An electric energy meter section code liquid crystal screen display self-diagnosis system and method

Abstract

The application relates to the technical field of intelligent electric energy meters, and discloses an electric energy meter segment code liquid crystal screen display self-diagnosis system and method, wherein a power module is connected with a metering module, an MCU (Micro Control Unit) microcontroller main control module, a display module, a communication module and a storage module; the metering module, the communication module and the storage module are all bidirectionally connected with the MCU microcontroller main control module for data interaction; the MCU microcontroller main control module unidirectionally transmits data to the display module through a communication line; a resistance sampling module and a signal amplification module are arranged on the communication line between the MCU microcontroller main control module and the display module; and the signal amplification module is signal-connected with the MCU microcontroller main control module. The circuit is simple, the components are few, the cost advantage is obvious, and the electric energy meter can be used for on-site application; the electric energy meter can timely find whether the liquid crystal screen display of the electric energy meter has an abnormal problem, and the operation reliability of the electric energy meter product is improved.

Description

Technical Field

[0001] This invention relates to the field of smart energy meter technology, specifically to a segment code LCD screen display self-diagnostic system and method for energy meters. Background Technology

[0002] Segment LCD displays have become the mainstream display method for smart energy meters due to their simple operation, low cost, and low power consumption. The LCD screen structure consists of a glass substrate, a liquid crystal layer, and metal pin electrodes. In energy meter applications, the segment LCD screen and the MCU microcontroller (containing an LCD driver module) are mounted together on a PCB board, connected by circuitry and metal pads on the PCB. For signal transmission, the MCU microcontroller unidirectionally sends data signals to the segment LCD screen, which does not respond. Harsh external environments during smart energy meter operation can cause segment LCD screen display failures. In such cases, remote batch troubleshooting via intelligent means is not possible; maintenance personnel must manually inspect each screen on-site. As a legally mandated energy metering device, abnormal segment LCD screen displays in smart energy meters affect users' ability to read normal energy consumption data and thus impact billing. Therefore, this invention provides a self-diagnostic system and method for segment LCD screen displays in energy meters. When an energy meter detects a display fault, it can promptly report the anomaly via a remote data channel, further improving the intelligence level of the energy meter. Summary of the Invention

[0003] The purpose of this invention is to provide a self-diagnostic system and method for displaying segment codes on an electricity meter LCD screen, in order to solve the problems mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a segment code LCD screen display self-diagnostic system for electricity meters, comprising a power supply module, a metering module, an MCU microcontroller main control module, a display module, a communication module, and a storage module. The power supply module is connected to the metering module, the MCU microcontroller main control module, the display module, the communication module, and the storage module. The metering module, the communication module, and the storage module are all bidirectionally interconnected with the MCU microcontroller main control module. The MCU microcontroller main control module transmits data unidirectionally to the display module through a communication line.

[0005] The communication line between the MCU microcontroller main control module and the display module is equipped with a resistance sampling module and a signal amplification module, and the signal amplification module is signal-connected to the MCU microcontroller main control module.

[0006] Preferably, the MCU microcontroller main control module data includes a liquid crystal driving module, which is used to send display content data to the display module.

[0007] Preferably, the resistance sampling module includes a sampling resistor, and the signal amplification module includes an operational amplifier.

[0008] Preferably, the display module includes a segment LCD screen, and the segment LCD screen includes a back electrode interface and a segment electrode interface;

[0009] The MCU microcontroller main control module includes an MCU microcontroller, which includes a memory chip, a comparison unit, an MCU microcontroller back electrode interface, and an MCU microcontroller analog-to-digital conversion interface.

[0010] The memory chip is used to store data, and the comparison unit is used to analyze data differences;

[0011] A sampling resistor is connected in series in the communication line between the LCD screen back electrode interface and the MCU microcontroller back electrode interface; the two input terminals of the operational amplifier are respectively connected to the two ends of the sampling resistor for differential sampling of the voltage difference across the sampling resistor; the output terminal of the operational amplifier is connected to the MCU microcontroller analog-to-digital conversion interface signal.

