A digital tube operating status detection system and self-diagnosis method

Abstract

The present invention discloses a digital tube operation state detection system, including a control module, a driving module, a digital tube, a current limiting resistor, a sampling resistor and a current detection module; the 7 output terminals DR0-DR6 of the driving module are respectively electrically connected to the negative pole or positive pole of the a-g segment code of the digital tube; the other end of the a-g segment code of the digital tube is respectively connected to the positive pole or negative pole of the driving power supply through the sampling resistor after being converged through the current limiting resistor; the current detection module is connected in parallel to the sampling resistor, and the output end of the current detection module is electrically connected to the input end of the control module. Therefore, the present invention only uses one sampling resistor and one current detection module to realize effective detection of 7 segment codes in a single digital tube, reduces wiring entanglement, is simple and reliable, can detect segment code level in real time when the digital tube is in normal working state, and saves manual inspection time. The present invention also discloses a digital tube operation state self-diagnosis method based on the above system.

Description

Technical Field

[0001] The invention relates to the field of digital tube detection, and in particular to a digital tube operation state detection system and a self-diagnosis method. Background Art

[0002] LEDs are used in many places to display information, but LEDs can also be damaged. If the damage of LEDs is not known in time in some important occasions, great losses will be caused.

[0003] The existing technology for LED testing is mainly concentrated in the quality inspection link before leaving the factory. Since it is a batch test, the complexity of the testing equipment is not required to be high.

[0004] However, when testing the operating conditions of LEDs during use, the detection device cannot be too complicated and too much wiring cannot be added.

[0005] At present, there are three main types of detection technologies for LED operation:

[0006] 1. Voltage and current detection method: The operation status of the LED is judged by detecting the voltage on both sides of the LED or the current flowing through the LED when the LED is lit; as introduced in the Chinese patent with application number 201910155444.5, a sampling resistor is set on the drive circuit, and then each LED is lit one by one through instructions, and compared with the theoretical value of the current provided by the drive system to judge the operation status of the LED. The structure is complex and the detection process is cumbersome. The display screen can only be stopped for special detection. It is suitable for factory detection and maintenance detection, but not suitable for detection during daily use of LED.

[0007] For the simultaneous detection during the daily use of LED, the following methods are generally used:

[0008] 2. Photoelectric detection method: by setting photoelectric sensors at the positions corresponding to the LEDs, the operation of the LEDs can be detected. This method is only applicable when there are fewer LEDs. If there are more LEDs, each LED or each LED combination of one segment needs to be configured with a photoelectric sensor. Each digital tube includes seven segments, so seven photoelectric sensors are required. The seven-segment code drive wiring and the seven-segment code detection wiring are more and will be entangled and crossed, affecting the system's anti-electromagnetic interference performance. At the same time, the photoelectric detection method is easily affected by ambient light and reduces the judgment accuracy.

[0009] 3. Image detection method, by taking pictures of the LED display device and further analyzing the pictures to detect the operation of the LED. This method is more complicated, involves complex image processing technology, and is very costly.

[0010] In summary, the existing current and voltage methods are mostly used for production inspection devices, and are not real-time operation process detection. Similar methods include LED dot matrix screen detection, which is based on dynamic scanning drive, multi-channel time-sharing voltage and current detection, and cyclic detection of a certain line in a multi-line display. The detection control circuit is complex and costly, and is not very practical for digital LED operation status detection.

[0011] The photoelectric method senses and detects the photoelectric conversion of each segment of the digital LED. There are many switching devices and wiring, which increases the potential for failure and easily leads to misjudgment.

[0012] The image method requires an external camera, which is not practical for use in digital LED clocks and other occasions.

[0013] Therefore, those skilled in the art are in urgent need of a system and method with low cost, simple structure and online real-time detection of the display status of digital tubes. Summary of the invention

[0014] The technical problem to be solved by the present invention is to provide a digital tube operating status detection system.

