Digital tube self-diagnosis and repair system, method and time display device

Abstract

The present invention relates to the field of digital tubes, and specifically to a digital tube self-diagnosis and repair system, method and time display device. It includes a power supply module; a self-diagnosis module, the self-diagnosis module includes a main position control decoder, a standby position control decoder, a main segment control shift register, a standby segment control shift register, and an N-bit digital tube, the digital tube is composed of 7 segment codes, each segment code is composed of two segments of LED strings, the main segment LED string is used for normal display, and the standby segment LED string is used for standby display; an MCU control module, first using the main segment control shift register and the standby segment control shift register to perform segment selection, and then using the main position control decoder and the standby position control decoder to realize bit selection, and automatically switching to the standby segment LED string after detecting that the voltage at the test end of the main segment LED string exceeds the threshold range. The beneficial effects of the present invention are fast positioning speed of fault segment code, accurate positioning, simple algorithm, fast response, and no need for external components.

Description

Technical Field

[0001] The invention relates to the field of digital tubes, and in particular to a digital tube self-diagnosis and repair system, method and time display device. Background Art

[0002] As a new type of light source that is earthquake-resistant, energy-saving, environmentally friendly and efficient, LED has been increasingly widely used in all aspects of people's lives. Digital tubes are used as clock display units to display hours, minutes and seconds and provide time services. Once a digital tube has a short circuit or open circuit during operation, it cannot display time information correctly, causing many inconveniences in life and affecting normal use.

[0003] In response to the above problems, patent number CN211402621U discloses a digital tube operation status detection system. 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 standard current value stored internally, it can be known whether the digital tube is working normally. The digital tube LED is subjected to intensive current detection of 7 segments from a to g in real time. By comparing it with the standard current memorized in the control unit, the faulty digital tube and specific segment code can be diagnosed and transmitted back to the control module for further processing.

[0004] This detection algorithm software is difficult and complex to implement. Although it can theoretically locate the faulty segment code, it requires multiple reasoning and comparisons, and the positioning efficiency is low. In addition, it only issues an alarm message through the flashing of the digital tube, and no solution is proposed. In the prior art, when an LED is damaged, it is first necessary to detect the faulty segment code, and then it is often necessary to stop the operation and replace the component, which affects the normal display and requires a large amount of maintenance work. Summary of the invention

[0005] In order to solve the above technical problems, the purpose of the present invention is to provide a digital tube self-diagnosis and repair system, method and time display device, which can detect faulty segment codes online in real time and repair them in time.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] A digital tube self-diagnosis and repair system, comprising:

[0008] A power module, used for supplying power to the self-diagnosis and repair system;

[0009] A self-diagnosis module, the self-diagnosis module includes a main position control decoder, a standby position control decoder, a main segment control shift register, a standby segment control shift register, and an N-bit digital tube, N is an integer greater than or equal to 1, wherein: the digital tube is composed of 7 segment codes, each of the segment codes is composed of two segments of LED strings, the main segment LED string is used for normal display, and the standby segment LED string is used for standby display, the output ends of the main position control decoder and the main segment control shift register are electrically connected to the main segment LED string, and the output ends of the standby position control decoder and the standby segment control shift register are electrically connected to the standby segment LED string;

[0010] The MCU control module first uses the main segment control shift register and the standby segment control shift register to perform segment selection, and then uses the main position control decoder and the standby position control decoder to realize position selection. After the MCU control module detects that the voltage at the test end of the main segment LED string exceeds the threshold range, it automatically switches to the standby segment LED string to work.

[0011] Preferably, the digital tube adopts a common anode connection mode;

[0012] Each output end of the main segment control shift register is respectively connected to the base of the corresponding main segment triode, the collector of the main segment triode is connected to the negative electrode of the main segment LED string, the emitter of the main segment triode is connected to the first end of the main segment resistor, the second end of the main segment resistor is grounded, and the emitter of the main segment triode leads to the test end PA and is connected to the AD sampling end of the MCU control module;

[0013] Each output end of the standby segment control shift register is respectively connected to the base of the corresponding standby segment triode, the collector of the standby segment triode is connected to the cathode of the standby segment LED string, the emitter of the standby segment triode is connected to the first end of the standby segment resistor, and the second end of the standby segment resistor is grounded;

[0014] Each output terminal of the master control decoder is connected to the base of the corresponding master transistor, the collector of the master transistor is connected to the positive electrode of the M main segment LED strings, and the emitter of the master transistor is connected to the power supply VCC;

[0015] Each output end of the standby control decoder is connected to the base of the corresponding standby transistor, the collector of the standby transistor is connected to the positive electrode of the M standby LED strings, and the emitter of the standby transistor is connected to the power supply VCC.