[0012] This invention also provides a method for a self-diagnostic system for displaying segment codes on an LCD screen of an energy meter, comprising the following steps:

[0013] S1. A sampling resistor is connected in series in the communication line between the back electrode interface of each segment LCD screen and the back electrode interface of the MCU microcontroller. Each sampling resistor is equipped with an operational amplifier, and the two input terminals of each operational amplifier are respectively connected to the two input terminals of the corresponding sampling resistor to perform differential sampling of the voltage difference across the sampling resistor. Then, the output terminal of the operational amplifier is connected to the analog-to-digital conversion interface signal of the MCU microcontroller.

[0014] S2. Write the preset reference signal into the MCU microcontroller memory chip;

[0015] S3. The MCU microcontroller actively sends a command to display the segment LCD screen in full screen. During the full screen display, the MCU microcontroller cyclically collects the current signal on the sampling resistor of each back electrode. The analysis unit compares the signal with a preset reference signal and then determines whether the segment LCD screen is displaying abnormally based on the difference in the compared current signals.

[0016] Preferably, based on the symmetry principle of the operational amplifier differential sampling circuit design, resistors Rc2=Rc3 and Rc4=Rc5, then the formula for calculating the sampling voltage value output by the operational amplifier is: V MCU_ADC = ×(V2-V1)

[0017] Preferably, the preset reference signal includes the standard current value or standard voltage value corresponding to each back electrode when the segment LCD screen is in full-screen display state at the factory, and the current value or voltage value corresponding to one or more segment electrode lines when abnormal.

[0018] Compared with the prior art, the present invention, employing the above technical solution, has the following technical effects:

[0019] A self-diagnostic system and method for segment code LCD screen display of electricity meters is provided. The circuit used in this system and method is simple, with few components, and has obvious cost advantages. For field applications, it can promptly detect whether there are abnormal LCD screen display problems in electricity meters, thereby improving the operational reliability of electricity meter products. Attached Figure Description

[0020] Figure 1 .Structure diagram of a smart energy meter system;

[0021] Figure 2 Schematic diagram of segment code LCD screen display;

[0022] Figure 3 Schematic diagram of the sampling resistor on the back electrode of a segment LCD screen;

[0023] Figure 4 Schematic diagram of operational amplifier differential sampling circuit. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example

[0026] This invention provides a self-diagnostic system for segment code LCD screen displays in energy meters. This system determines whether the display is functioning correctly by detecting minute changes in the operating current of the common terminal and segment electrodes of the segment code LCD screen. This enables the smart energy meter to have a self-diagnostic function.

[0027] The technical solution adopted in this invention is as follows: a sampling resistor is added to the common terminal line connecting the MCU microcontroller (containing an LCD driver module) and the segment LCD screen. The weak current signal of the segment LCD screen during operation is converted into a voltage signal. A high-precision operational amplifier is used to amplify the voltage value on the sampling resistor. The amplified signal is then sent to the MCU microcontroller for further comparison and calculation. The display is judged by the slight change in the operating current.

[0028] The specific technical solution adopted is as follows:

[0029] A segment code LCD screen self-diagnostic system for electricity meters includes a power supply module, a metering module, an MCU microcontroller main control module, a display module, a communication module, and a storage module. The power supply module is connected to the metering module, the MCU microcontroller main control module, the display module, the communication module, and the storage module. The metering module, the communication module, and the storage module are all bidirectionally connected to the MCU microcontroller main control module. The MCU microcontroller main control module transmits data unidirectionally to the display module through the communication line.

[0030] The communication line between the MCU microcontroller main control module and the display module is equipped with a resistance sampling module and a signal amplification module, and the signal amplification module is connected to the MCU microcontroller main control module.

[0031] The MCU microcontroller main control module data includes the LCD driver module, which is used to send display content data to the display module.

[0032] The resistance sampling module includes a sampling resistor, and the signal amplification module includes an operational amplifier.

[0033] The display module includes a segment LCD screen, which includes a back electrode interface and a segment electrode interface.

