Detection method and detection device for use current of LED lamp bead

Abstract

The invention discloses a detection method and a detection device for use current of an LED lamp bead, belongs to the field of LED lamp bead production devices, is used for an LED, and comprises a switch K1 and a switch K2, the circuit comprises a power supply controller, an ammeter, a digital display, a voltmeter, a transformer T1, a rectifier bridge D, a filter capacitor C1, a filter capacitor C2, a constant voltage module U1, a digital signal conversion module U2, a timing control module U3, a formula operation module U4, a storage operation module U5, relays J1 to J30, a relay J40, triodes Q1 to Q30, a resistor module and a resistor RS. According to the invention, the current and voltage borne by the LED lamp bead in the production process can be measured, and product design defects and product damage caused by inaccurate current and voltage parameters are avoided.

Description

Technical Field

[0001] The present application belongs to the field of LED lamp bead production devices, and more specifically, it relates to a method and device for detecting the current used by LED lamp beads. Background Art

[0002] In the production process of LED light sources (lamps), it is necessary to test the LED lamp beads before production to determine the current and voltage that the LED lamp beads can withstand, so as to design the LED light source product. However, in the prior art, the design of LED light sources mostly adopts the parameters provided by the LED lamp bead supplier, and these parameters are mostly calculated and provided in accordance with 1W / 3.3V=330mA. However, there is a large range of uncertainty in the parameters calculated and provided in accordance with 1W / 3.3V=330mA, resulting in uncertainty in the current that the LED lamp beads can withstand during use, and it is impossible to effectively guarantee the stability and reliability of the product during use. If design problems occur due to the above parameters during the design stage, it will cause immeasurable losses to the manufacturer of LED light sources.

[0003] Therefore, how to measure the current that the selected LED lamp beads can withstand during the design process of LED light sources has become a key technical problem that the industry needs to solve. Summary of the invention

[0004] The purpose of this application is to provide a method and device for detecting the current used by LED lamp beads, which can realize the measurement of the current and voltage borne by the LED lamp beads during the production process, thereby avoiding product design defects caused by inaccurate current and voltage parameters, resulting in product damage.

[0005] To achieve the above objectives, this application is implemented through the following technical solutions: A method for detecting the current used by an LED lamp bead described in the present application includes the following contents: using a power controller to calculate the theoretical current base value output by the power controller through a combination of a resistor RS set internally therein and different resistors in a resistor module through a formula operation module U4; obtaining the actual current value under the combination of a resistor RS set internally therein and different resistors in the resistor module through a digital signal conversion module U2 and a formula operation module U4, obtaining the difference between the theoretical current base value and the actual current value through a storage operation module U5, and the actual current value corresponding to the smallest difference is the maximum current value used by the LED lamp bead.

[0006] As one of the preferred technical solutions of the present application, the resistor RS in the power controller and the different resistors in the resistor module are connected in parallel.

[0007] A detection device for the above-mentioned detection method of the current used by the LED lamp beads, comprising a switch K1, a switch K2, and also comprising a power controller, an ammeter, a digital display, a voltmeter, a transformer T1, a rectifier bridge D, a filter capacitor C1, a filter capacitor C2, a constant voltage module U1, a digital signal conversion module U2, a timing control module U3, a formula operation module U4, a storage operation module U5, relays J1 to J30, relays J40, transistors Q1 to Q30, a resistor module, and a resistor RS, wherein the switch K1 is used to realize the on-off of the input of the power controller and the input of the transformer T1, the output of the power controller is electrically connected to the input of the ammeter, the ammeter is connected in series with the LED light bead to be tested, the voltmeter is connected in parallel with the LED light bead to be tested, the output of the transformer T1 is sent to the input of the filter capacitor C1 through the rectifier bridge D, the output of the filter capacitor C1 is electrically connected to the input of the constant voltage module U1, and the output VDD voltage of the constant voltage module U1 is electrically connected to the input of the filter capacitor C2; The output of the ammeter is electrically connected to the input of the switch K2, and the switch K2 is used to realize the input on-off of the relay J40. The output of the relay J40 is electrically connected to the input end of the digital signal conversion module U2, and the output end of the digital signal conversion module U2 is electrically connected to the input end of the timing control module U3. The output end of the timing control module U3 is electrically connected to the input end of the resistor RB1 to the resistor RB30 in the resistance module respectively, and the output end of the resistor RB1 to the resistor RB30 is electrically connected to the input end of the transistor Q1 to the transistor Q30 respectively. The output end of the transistor Q1 to the transistor Q30 is electrically connected to the + end of the relay J1 to the relay J30 respectively, and the input end of the relay J1 to the relay J30 is connected in parallel with the resistor RS, and the output end of the relay J1 to the relay J30 is electrically connected to the corresponding upper node end of the resistor RB1 to the resistor RB2; The output end of the digital signal conversion module U2 is electrically connected to the formula operation module U4. The formula operation module U4 obtains the theoretical value ΔIO and the measured value through the output end and is electrically connected to the input end of the storage operation module U5. The output of the storage operation module U5 is electrically connected to the input of the digital display and displays the critical current through the digital display.

