CN116298491B - Pulse type direct current measurement method applied to backlight current detection of display screen - Google Patents
Pulse type direct current measurement method applied to backlight current detection of display screen Download PDFInfo
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- CN116298491B CN116298491B CN202310528383.9A CN202310528383A CN116298491B CN 116298491 B CN116298491 B CN 116298491B CN 202310528383 A CN202310528383 A CN 202310528383A CN 116298491 B CN116298491 B CN 116298491B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
- G01R19/16528—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values using digital techniques or performing arithmetic operations
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/25—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using digital measurement techniques
- G01R19/2506—Arrangements for conditioning or analysing measured signals, e.g. for indicating peak values ; Details concerning sampling, digitizing or waveform capturing
- G01R19/2509—Details concerning sampling, digitizing or waveform capturing
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
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Abstract
The application provides a pulse type direct current measurement method applied to backlight current detection of a display screen, which is applied to an MCU controller and comprises the following steps: the method comprises the steps of obtaining an original ADC measured value, wherein an MCU controller controls a current output unit to output square wave pulse current, a sampling unit samples the square wave pulse current and converts the square wave pulse current into a voltage signal, an ADC conversion unit carries out analog-to-digital conversion on the voltage signal to obtain the original ADC measured value, and the original ADC measured value is transmitted to the MCU controller by the ADC conversion unit; threshold separation is carried out on the original ADC measured value, and first data are obtained; sequencing the first data to obtain second data; determining a group of undetermined data from the second data, and performing average value calculation to obtain a voltage average value; based on the voltage average value and ohm law, a real current value is calculated and a current detection result is generated.
Description
Technical Field
The application relates to the field of display screen current detection, in particular to a pulse type direct current measurement method applied to display screen backlight current detection.
Background
Under current display backlight control techniques, many display backlights are driven by pulsed current, such as a 90 frame refresh rate, where the backlight current is not a constant current, but a 90Hz square wave pulsed current. The pulse current cannot be directly measured by the traditional method, and is usually converted into uniform direct current measurement by a hardware RC filtering mode. However, if the method is suitable for detecting currents with different frequencies, such as random frequency change (60 Hz, 75Hz, 90Hz, 120Hz, etc.) or too low frequency, the effect of RC filtering is seriously affected, so that the jitter is too large, the response to the current is obviously retarded, the measurement result is not accurate enough, and the difference from the true value is large.
Disclosure of Invention
The embodiment of the application aims to provide a pulse type direct current measurement method applied to backlight current detection of a display screen, so that pulse current can be directly measured, stable measurement can be realized without changing hardware when the control pulse frequency changes, quick response can be realized when the current changes, and a current value close to reality can be measured.
In order to achieve the above object, embodiments of the present application are realized by:
in a first aspect, an embodiment of the present application provides a pulsed dc current measurement method applied to backlight current detection of a display screen, where a pulsed dc current sampling measurement device includes a main point screen system with a built-in MCU controller and a power panel electrically connected to the MCU controller through a flat cable, where the power panel is integrated with a current output unit, a sampling unit and an ADC conversion unit, and where the method is applied to the MCU controller, and includes: the method comprises the steps that an original ADC measured value is obtained, wherein the MCU controller controls the current output unit to output square wave pulse current, the sampling unit samples the square wave pulse current and converts the square wave pulse current into a voltage signal, the ADC conversion unit carries out analog-to-digital conversion on the voltage signal to obtain the original ADC measured value, and the original ADC measured value is transmitted to the MCU controller by the ADC conversion unit; threshold separation is carried out on the original ADC measured value to obtain first data; sequencing the first data to obtain second data; determining a group of undetermined data from the second data, and performing average value calculation to obtain a voltage average value; and calculating a real current value and generating a current detection result based on the voltage average value and ohm law.
With reference to the first aspect, in a first possible implementation manner of the first aspect, performing threshold separation on the raw ADC measurement value to obtain first data, including: removing the values lower than a set threshold value from the original ADC measured value to obtain a residual value; and combining the residual values to obtain the first data.
With reference to the first aspect, in a second possible implementation manner of the first aspect, the ordering the first data to obtain second data includes: and carrying out ascending sort on all values in the first data to obtain the second data.
