperature, and the display effect is poor:

the working environment of the intelligent electropneumatic valve positioner is-40-80 ℃, and the liquid crystal screen generally has unclear or non-displayable display at the temperature of-20 ℃ and below.

2) The visual angle of the liquid crystal screen is small, and the visual effect under strong light is not good:

the liquid crystal display screen has a small visual angle, and the display content is unclear when the liquid crystal display screen stands on the side surface of the intelligent electric valve positioner or looks at the screen under strong light.

3) The OLED display screen has large power consumption, and the normal work of the valve positioner is influenced.

The two-wire system intelligent electric valve positioner inputs 4 mA-20 mA signals, the OLED display screen has large power consumption, and the OLED display screen cannot be normally started when the 4mA signals are input.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a display screen system for an intelligent electric valve positioner and an application method thereof, so as to solve the problem that the existing man-machine interaction display device of the intelligent electric valve positioner has poor display effect in the environments of low temperature, high brightness, large visual angle, low power consumption and the like. The technical scheme of the invention is as follows:

a display screen system for an intelligent electrical valve positioner, comprising: the device comprises a signal sampling module, a CPU module, a voltage regulating module and an OLED display screen; wherein:

the signal sampling module is connected with the CPU module and used for receiving an externally input 4 mA-20 mA signal, converting the signal into a voltage analog signal and inputting the voltage analog signal into the CPU module;

the CPU module is respectively connected with the voltage regulating module and the OLED display screen, converts the voltage analog signal sent by the signal sampling module into a digital quantity N and detects the magnitude of the digital quantity N; changing the working voltage of the OLED display screen according to the detection result, and configuring the contrast of the OLED display screen;

the OLED display screen is respectively connected with the voltage regulation module and the CPU module, and the CPU module changes the working voltage of the OLED display screen by controlling the voltage regulation module.

Optionally, the CPU module is preset with k thresholds: a first threshold, a second threshold, …, a kth threshold; k is an integer greater than 1; the CPU module converts the k thresholds into corresponding digital quantity code values respectively to obtain: a first code value, a second code value, …, a kth code value;

after detection, if N is smaller than a first code value, the CPU module controls the voltage regulating module to output a first working voltage to the OLED display screen, and meanwhile, the OLED display screen is adjusted to have a first contrast;

if N is larger than or equal to the first code value and smaller than the second code value, the CPU module controls the voltage regulating module to output a second working voltage to the OLED display screen, and meanwhile, the OLED display screen is adjusted to have a second contrast;

……

if N is larger than or equal to the k-1 code value and smaller than the k code value, the CPU module controls the voltage regulating module to output the k working voltage to the OLED display screen, and meanwhile, the OLED display screen is adjusted to have the k contrast;

if the N is larger than or equal to the k code value, the CPU module controls the voltage regulating module to output the k +1 working voltage to the OLED display screen, and meanwhile, the OLED display screen is adjusted to have the k +1 contrast.

Optionally, the first operating voltage, the second operating voltage, … … and the (k + 1) th operating voltage are not higher than the first threshold, the second threshold, … and the kth threshold of 3.3V, and are all in the range of 4mA to 20 mA.

Optionally, the CPU is provided with a communication interface and a voltage control interface; the communication interface is connected with the OLED display screen; the voltage control interface is connected with the voltage regulating module;

the OLED display screen is provided with a GND pin and a VCC pin; and the voltage regulation module is respectively connected with a GND pin and a VCC pin of the OLED display screen.

Optionally, the voltage control interface comprises a first pin OLED _ ON1, a second pin OLED _ ON 2;

the voltage regulation module further comprises: the grounding part is connected with the power supply part;

the ground part includes: the resistor R21, the resistor R22, the resistor R53 and the MOS transistor Q9; the first end of the resistor R21 is connected with the first pin OLED _ ON1, and the second end of the resistor R21 is respectively connected with the first end of the resistor R22 and the gate of the MOS transistor Q9; the second end of the resistor R22 and the source electrode of the MOS transistor Q9 are both grounded; the drain electrode of the MOS tube Q9 is respectively connected with the first end of the resistor R53 and the GND pin of the OLED display screen; the second end of the resistor R53 is grounded;