[0016] Preferably, each output end of the main-segment control shift register is respectively connected to one end of the corresponding base resistor R3, the other end of the base resistor R3 is connected to the base of the main-segment transistor, the emitter of the main-segment transistor is connected to the resistor R4 and the main-segment resistor R5, the other end of the main-segment resistor R5 is grounded, and the other end of the resistor R4 leads to the test end PA, the test end PA is electrically connected to the power supply VCC′ through the switching diode, and is grounded through the capacitor C1.

[0017] The present invention also provides a digital tube self-diagnosis and repair method, which is characterized by comprising:

[0018] S1, initialize the circuit power-on;

[0019] S2, determine whether the first digital tube fault flag is zero, if yes, go to S4, if no, go to S3;

[0020] S3, the fault segment code switches to the standby segment LED string to work;

[0021] S4, displaying the characters preset by the digital tube;

[0022] S5, detect whether the voltage value of the test terminal PA of each segment of the next digital tube exceeds the threshold;

[0023] S6. Determine whether there is a fault, fault segment code, and fault type through the voltage threshold range;

[0024] S7. If there is no fault, proceed to step S4; if there is a fault, proceed to step S3.

[0025] Preferably, when a fault is detected in a main segment LED string of a certain segment code of the digital tube, an alarm message is uploaded to display the fault segment code and the fault type.

[0026] Preferably, the voltage threshold range includes an open circuit voltage threshold range and a short circuit voltage threshold range.

[0027] Preferably, the circuit breaker voltage threshold range is that the voltage value of the test terminal PA is between 0.05V and 0.5V.

[0028] Preferably, the short-circuit voltage threshold range is that the voltage value of the test terminal PA is greater than U1-U2-U3-(mn)U4+ΔU. Where:

[0029] The value of the power supply VCC is U1, the saturation voltage drop of the main stage transistor is U2, the saturation voltage drop of the main position transistor is U3, the main stage LED string is composed of m light-emitting diodes connected in series, n is the number of light-emitting diodes that are short-circuited, m and n are integers greater than 1, and n is less than or equal to m, the voltage drop of a single light-emitting diode is U4, and ΔU is the correction coefficient.

[0030] The present invention also provides a digital tube time display device, comprising the digital tube self-diagnosis and repair system.

[0031] Preferably, the digital tube time display device uses an 8-bit digital tube, and the 7 segments of each digital tube are arranged in a day shape to display hours, minutes, colons between hours and minutes, seconds, and colons between minutes and seconds.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1) The MCU control system detects the voltage value of the test end of each segment code in real time, monitors the fault segment code and fault type, and locates the fault segment code quickly and accurately.

[0034] 2) Each segment code is composed of two LED strings. When a failure occurs in the main segment LED string of a certain segment code, the system can switch to the backup segment LED string in time without affecting the normal time display of the digital tube.

[0035] 3) When the fault segment code is switched to the standby LED string, the alarm information is uploaded to display the fault segment code and fault type, so as to facilitate the selection of the appropriate time for maintenance later.

[0036] 3) The digital tube self-diagnosis and repair method of the present invention has a simple algorithm, a fast response, and does not require any external components. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0038] Figure 1 This is a circuit diagram of a digital tube self-diagnosis and repair system according to an embodiment of the present invention;

[0039] Figure 2 It is a schematic diagram of the circuit connection mode of the main segment LED string in the segment code of the digital tube of the embodiment of the present invention;

[0040] Figure 3 Schematic diagram of a digital tube time display device according to an embodiment of the present invention;

[0041] Figure 4 The present invention is a flowchart of a self-diagnosis and repair method for a digital tube time display device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0042] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0043] In the description of the present invention, unless otherwise clearly specified and limited, if the term "connection" or the like appears to indicate the connection relationship between components, the term should be understood in a broad sense, for example, it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two components or the interaction relationship between two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] like Figure 1 The self-diagnosis and repair system of a digital tube shown in the figure includes: a power module for supplying power to the self-diagnosis system, a self-diagnosis module and an MCU control module, the self-diagnosis module includes a main position control decoder SM74HC138, a standby position control decoder SM74HC138, a main segment control shift register 74HC595D, a standby segment control shift register 74HC595D, and N-bit digital tubes, each digital tube consists of 7 segment codes a to g, N is an integer greater than 1, Figure 1 This is only a single-digit digital tube circuit connection diagram. The connection methods of other digital tubes are similar. The number of digital tubes can be any number within the controllable range of the output end of the decoder of this circuit.