With reference to the first aspect, in a third possible implementation manner of the first aspect, from the first aspectDetermining a group of undetermined data in the two data, and carrying out average value calculation to obtain a voltage average value, wherein the method comprises the following steps: determining from the second data that the data is centeredxA numerical value as the pending data, wherein,xthe number of (2) does not exceed the total number of values in the second dataThe method comprises the steps of carrying out a first treatment on the surface of the And calculating the average value of the undetermined data to obtain the voltage average value.
With reference to the third possible implementation manner of the first aspect, in a fourth possible implementation manner of the first aspect, calculating a true current value and generating a current detection result based on the voltage average value and ohm's law includes: using the voltage average value, calculating a real current value using the following formula:，
wherein, the liquid crystal display device comprises a liquid crystal display device,for the real current value, < >>For the voltage mean>Is a resistor with a known resistance value; based on the true current value, a current detection result including the true current value is generated.
With reference to the fourth possible implementation manner of the first aspect, in a fifth possible implementation manner of the first aspect, generating a current detection result including the true current value based on the true current value includes: dividing the undetermined data into a high value group and a low value group based on the voltage average, wherein each numerical value in the high value group is higher than the voltage average, and each numerical value in the low value group is lower than the voltage average; calculating the average value of the high value group, subtracting the voltage average value from the average value of the high value group to obtain a voltage floating value, and calculating the average value of the low value group, subtracting the voltage average value from the voltage floating valueThe average value of the low value group obtains a voltage sinking value; dividing the voltage floating value by resistanceTo obtain a current float value, and dividing the voltage sink value by the resistance +.>Obtaining a current sinking value; generating a current detection result comprising the real current value, the current float value and the current sink value.
With reference to the fifth possible implementation manner of the first aspect, in a sixth possible implementation manner of the first aspect, after determining a current detection result, the method further includes: judging whether the real current value in the current detection result exceeds a safety threshold value or not; if the real current value exceeds a safety threshold, closing current output to protect a later stage; and if the real current value does not exceed the safety threshold value, regulating the square wave pulse current output by the current output unit based on the current detection result.
With reference to the sixth possible implementation manner of the first aspect, in a seventh possible implementation manner of the first aspect, adjusting the square wave pulse current output by the current output unit based on the current detection result includes: acquiring current parameters of a display screen to be tested; if the true current value is higher than the current parameter, calculating a first compensation current value based on the following formula:，
wherein, the liquid crystal display device comprises a liquid crystal display device,for the first compensation current value,/>For the current sinking value, ">For current parameter, +.>Is the real current value;
subtracting the first compensation current value on the basis of the square wave pulse current to obtain an adjusted square wave pulse current and outputting the adjusted square wave pulse current; if the true current value is lower than the current parameter, calculating a second compensation current value based on the following formula:，
wherein, the liquid crystal display device comprises a liquid crystal display device,for the second compensation current value,/>Is the current floating value->For current parameter, +.>Is the real current value; and adding the second compensation current value on the basis of the square wave pulse current to obtain and output the adjusted square wave pulse current.
The beneficial effects are that:
1. the MCU controller which utilizes pulse direct current sampling measurement controls the current output unit to output square wave pulse current, the sampling unit samples the square wave pulse current and converts the square wave pulse current into a voltage signal, the ADC conversion unit carries out analog-to-digital conversion on the voltage signal to obtain an original ADC measured value, the original ADC measured value is transmitted back to the MCU controller, and the MCU controller carries out measurement based on the original ADC measured value. Therefore, the pulse current can be directly measured, and the pulse current can be stably measured without changing hardware when the pulse frequency is controlled to change, so that the pulse current measuring device can be suitable for current detection scenes with different frequencies, and can quickly respond when the current is changed. Threshold separation is carried out on the original ADC measured value, and first data are obtained; sequencing the first data to obtain second data; determining a group of undetermined data from the second data, and performing average value calculation to obtain a voltage average value; based on the voltage average value and ohm law, a real current value is calculated and a current detection result is generated. In this way, current measurement with different frequencies can be dealt with, and data in the center of the current after sorting is separated, sorted and selected by using a threshold value as pending data (the group of pending data can well reflect a real current value), the measured current value is closer to the real current value, and detection is more accurate. And the MCU controller can also realize overcurrent protection based on a current detection result, regulate and control the output square wave pulse current, and is beneficial to improving the detection reliability.