[0015] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0016] A digital tube operation status detection system comprises a control module and at least one group of display measurement components, each group of display measurement components comprises a driving module, a digital tube, a current limiting resistor, a sampling resistor and a current detection module.

[0017] The driving module includes 7 output terminals DR0-DR6, and the digital tube includes 7 segments ag. The 7 output terminals DR0-DR6 of the driving module are respectively electrically connected to the negative electrode of the ag segment of the digital tube or respectively electrically connected to the positive electrode of the ag segment of the digital tube, so as to simultaneously drive each segment on the digital tube to emit light;

[0018] The positive electrodes of the ag segments of the digital tubes are electrically connected to a current limiting resistor respectively; the other end of each current limiting resistor is connected in parallel and then electrically connected to one end of the sampling resistor, and the other end of the sampling resistor is connected to the positive electrode or the negative electrode of the driving power supply;

[0019] The current detection module is connected in parallel to the sampling resistor, and the output end of the current detection module is electrically connected to the input end of the control module;

[0020] The control module stores the standard current values ​​of all characters that can be displayed by the digital tube. By comparing the current measured by the current detection module with the internally stored standard current value, it can be known whether the digital tube is working normally.

[0021] Based on the above technical solution, the present invention can also be improved as follows.

[0022] Preferably, the current detection module adopts a high-end current detection chip or a low-end current detection chip;

[0023] Preferably, the high-end current detection chip is a MAX4173 series product;

[0024] Preferably, the control module adopts a SOC type single chip microcomputer or an ARM microcontroller, and the SOC refers to a system on chip (System on Chip), which itself has the most basic functions required by the system;

[0025] Preferably, the SOC type single chip microcomputer adopts PIC16F887;

[0026] Preferably, the current detection module uses a current monitor with serial digital output; the current monitor with serial digital output has an AD conversion function itself and can transmit data through a data bus, which can further reduce the amount of wiring when multiple digital tubes are used simultaneously.

[0027] Preferably, the serial digital output current monitor is INA219 from TI;

[0028] Preferably, the driving module adopts TPIC6B595;

[0029] Compared with the prior art, the present invention has the following technical effects:

[0030] For each static or improved static driven digital tube LED, intensive current detection of 7 segments from a to g is performed in real time. By comparing with the standard current memorized in the control unit, the faulty digital tube and specific segment code can be diagnosed and sent back to the control module for further processing.

[0031] Only one sampling resistor and one current detection module are needed to effectively detect the seven segments in a single digital tube. This is simple and reliable, and can perform real-time segment-level detection when the digital tube is working normally. There is no need to enter a special maintenance mode for detection, thus saving inspection and maintenance time.

[0032] The invention also discloses a digital tube operating state self-diagnosis method based on the above detection system.

[0033] The detection steps are as follows:

[0034] S1 establishes a standard ammeter in the control module

[0035] S1-1, start the system;

[0036] S1-2, the control module controls the digital tube to display the preset characters in sequence;

[0037] S1-3, the current detection module detects the voltage value of the sampling resistor at both ends in real time when the current character is displayed, and forms a standard ammeter, in which each displayed character corresponds to a standard current; S2, detects the running status of the digital tube

[0038] S2-1, the control module detects the working current of the digital tube in real time;

[0039] S2-2, comparing the real-time current of the displayed character with the standard current value of the corresponding character in the standard current table, if the deviation exceeds the set threshold, go to step S2-3, otherwise go to step S2-1;

[0040] S2-3, the control module records the characters displayed when the current of multiple digital tubes is abnormal, and combines the segment code truth table of the displayed characters. The segment codes included in the characters displayed when the current is abnormal are the segment codes of the specific faults;

[0041] S3. The control module issues a warning message to the outside.

[0042] On the basis of the above, this method can also be improved as follows:

[0043] Furthermore, in step S3, the control module issues a warning message to the outside, specifically, the control module controls the digital tube to flash and display, and issues a warning message of display abnormality to the outside.