[0008] As one of the preferred technical solutions of the present application, the power supply controller includes an input rectifier and filter circuit, an IC integrated controller, a signal shaping circuit, a current limiting circuit, a MOS tube, an oscillation transformer, an output rectifier and filter circuit, and an output end, which are electrically connected in sequence between the AC input circuit and the output end.

[0009] Compared with the prior art, the beneficial effects of this application are: The present application can use a detection device to calculate multiple groups of ideal theoretical current base values ​​and multiple groups of actually measured current values ​​under different resistance combinations, and subtract the theoretical current base value from the measured current value to obtain different differences. The smallest difference (including the negative minimum value) is the maximum current value of the LED lamp bead. The above method uses the detection device to use the current base value as the reference value, and the voltage value as the subordinate value, which can avoid the influence of the LED lamp bead current caused by factors such as working voltage, process materials, and temperature, and can also avoid the uncertainty caused by the parameter values ​​provided by the supplier, and avoid the product stability reduction or design defects caused by inaccurate current borne by the LED lamp bead. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is the circuit schematic diagram of this application.

[0011] Figure 2 is the schematic diagram of the power controller in this application.

[0012] Figure 3 The analysis of Table 1 Figure 1 .

[0013] Figure 4 The analysis of Table 1 Figure 2 .

[0014] Figure 5 The analysis of Table 2 Figure 1 .

[0015] Figure 6 The analysis of Table 2 Figure 2 .

[0016] Figure 7 The analysis of Table 3 Figure 1 .

[0017] Figure 8 The analysis of Table 3 Figure 2 .

[0018] In the figure: 1. AC input circuit; 2. Input rectification and filtering circuit; 3. IC integrated controller; 4. Signal shaping circuit; 5. Current limiting circuit; 6. MOS tube; 7. Oscillation transformer; 8. Output rectification and filtering circuit; 9. Output end. DETAILED DESCRIPTION

[0019] The technical solution described in this application is further described below in conjunction with the accompanying drawings and embodiments. Example

[0020] A method for detecting the current used by an LED lamp bead, the detection method comprising the following contents: using a power supply controller to calculate the theoretical current base value output by the power supply controller through a combination of a resistor RS set inside the power supply controller and different resistors in a resistor module through a formula operation module U4; obtaining the actual current value under the combination of the resistor RS set inside the power supply controller and different resistors in the resistor module through a digital signal conversion module U2 and a formula operation module U4, obtaining the difference between the theoretical current base value and the actual current value through a storage operation module U5, and the actual current value corresponding to the minimum difference (negative value is regarded as the minimum) is the maximum current value used by the LED lamp bead. Example

[0021] A detection device for the current used by an LED lamp bead comprises a switch K1, a switch K2, a power controller, an ammeter, a digital display, a voltmeter, a transformer T1, a rectifier bridge D, a filter capacitor C1, a filter capacitor C2, a constant voltage module U1, a relay J1, a relay J30, a relay J40, a digital signal conversion module U2, a timing control module U3, a transistor Q1, a transistor Q30, a transistor Q40, a resistance module, a resistor RS, a formula operation module U4, and a storage operation module U5.