the power connection part comprises:

the resistor R54, the resistor R55, the resistor R66, the MOS transistor Q10 and the capacitor C26; the first end of the resistor R54 and the gate of the MOS transistor Q10 are both connected with the second pin OLED _ ON 2; the second end of the resistor R54, the source electrode of the MOS transistor Q10, the first end of the resistor R55, the first end of the resistor R66 and the first end of the capacitor C26 are all connected with 3V voltage; the drain of the MOS transistor Q10, the second end of the resistor R55 and the second end of the resistor R66 are all connected with a VCC pin of the OLED display screen.

Optionally, the CPU module changes the operating voltage output by the voltage regulating module to the OLED display screen by performing switching control on the MOS transistor Q9 and the MOS transistor Q10.

An application method of a display screen system for an intelligent electric valve positioner is based on the display screen system, and comprises the following steps:

s1: externally inputting a 4 mA-20 mA signal to a signal sampling module, converting the signal into a voltage analog signal by the signal sampling module, and inputting the voltage analog signal into a CPU module;

s2: the CPU module converts the voltage analog signal sent by the signal sampling module into a digital quantity N and detects the magnitude of the digital quantity N; and changing the working voltage of the OLED display screen according to the detection result, and configuring the contrast of the OLED display screen.

Optionally, the step S2 further includes:

s21: the CPU module converts the voltage analog signal sent by the signal sampling module into a digital quantity N;

s22: the CPU module is preset with k thresholds: a first threshold, a second threshold, …, a kth threshold; k is an integer greater than 1; the CPU module converts the k thresholds into corresponding digital quantity code values respectively to obtain: a first code value, a second code value, …, a kth code value;

after detection, if N is smaller than a first code value, the CPU module controls the voltage regulating module to output a first working voltage to the OLED display screen, and meanwhile, the OLED display screen is adjusted to have a first contrast;

if N is larger than or equal to the first code value and smaller than the second code value, the CPU module controls the voltage regulating module to output a second working voltage to the OLED display screen, and meanwhile, the OLED display screen is adjusted to have a second contrast;

……

if N is larger than or equal to the k-1 code value and smaller than the k code value, the CPU module controls the voltage regulating module to output the k working voltage to the OLED display screen, and meanwhile, the OLED display screen is adjusted to have the k contrast;

if the N is larger than or equal to the k code value, the CPU module controls the voltage regulating module to output the k +1 working voltage to the OLED display screen, and meanwhile, the OLED display screen is adjusted to have the k +1 contrast.

Compared with the prior art, the invention has the following beneficial effects:

(1) the display screen is resistant to low temperature. The invention realizes the man-machine interaction function by replacing the liquid crystal display screen adopted by the existing intelligent electric valve positioner with the OLED display screen, so that the display screen can normally work at the temperature of-40 ℃.

(2) The display screen has wide visual angle and high resolution. The invention realizes the man-machine interaction function by replacing the liquid crystal display screen adopted by the existing intelligent electric valve positioner with the OLED display screen, so that the display screen achieves full visual angle and high resolution.

(3) And the OLED display screen is applied to low power consumption. The invention solves the problem that the normal work of the intelligent electric valve positioner is influenced due to the large power consumption of the OLED display screen, and the normal work of the OLED display screen in a low-power consumption environment is realized by an application method of controlling the OLED display screen to display different brightness in sections through the combination of software and hardware design.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

FIG. 1 is a functional block diagram of a display screen system for an intelligent electrical valve positioner according to an embodiment of the present invention;

FIG. 2 is a hardware circuit diagram of a display screen system for an intelligent electrical valve positioner according to an embodiment of the present invention;

FIG. 3 is a flow chart of a method of using a display screen system for an intelligent electrical valve positioner according to an embodiment of the present invention.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.