2. Based on the voltage average value, the undetermined data are divided into a high value group and a low value group, a voltage floating value and a voltage sinking value are calculated, a current floating value and a current sinking value can be further calculated, and a current detection result containing a real current value, a current floating value and a current sinking value is generated. Judging whether the real current value exceeds a safety threshold value or not; closing the current output to protect the later stage when the safety threshold is exceeded; and if the safety threshold value is not exceeded, the output pulse square wave current is further regulated. The method for regulating and controlling not only considers the measured real current value, but also considers the influence of the current sinking value and the influence of the current floating value according to the conditions, calculates the corresponding compensation value to carry out compensation regulation and control, so that the regulated and controlled square wave pulse current can quickly and accurately reach the current parameter of the display screen to be tested, the reliability of subsequent detection is improved, and the control of the product quality is improved.
In order to make the above objects, features and advantages of the present application more comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments of the present application will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic diagram of a pulse dc sampling measurement device according to an embodiment of the present application.
Fig. 2 is a system block diagram of a pulse dc sampling measurement device according to an embodiment of the present application.
Fig. 3 is a circuit diagram of a current output unit employing the cross current output converter MP 3314.
Fig. 4 is a circuit diagram of a sampling unit employing LMP 8645.
Fig. 5 is a circuit diagram of an ADC conversion unit employing ADS 7828.
Fig. 6 is a flowchart of a pulsed dc current measurement method applied to backlight current detection of a display screen.
Fig. 7 is a schematic diagram of one raw ADC measurement.
Fig. 8 is a schematic diagram of numerical culling of raw ADC measurements.
Fig. 9 is a schematic diagram of the remaining values after threshold separation.
Fig. 10 is a schematic diagram of first data.
Fig. 11 is a schematic diagram of the second data.
Icon: 10-pulse type direct current sampling and measuring device; 11-a main dot screen system; 12-arranging wires; 13-a power panel; 131-a current output unit; 132-a sampling unit; a 133-ADC conversion unit; 20-an upper computer; 30-a display screen to be tested.
Detailed Description
The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application.
Referring to fig. 1 and 2, fig. 1 is a schematic diagram of a pulse dc sampling measurement device 10 according to an embodiment of the present application; fig. 2 is a system block diagram of a pulse dc sampling measurement device 10 according to an embodiment of the present application.
In this embodiment, the pulsed dc current sampling measurement device 10 includes a main screen system 11, a flat cable 12 and a power panel 13, where the main screen system 11 and the power panel 13 are electrically connected through the flat cable 12 (the flat cable 12 includes a first end and a second end opposite to each other, the first end is electrically connected to the MCU controller, and the second end is electrically connected to the power panel 13).
Illustratively, the main point screen system 11 is built with an MCU controller, and the MCU controller is electrically connected to an external host computer 20, so as to implement communication between the main point screen system 11 and the host computer 20. The main spot screen system 11 further includes necessary components such as a housing, an indicator light, an interface, etc., but is not an important point in this solution, and therefore, a detailed description is omitted herein.
Illustratively, the flat cable 12 may be an FFC flexible flat cable 12, which plays a role in signal transmission, and is convenient for bending, and is convenient for adapting to the structural design of the main point screen system 11.
Illustratively, the power board 13 is integrated with a current output unit 131, a sampling unit 132 and an ADC conversion unit 133, and the power board 13 is electrically connected to the external display screen 30 to be tested.
In this embodiment, the current output circuit of the MCU controller may be designed asRoad (I)>. Correspondingly, the sampling circuit is +.>Circuit, ADC conversion circuit support->And (5) path conversion. The present embodiment is described by taking 3 paths as an example, and should not be construed as limiting the present application.