[0022] The input of the switch K1 is connected to a 220V AC power supply, the output of the switch K1 is connected to the input of a power controller, the output of the power controller is connected to the input of an ammeter, the output of the ammeter is connected to the input of the LED lamp bead under test, and the voltmeter is connected in parallel with the LED lamp bead under test.

[0023] The output of the switch K1 is also electrically connected to the input of the transformer T1, the output of the transformer T1 is electrically connected to the input of the rectifier bridge D, the output of the rectifier bridge D is electrically connected to the input of the filter capacitor C1, the output of the filter capacitor C1 is electrically connected to the input of the constant voltage module U1, the output of the constant voltage module U1 is electrically connected to the input of the filter capacitor C2, and the output end of the constant voltage module U1 outputs the VDD voltage.

[0024] The output of the ammeter is also electrically connected to a switch K2, the output of the switch K2 is electrically connected to the input of the relay J40, and the output of the relay J40 is connected to the 1 end of the digital signal conversion module U2; the 6 ends of the digital signal conversion module U2 are connected to the input of the timing control module U3, and the 1 end to the 30 end of the timing control module U3 are respectively connected to the inputs of the resistors RB1 to RB30 in the resistance module, and the outputs of the resistors RB1 to RB30 are respectively electrically connected to the input ends of the transistors Q1 to Q30, and the output ends of the transistors Q1 to Q30 are respectively electrically connected to the + ends of the coils J1 to J30, and the input ends of the coils J1 to J30 are all connected in parallel with the resistor RS, and the outputs of the coils J1 to J30 are respectively electrically connected to the corresponding upper node ends of the resistors R1 to R30.

[0025] The output of the digital signal conversion module U2 is connected to the input 1 end of the formula operation module U4, the output 5 end of the formula operation module U4 is connected to the input 1 end of the storage operation module U5, the output 5 end of the storage operation module U5 is connected to the input end of the digital display, and the digital display is used to output the value of the critical current. Example

[0026] A detection device for the current used by an LED lamp bead, wherein the power supply controller comprises an AC input circuit 1 with an anti-surge function, an input rectifier and filter circuit 2, an IC integrated controller 3, a signal shaping circuit 4, a current limiting circuit 5, a MOS tube 6, an oscillation transformer 7, an output rectifier and filter circuit 8, and an output terminal 9, which are electrically connected in sequence.

[0027] The structure and connection relationship of the remaining parts are the same as the structure and connection relationship described in any of the above embodiments, and will not be repeated here to avoid cumbersome writing.

[0028] Based on the above embodiments, the following paragraphs will continue to describe in detail the technical features involved and the functions and roles played by the technical features in the present technical solution, so as to help technicians in this field to fully understand the technical solution and reproduce it.

[0029] In the present application, due to the influence of factors such as working voltage, process materials, temperature, etc., the working current of the LED lamp bead under test is nonlinear, wherein the change of working voltage can make the current change according to a certain exponent. The purpose of the present application is to provide a set of current base values ​​for LED lamp bead testing through a power supply controller, and use the voltage value as a subordinate value of the current base value. In the present application, the acquisition of the measured current value is achieved through the cooperation of the power supply controller, the ammeter, the digital signal conversion, the formula operation module, and the storage operation module, and the ammeter is used to realize the subjective observation of the measured current value. Since the measured current value in the above-mentioned detection device changes according to the exponential, it has a certain numerical difference with the theoretical current base value. The difference can be obtained by comparing the theoretical current base value with the measured current value. The difference shows a trend of change from large to small when the difference gradually increases from the minimum test current. When the test current gradually increases to a certain value, the difference between the theoretical current base value and the measured current value is the smallest (negative value is regarded as the smallest), which indicates that the chip current of the LED lamp bead under test is saturated at this time.

[0030] In this application, the line between the theoretical current base value points conforms to the linear growth trend of a linear function, while the measured current value grows exponentially. After many experiments, it can be found that the minimum difference between the theoretical current base value and the measured current value (including the minimum negative value when the difference is negative) is the maximum usage value used by the LED lamp bead under test. If the current continues to increase, causing the difference to increase from the minimum, the continued increase in current will have an uncertain value, and the current control will be lost, causing damage to the LED lamp bead.