As shown in fig. 1 and 2, the present embodiment discloses a display screen system for an intelligent electrical valve positioner, comprising: the system comprises a signal sampling module 10, a CPU module 20, a voltage regulating module 30 and an OLED display screen 40; wherein:

the signal sampling module 10 is connected with the CPU module 20 and used for receiving an externally input 4 mA-20 mA signal, converting the signal into a voltage analog signal and inputting the voltage analog signal into the CPU module 20;

the CPU module 20 is respectively connected with the voltage regulating module 30 and the OLED display screen 40, converts the voltage analog signal sent by the signal sampling module 10 into a digital quantity N, and detects the magnitude of the digital quantity N; changing the working voltage of the OLED display screen 40 according to the detection result, and configuring the contrast of the OLED display screen 40; the contrast here is the brightness of the display screen.

The OLED display screen 40 is connected to the voltage adjusting module 30 and the CPU module 20, respectively, and the CPU module 20 controls the voltage adjusting module 30 to change the operating voltage of the OLED display screen 40.

In this embodiment, the OLED display screen 40 is used as a display terminal of the intelligent electrical valve positioner, the normal operating voltage range of the OLED display screen 40 is 1.7V-3.3V, the OLED display screen can operate at-40 ℃ to 85 ℃, and the OLED display screen has high definition and a large viewing angle, and these characteristics well solve the problem that the existing man-machine interactive display device of the intelligent electrical valve positioner has a poor display effect in environments such as low temperature, high brightness, and a large viewing angle, but the OLED display screen has high power consumption, and the normal brightness cannot be normally started when 4mA is input. And aiming at the problem of large power consumption, segmented brightness display design is carried out. After an external 4 mA-20 mA signal is input, the signal is converted into a voltage analog signal through the signal sampling module and is input into the CPU module, the CPU module detects the magnitude of the input signal after carrying out A/D conversion, and then controls different working voltages to output and change the brightness of the display screen according to the magnitude of the input signal.

The CPU module is preset with k thresholds: a first threshold, a second threshold, …, a kth threshold; k is an integer greater than 1; the CPU module converts the k thresholds into corresponding digital quantity code values respectively to obtain: a first code value, a second code value, …, a kth code value; the operation of converting the digital value by the threshold is a common operation in the CPU, and is not described in detail herein.

After detection, if N is smaller than a first code value, the CPU module controls the voltage regulating module to output a first working voltage to the OLED display screen, and meanwhile, the OLED display screen is adjusted to have a first contrast;

if N is larger than or equal to the first code value and smaller than the second code value, the CPU module controls the voltage regulating module to output a second working voltage to the OLED display screen, and meanwhile, the OLED display screen is adjusted to have a second contrast;

……

if N is larger than or equal to the k-1 code value and smaller than the k code value, the CPU module controls the voltage regulating module to output the k working voltage to the OLED display screen, and meanwhile, the OLED display screen is adjusted to have the k contrast;

if the N is larger than or equal to the k code value, the CPU module controls the voltage regulating module to output the k +1 working voltage to the OLED display screen, and meanwhile, the OLED display screen is adjusted to have the k +1 contrast.

Wherein, the first working voltage, the second working voltage, … … and the (k + 1) th working voltage are not higher than 3.3V.

The first threshold value, the second threshold value, …, and the kth threshold value are all in the range of 4mA to 20mA (the range includes values of both endpoints).

The present embodiment is described by taking two thresholds as examples, as follows:

the CPU module is preset with two thresholds: a first threshold value and a second threshold value; wherein the first threshold value is 6mA, and the second threshold value is 8 mA. The specific values of the two thresholds are only examples, and the invention is not limited to the specific values. The CPU module converts the 2 thresholds into corresponding digital quantity code values respectively to obtain: a first code value and a second code value.

After detection, if N is smaller than a first code value, the CPU module limits the voltage and the current of the working voltage of the OLED display screen through the voltage adjusting module, and simultaneously reduces the contrast of the OLED display screen to enable the contrast to be a first contrast;

if N is larger than or equal to the first code value and smaller than the second code value, the CPU module controls the voltage adjusting module to output the normal working voltage of the OLED display screen, and simultaneously, the contrast of the OLED display screen is reduced to be a second contrast;

if the N is larger than or equal to the second code value, the CPU module controls the voltage adjusting module to output the normal working voltage of the OLED display screen, and simultaneously, the contrast of the OLED display screen is increased to be a third contrast.