[0034] The MCU microcontroller main control module includes an MCU microcontroller, which includes a memory chip, a comparison unit, a MCU microcontroller back electrode interface, and an MCU microcontroller analog-to-digital converter (AD) port;

[0035] The memory chip is used to store data, and the comparison unit is used to analyze data differences;

[0036] A sampling resistor is connected in series in the communication line between the LCD screen back electrode interface and the MCU microcontroller back electrode interface. The two input terminals of the operational amplifier are connected to the two ends of the sampling resistor to perform differential sampling of the voltage difference across the resistor. The output terminal of the operational amplifier is connected to the MCU microcontroller's analog-to-digital converter interface. The MCU microcontroller is connected to the communication module to report fault information via a remote data channel when a display abnormality is detected.

[0037] The detailed solution is as follows:

[0038] A smart energy meter consists of six main circuit modules: a power supply module, a metering module, an MCU microcontroller main control module, a display module, a communication module, and a storage module. (System structure diagram follows.) Figure 1As shown, the power supply module converts the 220V AC power line into low-voltage DC power to supply the circuits of each module. The communication module, storage module, and metering module have bidirectional data exchange with the main control module, while the display module and the main control module have unidirectional data exchange; the display content data is sent to the display module by the MCU microcontroller main control module. This solution adds a sampling resistor to the communication line between the MCU microcontroller main control module and the display module. This converts the weak current signal from the LCD screen during operation into a voltage signal. A high-precision operational amplifier amplifies the voltage value across the sampling resistor. The amplified signal is then fed into the MCU microcontroller for further comparison and calculation. The display's functionality is determined by minute changes in the operating current.

[0039] The display principle of a segment LCD screen is to apply an AC voltage between the back electrode (COM) and the segment electrode (SEG). When the voltage difference between the two exceeds a threshold, the corresponding pixel lights up; otherwise, it remains off. Due to the physical properties of the materials used in segment LCD screens, only AC voltage can be applied, not DC voltage. A schematic diagram of a segment LCD screen is shown below. Figure 2 As shown. To illuminate all pixels, a time-division AC voltage needs to be applied between all segment electrodes and the back electrode. If one of the segment electrodes fails to display properly due to external reasons such as poor contact, the back electrode will not be able to collect the operating current during display. This invention utilizes this characteristic for display self-diagnosis.

[0040] Because smart meters need to display a large amount of data, the number of segment electrodes and back electrodes on the segment LCD screen will increase accordingly. Currently, in mainstream designs, the number of segment electrodes ranges from 1 to 50, while the number of back electrodes is available in three specifications: 4, 6, and 8. Since there is a small alternating current between the segment electrodes and the back electrodes during LCD screen operation, a sampling resistor is connected in series between the back electrode of the segment LCD screen and the back electrode of the MCU microcontroller. Figure 3 As shown, when a segment LCD screen displays a signal, a small current will generate a voltage drop across the sampling resistor. An operational amplifier is used to differentially sample this voltage difference across the sampling resistor. The sampled signal is then sent to the analog-to-digital (AD) converter port of the MCU for comparison and calculation. The operational amplifier differential sampling circuit is shown below. Figure 4 As shown.

[0041] As mentioned above, when a segment LCD screen displays a segment, a current path needs to be formed between the corresponding segment electrode and the back electrode before an alternating current can be applied to light up the corresponding pixel. Based on this principle, connecting a sampling resistor in series between each segment electrode between the segment LCD screen and the MCU microcontroller can also achieve the purpose of this invention. However, for the sake of greater rationality, this invention adopts adding a sampling resistor between the back electrodes to reduce the complexity of the circuit design.