[0045] Each segment code of the digital tube is composed of two segments of LED strings. The main segment LED string is used for normal display, and the backup segment LED string is used for backup display. The LED string is composed of several LEDs in series. The number of LEDs can be adjusted according to the specific application. When the MCU control module detects that the voltage at the test end of the main segment LED string exceeds the threshold range, it automatically switches to the backup segment LED string to work.

[0046] The digital tube adopts a common anode connection mode, and each output end of the main segment control shift register 74HC595D is respectively connected to the base of the corresponding main segment transistor Qa, the collector of the main segment transistor Qa is connected to the cathode of the main segment LED string, the emitter of the main segment transistor Qa is connected to the first end of the main segment resistor Ra and the A / D sampling end of the MCU control module, and the second end of the main segment resistor Ra is grounded.

[0047] The number of working output terminals of each main segment control shift register 74HC595D is consistent with the number of main segment transistors Qa and the number of digital tube segment codes, that is, if the digital tube contains 7 segment codes, the 7 output terminals of the main segment control shift register 74HC595D need to work, and each working output terminal is connected to a main segment transistor.

[0048] The main segment control shift register preferably adopts 74HC595D, and may also be other shift registers / latch that can realize the segment selection function.

[0049] Each output end of the standby control shift register 74HC595D is respectively connected to the base of the corresponding standby transistor Qa′, the collector of the standby transistor Qa′ is connected to the cathode of the standby LED string, the emitter of the standby transistor Qa′ is connected to the first end of the standby resistor Ra′, and the second end of the standby resistor Ra′ is grounded.

[0050] The number of working output terminals of each spare segment control shift register 74HC595D is consistent with the number of spare segment transistors Qa′ and the number of digital tube segment codes, that is, if the digital tube contains 7 segment codes, the 7 output terminals of the spare segment control shift register 74HC595D need to work, and each working output terminal is connected to a spare segment transistor Qa′.

[0051] The standby segment control shift register preferably adopts 74HC595D, and may also be other shift registers / latch that can realize the segment selection function.

[0052] The output ends of the master control decoder SM74HC138 are respectively connected to the bases of the corresponding master transistors Q1, the collectors of the master transistors Q1 are connected to the positive electrodes of the master LED strings, and the emitters of the master transistors Q1 are connected to the power supply VCC.

[0053] The number of working output terminals of each main position control decoder SM74HC138 is consistent with the number of main position transistors Q1 and the number of digital tubes N. That is, if 3-digit digital tubes are controlled, the three output terminals of the main position control decoder need to work, and each working output terminal is connected to a main position transistor Q1.

[0054] The main bit control decoder preferably adopts SM74HC138, and other decoders capable of realizing the bit selection function may also be adopted.

[0055] Each output terminal of the standby control decoder SM74HC138 is connected to the base of the standby transistor Q1', the collector of the standby transistor Q1' is connected to the positive electrode of the standby LED string, and the emitter of the standby transistor Q1' is connected to the power supply VCC.

[0056] The number of working output terminals of each standby control decoder SM74HC138 is consistent with the number of standby transistors Q1′ and the number of digital tubes N. That is, if it is a 3-digit digital tube, the three output terminals of the standby control decoder need to work, and each working output terminal is connected to a standby transistor Q1′.

[0057] The standby bit control decoder preferably uses SM74HC138, and other decoders that can realize the bit selection function can also be used.

[0058] Figure 1The embodiment shown is a digital tube that adopts a common anode connection mode. Under the concept of the present invention, the digital tube can also adopt a common cathode connection mode, and the circuit connection mode is slightly deformed, which will not be repeated here.