Referring to fig. 3, fig. 3 is a circuit diagram of a current output unit 131 employing a cross current output converter MP 3314. The current output unit 131 adopts a cross current output converter MP3314, and is matched with a peripheral circuit, and is correspondingly connected with the SDA port and the SCL port of the MCU controller through the SDA port and the SCL port of the current output unit, so that the MP3314 is communicated with the IIC of the MCU controller, and finally 3 paths of square wave pulse currents (LEDA 1, LEDA2 and LEDA 3) are output under the control of the MCU controller, wherein each element such as a resistor R, a capacitor C, an inductor L, a diode D and the like is marked in the circuit, and detailed description of the circuit is omitted here.
Referring to fig. 4, fig. 4 is a circuit diagram of a sampling unit 132 employing an LMP 8645. The sampling unit 132 adopts the LMP8645 and is matched with a peripheral circuit to realize the sampling and conversion of square wave pulse current and finally output a voltage signal. The voltage signal obtained by sampling and converting the LEDA1 is output through the LED1_I, the voltage signal obtained by sampling and converting the LEDA2 is output through the LED2_I, and the voltage signal obtained by sampling and converting the LEDA3 is output through the LED3_I. The elements are shown in the circuit, and are shown in fig. 4, and the details of the circuit are not described here.
Referring to fig. 5, fig. 5 is a circuit diagram of the ADC conversion unit 133 using the ADS 7828. The ADC conversion unit 133 adopts the ADS7828, and the 3 voltage signals (respectively output through the LED1_ I, LED2_ I, LED3 _3_i) output by the sampling unit 132 may be input through pins 6 to 8 (i.e. CH5, CH6, and CH 7) of the ADS7828, or may be input through other pins by a conversion circuit, which is only an example and not limited herein. With the peripheral circuit, the sampling unit 132 can perform analog-to-digital conversion on the 3 voltage signals to obtain corresponding original ADC measurement values, and the corresponding original ADC measurement values are transmitted back to the MCU controller through the IIC bus (i.e., the signal lines of the SDA port and the SCL port). The elements are shown in the circuit, and are shown in fig. 5, and the details of the circuit are not described here.
Referring to fig. 2 again, the MCU controller may control the current output unit 131 to output a square wave pulse current, the sampling unit 132 samples the square wave pulse current and converts the square wave pulse current into a voltage signal, the ADC conversion unit 133 performs analog-to-digital conversion on the voltage signal to obtain an original ADC measurement value, and transmits the original ADC measurement value back to the MCU controller, and the MCU controller may perform measurement based on the original ADC measurement value to obtain a current detection result and output the current detection result, and the MCU controller may further perform current regulation and overcurrent protection based on the current detection result.
For example, in order to adapt to the current measurement of different display screens, the MCU controller may further obtain the model of the display screen 30 to be measured and send the model to the upper computer 20, search the current parameter (i.e. the backlight current parameter) corresponding to the model of the display screen 30 to be measured through the upper computer 20, then receive the current parameter determined by the upper computer 20 based on the model of the display screen 30 to be measured, and then control the current output unit 131 to output the corresponding square wave pulse current based on the current parameter.
The pulse type direct current sampling measurement device 10 utilizes an MCU controller to control a current output unit 131 to output square wave pulse current, a sampling unit 132 samples the square wave pulse current and converts the square wave pulse current into a voltage signal, an ADC conversion unit 133 performs analog-to-digital conversion on the voltage signal to obtain an original ADC measured value, the original ADC measured value is transmitted back to the MCU controller, the MCU controller performs measurement based on the original ADC measured value to obtain a current detection result and outputs the current detection result, and the MCU controller performs current regulation and overcurrent protection based on the current detection result. The pulse current can be directly measured, and the pulse current can be stably measured without changing hardware when the pulse frequency is controlled to change, so that the pulse current measuring device can be suitable for current detection scenes with different frequencies, can quickly respond when the current is changed, and can realize overcurrent protection. And, can carry on the current regulation and control of feedback type on the basis of the current detection result, help to improve the reliability of detection. By adopting basic circuit devices, the hardware cost can be saved, and the post-maintenance is convenient. Design ofThe circuit detection can be suitable for current detection of different types of display screens (different display screens, the circuit number of the measuring circuit is possibly different), defective products can be accurately detected, the accuracy and the nature of data are improved, the response is quick, and the circuit detection device plays an important role in the detection efficiency and quality control of industrial products.