[0042] Segment LCD screens consume extremely low current during normal operation, typically in the tens of microamps range. To obtain a reasonable voltage value, the sampling resistor needs to be set to the tens to hundreds of kΩ range. If the sampling resistor is set too large, the displayed strokes will become faint, affecting the display effect. Simultaneously, because the sampled signal amplitude is very small, a high-precision operational amplifier is needed to amplify the sampled signal before sending it to the MCU microcontroller's analog-to-digital converter (AD) port for calculation. Based on the symmetry principle of the operational amplifier differential sampling circuit design, with resistors Rc2=Rc3 and Rc4=Rc5, the formula for calculating the sampled voltage value output by the operational amplifier is: V MCU_ADC = ×(V2-V1). Assuming the sampling resistor is 100kΩ and the current flowing through it during segment LCD display is 1μA, then the sampling voltage V1=V2=I×R=1×100=100mV. Assuming Rc2=100kΩ and Rc4=10kΩ, then the voltage value after amplification by the operational amplifier is V... MCU_ADC = ×(V2-V1)= ×100=1000mV.

[0043] Smart meters are products that operate 24 / 7. During normal operating hours, the LCD screen continuously cycles through the designed data content. Due to the changing displayed content, the alternating current between each segment electrode and the back electrode constantly changes. Furthermore, because the current value of each pixel in the circuit composed of a single segment electrode and the back electrode is small after display, the amount of signal collected is small, which is not conducive to data acquisition and judgment. This invention uses a method where the working current generated on the back electrode after all pixels are lit is superimposed, thereby amplifying the collected signal and improving the accuracy of judgment. In practical applications, the fault self-diagnosis strategy of this invention involves the MCU microcontroller actively sending a full-screen display command to the LCD screen during operation. During full-screen display, the MCU microcontroller cyclically collects the current signal on the sampling resistor of each back electrode. By analyzing the differences in the current signals, it determines whether there is a display abnormality.

[0044] After the MCU microcontroller's analog-to-digital converter (AD) port acquires the changing voltage value, it needs to perform a judgment based on a reasonable judgment strategy. Taking a four-back electrode LCD screen as an example, when the energy meter leaves the factory, the current values ​​on the sampling resistor of the back electrode when the LCD screen is fully displayed are preset to a1, a2, a3, and a4. Each back electrode has its own corresponding segment electrode line. After disconnecting one segment electrode, the current value on the sampling resistor of the back electrode is a1-1, a2-1, a3-1, and a4-1. After disconnecting two segment electrodes, the current value on the sampling resistor of the back electrode is a1-2, a2-2, a3-2, and a4-2. When the back electrode is disconnected, the current value is zero, and so on. The current value after all segment electrode lines are disconnected is preset and written into the MCU microcontroller's storage chip. Subsequently, the current value is used to determine whether the segment code LCD screen is in normal working condition.

[0045] The present invention also provides a method for a self-diagnostic system for a segment code LCD screen display of an energy meter, comprising the following steps:

[0046] S1. A sampling resistor is connected in series in the communication line between the back electrode interface of each segment LCD screen and the back electrode interface of the MCU microcontroller. Each sampling resistor is equipped with an operational amplifier, and the two input terminals of each operational amplifier are respectively connected to the two input terminals of the corresponding sampling resistor to perform differential sampling of the voltage difference across the sampling resistor. Then, the output terminal of the operational amplifier is connected to the analog-to-digital conversion interface signal of the MCU microcontroller.

[0047] S2. Write the preset reference signal into the MCU microcontroller storage chip. The preset reference signal includes the standard current value or standard voltage value corresponding to each back electrode when the segment LCD screen is in full-screen display state at the factory, as well as the current value or voltage value corresponding to one or more segment electrode lines when there is an abnormality.

[0048] S3. The MCU microcontroller actively sends a command to display the segment LCD screen in full screen. During the full screen display, the MCU microcontroller cyclically collects the current signal on the sampling resistor of each back electrode. The analysis unit compares the signal with a preset reference signal and then determines whether the segment LCD screen is displaying abnormally based on the difference in the compared current signals.

[0049] In this case, considering the symmetry principle of the operational amplifier differential sampling circuit design, such that resistors Rc2=Rc3 and Rc4=Rc5, the formula for calculating the sampling voltage value output by the operational amplifier is: V MCU_ADC = ×(V2-V1)

[0050] The MCU microcontroller is also connected to a communication module, which is used to report fault information via a remote data channel when a display abnormality is diagnosed.