[0059] The MCU control module preferably uses STM32F103RCT6, and other single-chip microcomputers that can realize the control function can also be used. The digital tube display device containing the above self-diagnosis and repair system displays information through dynamic scanning, first segment selection and then bit selection. The MCU control module uses 74HC595D shift register / latch to realize segment selection. The output end of 74HC595D is respectively connected to the 7 segment codes of the digital tube, and the corresponding high and low levels are sent to realize the corresponding display. The MCU control module realizes bit selection by controlling the SM74HC138 decoder. The truth table of SM74HC138 is shown in Table 1 below. When E3 is connected to low level, low level, and high level respectively, the MCU can make The working end outputs a unique low level, so that only the transistor of a certain digit in the digital tube is in the on state, and the rest are in the off state, thus realizing the display of a certain digit of the digital tube.

[0060] Table 7 Truth table of SM74HC138 decoder

[0061]

[0062]

[0063] Note: H represents high level, L represents low level, and × represents any level

[0064] STM32F103RCT6 uses ADC to sample the voltage value of the test terminal PA of each segment code main segment LED string, and determines whether the main segment LED string has a short circuit or open circuit fault by measuring the voltage threshold range of the test terminal PA. Once a fault is detected, the segment code immediately enables the spare segment LED string to display the time to ensure normal use.

[0065] Preferably, the test end PA circuit is further improved, such as Figure 3 As shown, the output end of the main segment control shift register 74HC595D is connected to one end of the base resistor R3, the other end of the base resistor R3 is connected to the base of the main segment transistor Qa, the emitter of the main segment transistor 2 is connected to the resistor R4 and the main segment resistor R5, the other end of the main segment resistor R5 is grounded, and the other end of the resistor R4 leads to the test terminal PA, the test terminal PA is electrically connected to the power supply VCC′ through the switching diode and is grounded through the capacitor C1.

[0066] The base of the master transistor Q1 is electrically connected to the output end of the master control decoder SM74HC138 through the resistor R1, and the resistor R2 is connected between the emitter and the base of the transistor 1.

[0067] A digital tube self-diagnosis and repair method is provided for the digital tube self-diagnosis and repair system of the present invention, comprising the following steps:

[0068] S1, initialize the circuit power-on;

[0069] S2, determine whether the first digital tube fault flag is zero, if it is, go to S4, if not, go to S3;

[0070] S3, the fault segment code switches to the standby segment LED string to work;

[0071] S4, displaying the characters preset by the digital tube;

[0072] S5, detect the voltage value of the main segment LED string test terminal PA of each segment code of the next digital tube;

[0073] S6, judging whether the voltage value of each segment code test terminal PA exceeds the threshold;

[0074] S7, judging whether there is a fault, fault segment code, and fault type through the voltage threshold range;

[0075] S8, if there is no fault, proceed to step S4, if there is a fault, proceed to step S3;

[0076] Furthermore, when a fault is detected in a main segment LED of a certain segment code, an alarm message is uploaded to display the fault segment code and the fault type.

[0077] The voltage threshold range includes an open circuit voltage threshold range and a short circuit voltage threshold range. The open circuit voltage threshold range is that the voltage value of the test terminal PA is between 0.05V and 0.5V, and the short circuit voltage threshold range is that the voltage value of the test terminal PA is greater than U1-U2-U3-(mn)U4+ΔU. Wherein: the value of VCC is U1, the saturation voltage drop of transistor 1 is U2, the saturation voltage drop of transistor 2 is U3, the main segment LED string is composed of m light-emitting diodes connected in series, n is the number of short-circuited light-emitting diodes, m and n are integers greater than 1, and n is less than or equal to m, the voltage drop of a single light-emitting diode is U4, and ΔU is the correction coefficient. The position and number of short-circuited light-emitting diodes can be determined according to the voltage value of the test terminal PA.

[0078] The following takes the digital tube time display device including the above-mentioned self-diagnosis circuit as an example to analyze in detail the working principle and process of the self-diagnosis repair method.

[0079] In the digital tube time display device, each of the 6-digit digital tubes consists of 7 segments arranged in the shape of a sun, which are used to display hours, minutes, and seconds respectively. The 2-digit digital tubes are used to display the colon between hours and minutes, and the colon between minutes and seconds. Each segment of each bit of hours, minutes, and seconds, the hours and minutes, and the two colons between minutes and seconds are composed of two LEDs connected in series, which are divided into a main segment LED string and a backup segment LED string. The short circuit and open circuit conditions of each main segment LED string are detected in the same way.