And through sampling and conversion of the square wave pulse current by the sampling unit 132 and analog-to-digital conversion by the ADC conversion unit 133, the MCU controller may obtain an original ADC measurement value, and for each path of original ADC measurement value, the MCU controller may operate a pulse type dc current measurement method applied to backlight current detection of the display screen to obtain a current detection result.
Referring to fig. 6, fig. 6 is a flowchart of a pulse dc measurement method applied to backlight current detection of a display screen. The pulse type direct current measuring method applied to the backlight current detection of the display screen can comprise the steps of S10, S20, S30, S40 and S50.
First, the MCU controller may run step S10.
Step S10: the method comprises the steps of obtaining an original ADC measured value, wherein the MCU controller controls the current output unit to output square wave pulse current, the sampling unit samples the square wave pulse current and converts the square wave pulse current into a voltage signal, the ADC conversion unit carries out analog-to-digital conversion on the voltage signal to obtain the original ADC measured value, and the ADC conversion unit transmits the original ADC measured value to the MCU controller.
In this embodiment, the MCU controller may obtain each path of raw ADC measurement values, and the specific process may be referred to above.
For example, a fixed interval time acquisition, such as 1ms, may be performed, and a timer is started to count for 100ms (here, taking 100ms as an example, the timing time is only an integer multiple of the square wave frequency, and no attention is paid to an accurate sampling start time), so that 100 sets of data are saved as one path of original ADC measurement values, as shown in fig. 7.
Thereafter, the MCU controller may operate step S20.
Step S20: and carrying out threshold separation on the original ADC measured value to obtain first data.
In this embodiment, the MCU controller may reject the values below the set threshold (e.g., 60) in the original ADC measurement (as shown in fig. 8), and obtain the remaining values (as shown in fig. 9).
The MCU controller may then combine the remaining values to obtain first data, as shown in fig. 10. At this time, since the blank portion is removed (i.e., the portion of the numerical value below the set threshold is filtered out), continuous peak data (i.e., the first data) as shown in fig. 10 can be obtained after the combination, but there is some fluctuation and spike.
Based on this, the MCU controller may run step S30.
Step S30: and sequencing the first data to obtain second data.
In this embodiment, the MCU controller may perform ascending order on all values in the first data to obtain the second data. The second data obtained is shown in fig. 11.
After obtaining the second data, the MCU controller may operate with step S40.
Step S40: and determining a group of undetermined data from the second data, and performing average value calculation to obtain a voltage average value.
In this embodiment, the MCU controller may determine from the second data that the MCU controller is located at the midpointxA number, as pending data, wherein,xthe number of (2) does not exceed the total number of values in the second data. In this embodiment, 10 values at the center are determined as an example.
Then, the MCU controller can calculate the average value of the undetermined data to obtain the voltage average value.
After obtaining the voltage average value, the MCU controller may operate step S50.
Step S50: and calculating a real current value and generating a current detection result based on the voltage average value and ohm law.
In this embodiment, the MCU controller may calculate the actual current value using the following formula using the voltage average value:
， （1）
wherein, the liquid crystal display device comprises a liquid crystal display device,for the true current value, +.>Is the mean value of the voltage>The resistance is known as resistance.
Then, the MCU controller may generate a current detection result including the true current value based on the true current value.
For example, the MCU controller may divide the pending data into a high value group and a low value group based on the voltage average, wherein each value in the high value group is higher than the voltage average and each value in the low value group is lower than the voltage average.
Then, the MCU controller may calculate the average value of the high value group, subtract the average value of the voltage from the average value of the high value group to obtain a voltage floating value, calculate the average value of the low value group, subtract the average value of the low value group from the average value of the voltage to obtain a voltage sinking value. Dividing the floating voltage value by the resistanceThe resistance value of (i.e. the resistance value known when calculating the true current value) to obtain the current float value, and dividing the voltage sink value by the resistance +.>To obtain the current sinking value.
Accordingly, the MCU controller can generate a current detection result comprising a real current value, a current floating value and a current sinking value.
Of course, in other embodiments, the current detection result including the actual current value may be directly generated without calculating the current float value and the current sink value, which is not limited herein.
After the current detection result is determined, the MCU controller can also perform current regulation and overcurrent protection based on the current detection result.