[0051] Those skilled in the art will understand that the features described in the various embodiments and / or claims of the present invention can be combined or combined in various ways, even if such combinations or combinations are not explicitly described in the present invention. In particular, the features described in the various embodiments and / or claims of the present invention can be combined or combined in various ways without departing from the spirit and teachings of the present invention. All such combinations and / or combinations fall within the scope of the present invention.

Claims

1. A segment code LCD screen display self-diagnostic system for electricity meters, comprising a power supply module, a metering module, an MCU microcontroller main control module, a display module, a communication module, and a storage module, characterized in that, The power module is connected to the metering module, the MCU microcontroller main control module, the display module, the communication module, and the storage module, respectively. The metering module, the communication module, and the storage module are all bidirectionally connected to the MCU microcontroller main control module. The MCU microcontroller main control module transmits data to the display module unidirectionally through the communication line. The communication line between the MCU microcontroller main control module and the display module is equipped with a resistance sampling module and a signal amplification module, and the signal amplification module is signal-connected to the MCU microcontroller main control module.

2. The segment code LCD screen display self-diagnostic system for electricity meters according to claim 1, characterized in that, The MCU microcontroller main control module data includes a liquid crystal driving module, which is used to send display content data to the display module.

3. The segment code LCD screen display self-diagnostic system for electricity meters according to claim 1, characterized in that, The resistance sampling module includes a sampling resistor, and the signal amplification module includes an operational amplifier.

4. The segment code LCD screen display self-diagnostic system for electricity meters according to claim 3, characterized in that, The display module includes a segment LCD screen, and the segment LCD screen includes a back electrode interface and a segment electrode interface. The MCU microcontroller main control module includes an MCU microcontroller, which includes a memory chip, a comparison unit, an MCU microcontroller back electrode interface, and an MCU microcontroller analog-to-digital conversion interface. The memory chip is used to store data, and the comparison unit is used to analyze data differences; A sampling resistor is connected in series in the communication line between the LCD screen back electrode interface and the MCU microcontroller back electrode interface; the two input terminals of the operational amplifier are respectively connected to the two ends of the sampling resistor for differential sampling of the voltage difference across the sampling resistor; the output terminal of the operational amplifier is connected to the MCU microcontroller analog-to-digital conversion interface signal.

5. A method for a self-diagnostic system for a segment code LCD screen display of an energy meter according to claim 3, characterized in that, Includes the following steps: S1. A sampling resistor is connected in series between the back electrode interface of the LCD screen of each segment LCD screen and the back electrode interface of the MCU microcontroller. Each sampling resistor is equipped with an operational amplifier, and the two input terminals of each operational amplifier are respectively connected to the two input terminals of the corresponding sampling resistor to perform differential sampling of the voltage difference on the sampling resistor. Then connect the output terminal of the operational amplifier to the analog-to-digital converter interface signal of the MCU microcontroller; S2. Write the preset reference signal into the MCU microcontroller memory chip; S3. The MCU microcontroller actively sends a command to display the segment LCD screen in full screen. During the full screen display, the MCU microcontroller cyclically collects the current signal on the sampling resistor of each back electrode. The analysis unit compares the signal with a preset reference signal. Based on the difference in the compared current signals, it determines whether the segment LCD screen is displaying abnormally and reports the fault information through the communication module via the remote data channel.

6. The method for the self-diagnostic system of the segment code LCD screen display of the energy meter according to claim 5, characterized in that, Based on the principle of symmetry in the differential sampling circuit design of the operational amplifier, ensuring that resistors Rc2 = Rc3 and Rc4 = Rc5, the formula for calculating the sampled voltage value output by the operational amplifier is: V MCU_ADC = ×(V2-V1) 7. The method for a self-diagnostic system for a segment code LCD screen display of an energy meter according to claim 5, characterized in that, The preset reference signals include the standard current or standard voltage values ​​corresponding to each back electrode when the segment LCD screen is in full-screen display mode at the factory, as well as the current or voltage values ​​corresponding to one or more segment electrode circuit abnormalities.

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