The CPU module 20 is provided with a communication interface and a voltage control interface; the communication interface is connected with the OLED display screen 40; the voltage control interface is connected to the voltage regulation module 30. The CPU module 20 changes the contrast of the OLED display screen 40 through a communication interface; the CPU module 20 changes the operating voltage of the OLED display screen 40 through the voltage control interface.

The communication interface comprises five pins: OLED _ CLK, OLED _ DATA, OLED _ RES, OLED _ DC, OLED _ CS; the OLED display screen is provided with 7 pins: GND, VCC, SCL, SDA, RES, DC, CS; the voltage regulation module is connected with a GND pin and a VCC pin of the OLED display screen respectively. The other 5 pins SCL, SDA, RES, DC, CS are connected to the five pins OLED _ CLK, OLED _ DATA, OLED _ RES, OLED _ DC, OLED _ CS of the communication interface, respectively.

The voltage regulation module 30 further includes: the grounding part is connected with the power supply part;

the ground part includes: the resistor R21, the resistor R22, the resistor R53 and the MOS transistor Q9; the first end of the resistor R21 is connected with the first interface OLED _ ON1, and the second end of the resistor R21 is respectively connected with the first end of the resistor R22 and the gate of the MOS transistor Q9; the second end of the resistor R22 and the source electrode of the MOS transistor Q9 are both grounded; the drain electrode of the MOS tube Q9 is respectively connected with the first end of the resistor R53 and the GND pin of the OLED display screen; the second end of the resistor R53 is grounded; q9 is an N-channel enhancement type MOS tube; q10 is a P-channel enhancement MOS transistor.

The power connection part comprises:

the resistor R54, the resistor R55, the resistor R66, the MOS transistor Q10 and the capacitor C26; the first end of the resistor R54 and the gate of the MOS transistor Q10 are both connected with the second interface OLED _ ON 2; the second end of the resistor R54, the source electrode of the MOS transistor Q10, the first end of the resistor R55, the first end of the resistor R66 and the first end of the capacitor C26 are all connected with 3V voltage; the drain of the MOS transistor Q10, the second end of the resistor R55 and the second end of the resistor R66 are all connected with a VCC pin of the OLED display screen.

The CPU module changes the working voltage output to the OLED display screen by the voltage regulation module through switching control over the MOS tube Q9 and the MOS tube Q10.

If Q9 and Q10 are turned off at the same time, the 3V voltage is limited in voltage and limited in current through R53, R55 and R56; if Q9 is turned on and Q10 is turned off, the 3V voltage is limited in voltage and current through R55 and R56; if Q9 is turned off and Q10 is turned on, the 3V voltage is limited in voltage and current through R53; when Q9 and Q10 are turned on simultaneously, R53, R55 and R56 are all short-circuited, 3V voltage is output to the OLED display screen, and the voltage between the OLED display screen VCC and GND is about 3V at the moment.

Referring to fig. 3, the embodiment also discloses an application method of a display screen system for an intelligent electrical valve positioner, based on the display screen system, including the following steps:

s1: the external input 4 mA-20 mA signal to the signal sampling module 10, the signal sampling module 10 converts it into voltage analog signal and inputs it to the CPU module 20;

s2: the CPU module 20 converts the voltage analog signal sent by the signal sampling module into a digital value N and detects the magnitude thereof; and changing the working voltage of the OLED display screen 40 according to the detection result, and configuring the contrast of the OLED display screen 40.

Wherein the step S2 further includes:

s21: the CPU module converts the voltage analog signal sent by the signal sampling module into a digital signal N;

s22: the CPU module is preset with k thresholds: a first threshold, a second threshold, …, a kth threshold; k is an integer greater than 1; the CPU module converts the k thresholds into corresponding digital quantity code values respectively to obtain: a first code value, a second code value, …, a kth code value;

after detection, if N is smaller than a first code value, the CPU module controls the voltage regulating module to output a first working voltage to the OLED display screen, and meanwhile, the OLED display screen is adjusted to have a first contrast;

if N is larger than or equal to the first code value and smaller than the second code value, the CPU module controls the voltage regulating module to output a second working voltage to the OLED display screen, and meanwhile, the OLED display screen is adjusted to have a second contrast;

……

if N is larger than or equal to the k-1 code value and smaller than the k code value, the CPU module controls the voltage regulating module to output the k working voltage to the OLED display screen, and meanwhile, the OLED display screen is adjusted to have the k contrast;

if the N is larger than or equal to the k code value, the CPU module controls the voltage regulating module to output the k +1 working voltage to the OLED display screen, and meanwhile, the OLED display screen is adjusted to have the k +1 contrast.