For example, the MCU controller may determine whether the actual current value in the current detection result exceeds the safety threshold. If the true current value exceeds the safety threshold, the MCU controller can shut off the current output to protect the later stage. If the real current value does not exceed the safety threshold, the MCU controller may adjust the square wave pulse current output from the current output unit 131 based on the current detection result.
Specifically, the MCU controller may acquire the current parameter of the display screen 30 to be measured and perform judgment. If the real current value is higher than the current parameter, the MCU controller calculates a first compensation current value based on the following formula:
， （2）
wherein, the liquid crystal display device comprises a liquid crystal display device,for the first compensation current value,/>For the current sinking value, ">For current parameter, +.>Is the true current value.
Accordingly, the MCU controller can subtract the first compensation current value on the basis of the square wave pulse current to obtain the adjusted square wave pulse current and output the adjusted square wave pulse current.
If the real current value is lower than the current parameter, the MCU controller calculates a second compensation current value based on the following formula:
， （3）
wherein, the liquid crystal display device comprises a liquid crystal display device,for the second compensation current value,/>Is the current floating value->For current parameter, +.>Is the true current value.
Accordingly, the MCU controller can add the second compensation current value on the basis of the square wave pulse current, obtain the adjusted square wave pulse current and output the square wave pulse current.
Of course, in other embodiments, in a scene of weak regulation precision, the square wave pulse current can be directly compensated and output based on the difference between the real current value and the current parameter, so as to realize regulation of the square wave pulse current, which is not limited herein.
In summary, the embodiment of the application provides a pulsed dc current measurement method applied to backlight current detection of a display screen, which uses an MCU controller for sampling and measuring the pulsed dc current to control a current output unit 131 to output a square wave pulse current, a sampling unit 132 samples the square wave pulse current and converts the square wave pulse current into a voltage signal, an ADC conversion unit 133 performs an analog-to-digital conversion on the voltage signal to obtain an original ADC measurement value, and transmits the original ADC measurement value back to the MCU controller, and the MCU controller performs measurement based on the original ADC measurement value. Therefore, the pulse current can be directly measured, and the pulse current can be stably measured without changing hardware when the pulse frequency is controlled to change, so that the pulse current measuring device can be suitable for current detection scenes with different frequencies, and can quickly respond when the current is changed. Threshold separation is carried out on the original ADC measured value, and first data are obtained; sequencing the first data to obtain second data; determining a group of undetermined data from the second data, and performing average value calculation to obtain a voltage average value; based on the voltage average value and ohm law, a real current value is calculated and a current detection result is generated. In this way, current measurement with different frequencies can be dealt with, and data in the center of the current after sorting is separated, sorted and selected by using a threshold value as pending data (the group of pending data can well reflect a real current value), the measured current value is closer to the real current value, and detection is more accurate. And the MCU controller can also realize overcurrent protection based on a current detection result, regulate and control the output square wave pulse current, and is beneficial to improving the detection reliability. Based on the voltage average value, the undetermined data are divided into a high value group and a low value group, a voltage floating value and a voltage sinking value are calculated, a current floating value and a current sinking value can be further calculated, and a current detection result containing a real current value, a current floating value and a current sinking value is generated. Judging whether the real current value exceeds a safety threshold value or not; closing the current output to protect the later stage when the safety threshold is exceeded; and if the safety threshold value is not exceeded, the output pulse square wave current is further regulated. The regulation and control mode not only considers the measured real current value, but also considers the influence of the current sinking value and the influence of the current floating value according to the conditions, calculates the corresponding compensation value to carry out compensation regulation and control, so that the regulated and controlled square wave pulse current can quickly and accurately reach the current parameter of the display screen 30 to be tested, the reliability of subsequent detection is improved, and the control of the product quality is improved.
In this document, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions.
The foregoing is merely exemplary embodiments of the present application and is not intended to limit the scope of the present application, and various modifications and variations may be suggested to one skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.