[0080] The LED connection method of each segment code of the time display module is as follows Figure 3 As shown, each LED has three conditions: normal, open circuit and short circuit. Two LEDs are connected in series, and the fault conditions that can be listed are shown in Table 2. From the analysis of the table, it can be obtained that in theory, short circuit and open circuit of LED can cause three conditions: infinite impedance, 0 impedance and 1 / 2 impedance. Each condition will cause the change of the detection voltage of the PA end of the MCU control system. Through the analysis of the working parameters of electronic components and multiple experiments, the threshold of the detection voltage of the PA port can be determined when each condition occurs, and the state of each segment code can be diagnosed based on the judgment of the threshold. The algorithm process is as follows:

[0081] Figure 3 The value of the power supply VCC is 5V, the saturation voltage drop of the two silicon transistors is about 0.3V, the forward voltage drop of the LED used in the present invention is about 1.8V, and the value of VCC' is 3.3V. Theoretically, the voltage value measured at the PA end should be about 0.8V under normal conditions. When any of the LEDs is open-circuited, the voltage value measured at the PA port should be 0V; when any of the LEDs is short-circuited, the voltage value measured at the PA port should be:

[0082] U1-U2-U3-(mn)U4+ΔU=5-0.3-0.3-1.8=2.6V;

[0083] When two LEDs are short-circuited at the same time, the voltage value measured at the PA port should be:

[0084] U1-U2-U3-(mn)U4+ΔU=5-0.3-0.3=4.4V;

[0085] At this time, the connected switch diode is turned on, playing a clamping protection role, and the voltage value measured at the test terminal PA is 3.3.

[0086] After multiple tests, when any of the two LEDs is disconnected, the voltage sampled by the ADC is less than 0.3V, when any of them is short-circuited, the voltage sampled by the ADC is 2.6V, and when both are short-circuited, the voltage sampled by the ADC is greater than 3.2V, which is basically the same as the theoretically derived value. Therefore, the voltage sampled by the ADC can be set between 0.05V and 0.5V as the voltage threshold range for disconnection. When the voltage sampled by the ADC is greater than 2V (correction coefficient is -0.6V), it is determined that the main segment LED is short-circuited, and then the standby segment LED is immediately activated.

[0087] Table 2 Classification of main segment LED string failures

[0088]

[0089] The voltage threshold range will be different for different power supply voltages and different transistor saturation voltage drops and LED forward voltage drops. Technicians in this field can calculate and modify the voltage threshold range according to specific applications, which are all within the protection scope of the present invention.

[0090] like Figure 4 As shown, in the embodiment of the digital tube time display device, the digital tube self-diagnosis and repair method includes the following steps:

[0091] Step S1 initializes the circuit power-on;

[0092] Step S2: Determine whether the fault flag is 0, if yes, proceed to S4, if no, proceed to step S3;

[0093] Step S3: the faulty segment code switches to the standby segment LED string to work;

[0094] Step S4: display the tens digit;

[0095] Step S5: ADC samples the voltage value of each segment code of the next digital tube to test whether it exceeds the threshold;

[0096] Step S6: when the fault segment code exceeds the limit, the fault segment code switches to the standby segment LED display, and the alarm information is uploaded to display the fault segment code and fault type;

[0097] Step S7: the ones digit when displaying;

[0098] Step S8: repeat S5, and sequentially perform detection and operation of the hour and minute colons, the tens digit of minutes, the units digit of minutes, the colon between minutes and seconds, the tens digit of seconds, and the units digit of seconds digital tubes.

[0099] It should be noted that the above specific implementations are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art should understand that various modifications, equivalent substitutions, changes, etc. can be made to the present invention. However, as long as these changes do not deviate from the spirit of the present invention, they should be within the scope of protection of the present invention. In addition, some terms used in the specification and claims of this application are not restrictive, but are only for the convenience of description.