[0044] The flashing display of the digital tube provides warning information to the outside world to prevent the outside world from receiving wrong information. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is a circuit schematic diagram for detecting the operating status of a single digital tube in Example 1;

[0046] Figure 2 This is a schematic diagram of the segment code distribution in a single digital tube;

[0047] Figure 3 This is a schematic diagram of the status of the digital tube displaying characters 0-9;

[0048] Figure 4 This is the segment code truth table corresponding to the digital tube displaying characters 0-9;

[0049] Figure 5 This is a circuit schematic diagram of Example 2 when multiple digital tubes are used simultaneously;

[0050] Figure 6 This is a circuit schematic diagram of Example 3 when multiple digital tubes are used simultaneously;

[0051] Figure 7 The internal structure principle diagram of the segment code a of the digital tube in the embodiment;

[0052] Figure 8 It is a flow chart of the self-diagnosis method of the digital tube operation status of the present invention;

[0053] Fig. 9 It is a schematic diagram of the state of a single segment code of the digital tube in the embodiment when it is working normally;

[0054] Fig.10 This is a schematic diagram of a short-circuit fault of an LED in a single segment of a digital tube in the embodiment;

[0055] Fig.11 It is a schematic diagram of an open circuit failure of an LED in a single segment of a digital tube in the embodiment. DETAILED DESCRIPTION

[0056] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0057] Embodiment 1:

[0058] Please refer to Figure 1 As shown, a digital tube operation status detection system includes a control module mainly composed of PIC16F887, and a group of display measurement components, wherein the display measurement components include a driving module TPIC6B595, a digital LED1, a current limiting resistor Ra-Rg, a sampling resistor R1 and a current detection module MAX4173.

[0059] The RB0 end of the control module is electrically connected to the SERIN end of the driving module TPIC6B595; the RB1 end of the control module is electrically connected to the SRCK end of the driving module TPIC6B595 to provide a shift register clock signal for the driving module; the RB2 end of the control module is electrically connected to the RCK end of the driving module TPIC6B595 to provide a storage register clock signal for the driving module; the RC2 end of the control module is electrically connected to the The terminal is used to provide the output enable signal of the driver module; the driver module TPIC6B595 The terminal is connected to the power supply Vcc.

[0060] The driving module TPIC6B595 includes 7 output terminals DR0-DR6, and the digital tube LED1 includes 7 segments ag. The 7 output terminals DR0-DR6 of the driving module are electrically connected to the negative electrodes of the segments ag of the digital tube, that is, DR0 is connected to the a terminal of LED1, DR1 is connected to the b terminal of LED1, and so on, for simultaneously driving the segments on the digital tube LED1 to emit light;

[0061] The positive electrodes of the ag segments of the digital tube are electrically connected to a current limiting resistor, that is, the a1 end of the digital LED1 is connected to the current limiting resistor Ra, the b1 end is connected to the current limiting resistor Rb, and so on, the g1 end is connected to the current limiting resistor Rg, and the other ends of the current limiting resistors Ra to Rg are connected in parallel and electrically connected to one end of the sampling resistor R1, and the other end of the sampling resistor R1 is connected to the positive electrode of the driving power supply;

[0062] The input terminal RS+ of the current detection module MAX4173 is connected to the positive electrode of the driving power supply, RS- is connected to the non-driving power supply terminal of the sampling resistor R1, and the output terminal Vout of the current detection module MAX4173 is electrically connected to an analog-to-digital conversion input terminal RA0 of the control module PIC16F887;

[0063] The control module PIC16F887 stores a standard ammeter, which refers to the standard current value corresponding to when all segments of the digital tube LED1 display normal and the digital tube LED1 displays preset characters. By comparing the real-time current measured by the current detection module with the internally stored standard current value, the working status of the digital tube can be known.