Claims (6)
1. The utility model provides a be applied to pulsed direct current measuring method of display screen backlight current detection which characterized in that, pulsed direct current sampling measuring device includes the main spot screen system of built-in MCU controller and passes through the winding displacement and be connected with MCU controller electricity, the power strip is integrated with current output unit, sampling unit and ADC conversion unit, and the power strip is connected with outside display screen electricity that awaits measuring, the method is applied to the MCU controller includes:
the method comprises the steps that an original ADC measured value is obtained, wherein the MCU controller controls the current output unit to output square wave pulse current, the sampling unit samples the square wave pulse current and converts the square wave pulse current into a voltage signal, the ADC conversion unit carries out analog-to-digital conversion on the voltage signal to obtain the original ADC measured value, and the original ADC measured value is transmitted to the MCU controller by the ADC conversion unit;
threshold separation is carried out on the original ADC measured value to obtain first data;
sequencing the first data to obtain second data;
determining a group of undetermined data from the second data, and performing average value calculation to obtain a voltage average value;
based on the voltage average value and ohm law, calculating a real current value and generating a current detection result;
the method comprises the steps of performing threshold separation on the original ADC measured value to obtain first data, wherein the method comprises the following steps:
removing the values lower than a set threshold value from the original ADC measured value to obtain a residual value; combining the residual values to obtain the first data;
determining a group of undetermined data from the second data, and performing average value calculation to obtain a voltage average value, wherein the method comprises the following steps:
determining from the second data that the data is centeredxA numerical value as the pending data, wherein,xthe number of (2) does not exceed the total number of values in the second dataThe method comprises the steps of carrying out a first treatment on the surface of the And calculating the average value of the undetermined data to obtain the voltage average value.
2. The pulsed dc current measurement method for display screen backlight current detection of claim 1, wherein sequencing the first data to obtain second data comprises:
and carrying out ascending sort on all values in the first data to obtain the second data.
3. The pulsed direct current measurement method applied to display screen backlight current detection according to claim 1, wherein calculating a true current value and generating a current detection result based on the voltage average value and ohm's law comprises:
using the voltage average value, calculating a real current value using the following formula:
，
wherein, the liquid crystal display device comprises a liquid crystal display device,for the real current value, < >>For the voltage mean>Is a resistor with a known resistance value;
based on the true current value, a current detection result including the true current value is generated.
4. A pulsed direct current measurement method for display screen backlight current detection according to claim 3, wherein generating a current detection result containing the true current value based on the true current value comprises:
dividing the undetermined data into a high value group and a low value group based on the voltage average, wherein each numerical value in the high value group is higher than the voltage average, and each numerical value in the low value group is lower than the voltage average;
calculating the average value of the high-value group, subtracting the average value of the voltage from the average value of the high-value group to obtain a voltage floating value, calculating the average value of the low-value group, and subtracting the average value of the low-value group from the average value of the voltage to obtain a voltage sinking value;
dividing the voltage floating value by resistanceTo obtain a current float value, and dividing the voltage sink value by the resistance +.>Obtaining a current sinking value;
generating a current detection result comprising the real current value, the current float value and the current sink value.
5. The method for measuring the pulse-type direct current applied to the backlight current detection of the display screen according to claim 4, wherein after determining the current detection result, the method further comprises:
judging whether the real current value in the current detection result exceeds a safety threshold value or not;
if the real current value exceeds a safety threshold, closing current output to protect a later stage;
and if the real current value does not exceed the safety threshold value, regulating the square wave pulse current output by the current output unit based on the current detection result.
6. The pulsed dc current measurement method for use in display screen backlight current detection according to claim 5, wherein adjusting the square-wave pulse current output by the current output unit based on the current detection result comprises:
acquiring current parameters of a display screen to be tested;
if the true current value is higher than the current parameter, calculating a first compensation current value based on the following formula:
，
wherein, the liquid crystal display device comprises a liquid crystal display device,for the first compensation current value,/>For the current sinking value, ">For current parameter, +.>Is the real current value;
subtracting the first compensation current value on the basis of the square wave pulse current to obtain an adjusted square wave pulse current and outputting the adjusted square wave pulse current;
if the true current value is lower than the current parameter, calculating a second compensation current value based on the following formula:
，
wherein, the liquid crystal display device comprises a liquid crystal display device,for the second compensation current value,/>Is the current floating value->For current parameter, +.>Is the real current value;
and adding the second compensation current value on the basis of the square wave pulse current to obtain and output the adjusted square wave pulse current.
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