Claims

1. A digital tube self-diagnosis and repair system, characterized in that: include: A power module, used for supplying power to the self-diagnosis and repair system; A self-diagnosis module, the self-diagnosis module includes a main position control decoder, a standby position control decoder, a main segment control shift register, a standby segment control shift register, and an N-bit digital tube, N is an integer greater than or equal to 1, wherein: the digital tube is composed of 7 segment codes, each of the segment codes is composed of two segments of LED strings, the main segment LED string is used for normal display, and the standby segment LED string is used for standby display, the output ends of the main position control decoder and the main segment control shift register are electrically connected to the main segment LED string, and the output ends of the standby position control decoder and the standby segment control shift register are electrically connected to the standby segment LED string; MCU control module, the MCU control module first uses the main segment control shift register and the standby segment control shift register to perform segment selection, and then uses the main position control decoder and the standby position control decoder to realize position selection. After the MCU control module detects that the voltage at the test end of the main segment LED string exceeds the threshold range, it automatically switches to the standby segment LED string to work; The main position control decoder is SM74HC138, the standby position control decoder is SM74HC138, the main segment control shift register is 74HC595D, and the standby segment control shift register is 74HC595D; The digital tube adopts a common anode connection mode; each output end of the main segment control shift register is respectively connected to the base of the corresponding main segment triode, the collector of the main segment triode is connected to the negative electrode of the main segment LED string, the emitter of the main segment triode is connected to the first end of the main segment resistor, the second end of the main segment resistor is grounded, and the emitter of the main segment triode leads to the test end PA and is connected to the AD sampling end of the MCU control module; Each output end of the standby segment control shift register is respectively connected to the base of the corresponding standby segment triode, the collector of the standby segment triode is connected to the cathode of the standby segment LED string, the emitter of the standby segment triode is connected to the first end of the standby segment resistor, and the second end of the standby segment resistor is grounded; Each output terminal of the master control decoder is connected to the base of the corresponding master transistor, the collector of the master transistor is connected to the positive electrode of the 7 main segment LED strings, and the emitter of the master transistor is connected to the power supply VCC; Each output end of the standby control decoder is connected to the base of the corresponding standby transistor, the collector of the standby transistor is connected to the positive electrodes of the 7 standby LED strings, and the emitter of the standby transistor is connected to the power supply VCC.

2. The digital tube self-diagnosis and repair system according to claim 1, characterized in that: Each output end of the main segment control shift register is respectively connected to one end of the corresponding base resistor R3, the other end of the base resistor R3 is connected to the base of the main segment transistor, the emitter of the main segment transistor is connected to the resistor R4 and the main segment resistor R5, the other end of the main segment resistor R5 is grounded, and the other end of the resistor R4 leads to the test terminal PA, the test terminal PA is electrically connected to the power supply VCC′ through the switching diode, and is grounded through the capacitor C1.

3. A digital tube self-diagnosis and repair method based on the digital tube self-diagnosis and repair system according to any one of claims 1 to 2, characterized in that: include: S1, initialize the circuit power-on; S2, determine whether the first digital tube fault flag is zero, if yes, go to S4, if no, go to S3; S3, the fault segment code switches to the standby segment LED string to work; S4, displaying the characters preset by the digital tube; S5, detect whether the voltage value of the test terminal PA of each segment of the next digital tube exceeds the threshold; S6. Determine whether there is a fault, fault segment code, and fault type through the voltage threshold range; S7. If there is no fault, proceed to step S4; if there is a fault, proceed to step S3.

4. The digital tube self-diagnosis and repair method according to claim 3, characterized in that: When a fault is detected in a main segment LED string of a certain segment code of the digital tube, an alarm message is uploaded to display the fault segment code and fault type.

5. The self-diagnosis and repair method of digital tube according to claim 3, characterized in that: The voltage threshold range includes an open circuit voltage threshold range and a short circuit voltage threshold range.

6. The self-diagnosis and repair method of digital tube according to claim 5, characterized in that: The circuit breaker voltage threshold range is that the voltage value of the segment code test terminal PA is between 0.05V and 0.5V.

7. The self-diagnosis and repair method of a digital tube according to claim 5, characterized in that: The short-circuit voltage threshold range is that the voltage value of the test end PA is greater than U1-U2-U3-(mn)U4+ΔU, where: the value of the power supply VCC is U1, the saturation voltage drop of the main stage transistor is U2, the saturation voltage drop of the main position transistor is U3, the main stage LED string is composed of m light-emitting diodes connected in series, n is the number of light-emitting diodes that are short-circuited, m and n are integers greater than 1, and n is less than or equal to m, the voltage drop of a single light-emitting diode is U4, and ΔU is the correction coefficient.

8. A digital tube time display device, characterized in that: It comprises the digital tube self-diagnosis and repair system as described in any one of claims 1 to 2.

9. The digital tube time display device according to claim 8, characterized in that: The number of the N-bit digital tubes is 8, and the 7 segments are arranged in a day shape to display hours, minutes, a colon between hours and minutes, seconds, and a colon between minutes and seconds.

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