[0064] This solution only adds a sampling resistor R1 and a high-end current detection module MAX4173 to the existing digital tube display circuit, which can detect the operation of the digital tube LED1 in real time. The circuit is compact and the operation is stable and reliable. Compared with the low-end current detection module, the high-end current detection module is more stable and the current detection is more accurate.

[0065] Embodiment 2:

[0066] Example 2 Figure 5 As shown, it includes multiple display measurement components, which are controlled by a control module PIC16F887 at the same time. Each display measurement component includes a digital tube driving module TPIC6B595, a digital LED, a group of current limiting resistors, a sampling resistor and a current detection module MAX4173. The SEROUT of the digital tube driving module TPIC6B595 in the first display measurement component is electrically connected to the SERIN end of the digital tube driving module TPIC6B595 in the second display measurement component, and the same is true for cascading. The current detection module of each display measurement component is respectively connected to an input end of the control module PIC16F887. Since the display of each display measurement component is controlled by the control module, each display measurement component corresponds to a sampling resistor separately, and the voltage information at both ends of each sampling resistor is respectively sent to an input end of the control module, so that the control module can process them separately, thereby realizing real-time segment code level detection of the display state of each digital tube.

[0067] Embodiment 3:

[0068] Different from Example 2, in this embodiment, the current detection module in the display measurement component adopts INA219 of TI. INA219 itself has AD conversion function, can transmit data through the data bus, and can program the address. The SDA end of each current detection module INA219 is connected in parallel to the RC4 end of the control module, and the SCL end of each current detection module INA219 is connected in parallel to the RC3 end of the control module. By setting the A0 end and A1 end of the current detection module INA219, each current detection module has a different address. The control module can access and read the value of a specific current detection module through different addresses, thereby realizing the detection function of the operating status of multiple digital tubes with less wiring.

[0069] The present invention discloses a method for self-diagnosis of the operation status of a digital tube. Figure 8 As shown, based on the above detection system. The steps are as follows:

[0070] S1 establishes a standard ammeter in the control module

[0071] S1-1, start the system;

[0072] S1-2, the control module controls the digital tube to display the preset characters in sequence;

[0073] S1-3, the current detection module detects the voltage value of the sampling resistor at both ends in real time when the current character is displayed, and forms a standard ammeter, in which each displayed character corresponds to a standard current; S2, detects the running status of the digital tube

[0074] S2-1, the control module detects the working current of the digital tube in real time;

[0075] S2-2, comparing the real-time current of the displayed character with the standard current value of the corresponding character in the standard current table, if the deviation exceeds the set threshold, go to step S2-3, otherwise go to step S2-1;

[0076] S2-3, the control module records the characters displayed when the current of multiple digital tubes is abnormal, and combines the segment code truth table of the displayed characters. The segment code contained in multiple characters is the segment code of the specific fault;

[0077] S3, the control module controls the digital tube to flash and display, and sends a display abnormality warning message to the outside world.

[0078] Taking the clock field to display the numbers 0-9 as an example, the segments of the digital tube are as follows Figure 2 As shown in the definition, the digital tube displays the status of 0-9 as follows Figure 3 As shown, the corresponding segment code truth table when the digital tube displays characters 0-9 is as follows Figure 4 As shown, Figure 4 In the figure, 0 indicates that the corresponding segment code is off, and 1 indicates that the corresponding segment code is on.

[0079] like Figure 7 As shown in the figure, a single segment of the digital tube is composed of two groups of light-emitting diodes in parallel, each group includes 3 light-emitting diodes connected in series, the driving power supply of a single segment is 7.8V, the sampling resistor is 4.7 ohms, and the current limiting resistor of each LED string is 100 ohms. When the LED is normally lit, Fig. 9 As shown, the working current flowing through the sampling resistor R1 is 30mA, that is, the standard current value is 30mA; if a single LED in the segment code is short-circuited, such as Fig.10 As shown, the measured working current flowing through the sampling resistor R4 reaches about 45mA, which is 1.5 times the standard current value. If a single LED in the segment code is open circuited, Fig.11 As shown, the actual working current flowing through the sampling resistor is about 15mA, which is 50% of the standard current value.