In this embodiment, two thresholds are taken as an example for explanation, and the following are specifically described:

step S2 further includes: s21: the CPU module 20 converts the voltage analog signal transmitted from the signal sampling module 10 into a digital quantity N.

S22: the CPU module 20 is preset with two thresholds: a first threshold value and a second threshold value; wherein the first threshold value is 6mA, and the second threshold value is 8 mA. The specific values of the two thresholds are only examples, and the two thresholds are only within the range of 4mA to 20mA, and the invention does not limit the specific values. The CPU module 20 performs size detection on N according to the two thresholds.

The CPU module converts the 2 thresholds into corresponding digital quantity code values respectively to obtain: a first code value and a second code value.

If N is smaller than the first code value, the CPU module 20 limits the voltage and the current of the working voltage of the OLED display screen through the voltage adjusting module 30 (outputs the first working voltage), and simultaneously configures the OLED display screen through the communication interface to lower the contrast ratio to enable the contrast ratio to be the first contrast ratio, at the moment, the display screen has the minimum brightness (brightness control display), the power consumption is reduced, and the whole machine can be normally started when 3mA is input; i.e. a low operating voltage is maintained and a low display contrast is output.

If N is larger than or equal to the first code value and smaller than the second code value, the CPU module controls the voltage regulation module to output normal working voltage of the OLED display screen (output second working voltage), meanwhile, the CPU module configures the OLED display screen through the communication interface to lower the contrast so that the contrast is the second contrast, at the moment, the brightness of the display screen is relatively improved (brightness control display), the power consumption is increased, but the normal work of the whole machine is not influenced because the input signal is also increased; namely, the normal operating voltage is maintained, and the low display contrast is output.

If N is larger than or equal to the second code value, the CPU module controls the voltage regulation module to output normal working voltage of the OLED display screen (output third working voltage), meanwhile, the CPU module configures the OLED display screen through the communication interface to increase the contrast to be third contrast, and at the moment, the brightness of the display screen is relatively improved (brightness control display); namely, the normal working voltage is kept, and high display contrast is output.

In step S22, the step of "the CPU module performing voltage limiting and current limiting on the operating voltage of the OLED display screen through the voltage adjusting module" further includes:

the CPU module carries out switching control on MOS transistors Q9 and Q10, the low level is set to enable Q9 to be closed, the high level is set to enable Q10 to be closed, and voltage limiting and current limiting are carried out on 3V voltage through R53, R55 and R66. At the moment, the voltage between the OLED display screen VCC and the GND is smaller than the 3V working voltage, meanwhile, the CPU module configures the display screen through the communication interface to reduce the contrast, the display screen has minimum brightness (the brightness does not influence human-computer interaction), the power consumption is reduced, the whole machine can be normally started when 3mA (minimum starting current) is input, and the working requirement of the intelligent electric valve positioner is met.

In step S22, the step of controlling the voltage regulation module to output the normal operating voltage of the OLED display by the CPU module further includes:

the CPU module carries out switch control on MOS tubes Q9 and Q10, sets high level to enable Q9 to be started, sets low level to enable Q10 to be started, is equivalent to short circuit of R53, R55 and R66, voltage between the OLED screen VCC and GND is about 3V at the moment, and meanwhile, the CPU module configures the display screen through a communication interface to increase contrast and adjust high brightness of the display screen.

In this embodiment, a case of dividing the display into three segments of brightness (contrast) and 2 signal thresholds is taken as an example for explanation, and in the specific implementation, the input signal threshold for the display of several segments of brightness and each segment of display can be set according to the requirement.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.