[0080] When only one segment code fails, if the control module detects that the current value exceeds the set threshold when displaying characters 0, 2, 3, 5, 6, 7, 8, and 9, but is normal when displaying characters 1 and 4, it can be determined that segment code a on the digital tube is abnormal;

[0081] If the current value exceeds the set threshold when displaying characters 0, 1, 2, 3, 4, 7, 8, and 9, but is normal when displaying characters 5 and 6, it can be determined that segment code b on the digital tube is abnormal;

[0082] Combined with the difference between the actual current value and the standard current value in the above short circuit and open circuit conditions, and combined with Figure 4 The truth table shown can be used to deduce the fault condition of each specific segment code through a limited number of logical reasonings, making the fault location more accurate.

[0083] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A self-diagnosis method for the operation status of a digital tube, characterized in that: The self-diagnosis method adopts a digital tube operation status detection system, which includes a control module and at least one group of display measurement components, each group of display measurement components includes a driving module, a digital tube, a current limiting resistor, a sampling resistor and a current detection module; The driving module includes 7 output terminals DR0-DR6, the digital tube includes 7 segments ag, and the 7 output terminals DR0-DR6 of the driving module are respectively electrically connected to the negative electrode of the ag segment of the digital tube or respectively electrically connected to the positive electrode of the ag segment of the digital tube; The other end of the ag segment code of the digital tube is respectively connected through a current limiting resistor; and then connected to the positive electrode or negative electrode of the driving power supply through a sampling resistor; The current detection module is connected in parallel to the sampling resistor, and the output end of the current detection module is electrically connected to the input end of the control module; The detection steps are as follows: S1. Establish a standard ammeter in the control module; S1-1, start the system; S1-2, the control module controls the digital tube to display the preset characters in sequence; S1-3, the current detection module detects the voltage value of the two ends of the sampling resistor in real time when the current character is displayed, and forms a standard ammeter, in which each displayed character corresponds to a standard current; S2, detect the running status of the digital tube; S2-1, the control module detects the working current of the digital tube in real time; S2-2, comparing the real-time current of the displayed character with the standard current value of the corresponding character in the standard current table to determine whether the deviation exceeds the set threshold. If the deviation exceeds the set threshold, go to step S2-3, otherwise return to step S2-1; S2-3, the control module records the characters displayed when the current of multiple digital tubes is abnormal, and combines the segment code truth table of the displayed characters. The segment codes included in the characters displayed when the current is abnormal are the segment codes of the specific faults; S3. The control module issues a warning message to the outside.

2. A digital tube operating status self-diagnosis method according to claim 1, characterized in that: The current detection module adopts a high-end current detection chip or a low-end current detection chip.

3. A digital tube operating status self-diagnosis method according to claim 2, characterized in that: The high-end current detection chip is MAX4173.

4. A digital tube operating state self-diagnosis method according to any one of claims 1 to 3, characterized in that: The control module adopts a single chip microcomputer or an ARM microcontroller.

5. A digital tube operating status self-diagnosis method according to claim 4, characterized in that: The single chip microcomputer is PIC16F887.

6. A digital tube operating status self-diagnosis method according to claim 1 or 2, characterized in that: The current detection module adopts a current monitor with serial digital output.

7. A digital tube operating status self-diagnosis method according to claim 6, characterized in that: The serial digital output current monitor is INA219 from TI.

8. A digital tube operating status self-diagnosis method according to claim 1, characterized in that: The driving module adopts TPIC6B595.

9. A digital tube operating status self-diagnosis method according to claim 1, characterized in that: The step S3 controls the module to send a warning message to the outside, specifically, the control module controls the digital tube to flash and send a warning message of display abnormality to the outside.

Images