[0031] During the experiment, the room temperature is controlled at about 20℃ to 30℃, the LED lamp beads are to be soldered on the aluminum substrate, in principle, the LED lamp beads to be tested are about 1W, and the LED lamp beads to be tested can be connected in series to about 30V.

[0032] In the present application, the switch K1 is connected to the input 220V AC power supply and sent to the transformer T1, a 10V voltage is output through the transformer T1, and connected to the filter capacitor C1 after passing through the rectifier bridge D. The filter capacitor C1 is 22μF50V. The filter capacitor C1 is connected to the input of the constant voltage module U1, and the constant voltage module U1 is 78L05D.

[0033] The output end of the constant voltage module U1 is connected to the input end of the filter capacitor C2. The filter capacitor C2 is 22μF50V. The filter capacitor also outputs a VDD voltage of 5V. The 5V VDD voltage output by the filter capacitor C2 is respectively supplied to the ammeter, voltmeter, digital display, digital signal conversion module U2, timing control module U3, formula operation module U4, storage operation module U5, relay J40, the + end of coil J1 and coil J30, transistor Q1 and the collector of transistor Q30 as VDD working voltage.

[0034] In the present application, the power controller + output terminal is connected to the input terminal of the ammeter, the output terminal of the ammeter is connected to the LED light source under test and displays the current value while lighting the LED light source. The voltmeter connected in parallel with the LED light source under test displays the voltage value of the LED light source under test.

[0035] In this application, the calculation of the core parameters of the power supply controller is extremely important. After determining the known data, accurate design and calculation must be carried out. The calculation contents include operating frequency, transformation ratio, duty cycle, on-time, transformer inductance, primary and secondary turns, magnetic induction intensity, maximum peak current, etc.

[0036] The maximum current required in this application is 0.4A, the output voltage is 33V, the maximum duty cycle D=0.43, and the transformer operating frequency is 65KHz, then the transformation ratio N=(V min )*D / (V0)*(1-D)=140*0.43 / 33*0.57=3.2; Maximum peak current I pk =(I0 / N*D)*2=(0.4 / 3.2*0.43)*2=0.58, take I pk =0.6.

[0037] Inductance Lp=Vmin*D / Ipk*F=140*0.43 / 0.6*65=1.544 Take 1.5mH Primary turns Np = 87 turns The magnetic induction intensity Bm is about 0.2. It can be seen that the transformer inductance can be selected as 1.5mH, and the primary and secondary turns can be selected as 87:27:14, which can meet the needs of the detection device.

[0038] The constant current control threshold of the IC integrated control in this application is 0.2V, and the constant current I0=0.5*3.2*0.2 / R. Then, it can be calculated that I0=320 / R(0.32=320mV) (Formula 1), where R is the parallel resistance obtained by connecting the resistor RS and the different resistors RB1 to RBN in the resistor module in parallel, where RBN is RB1 to RB30. For example, in this application, the resistor module includes RB1 to RB30. Resistance R=(RS*RBN) / (RS+RBN). (Formula 2) After stabilization for 5 minutes, press switch K2 to start the test.

[0039] In the present application, the coil + end of the relay J40 is used to input the VDD working voltage, the - end of the relay J40 is connected to the collector of the transistor Q40, the emitter of the transistor Q40 is grounded, and the base of the transistor Q40 is connected to the 6th terminal of the storage operation module U5 via the resistor R40. The 6th terminal of the storage operation module U5 is at a high level by default and can make the relay J40 closed and connected, and the current signal is transmitted to the input 1 terminal of the digital signal conversion module U2.

[0040] The input 1 end of the digital signal conversion module U2 receives the current numerical signal from J40 and causes its output 6 end to output a high level. The high level output by the digital signal conversion module U2 causes the input 34 end of the timing control module U3 to obtain a high level, and outputs a high level through the 31 end of the timing control module U3.

[0041] In the first group, when the timing control module U3 turns off terminal 31 after counting for 8 seconds, terminal 31 turns into a low level to control terminal 3 in the storage operation module U5 to save data. When the timing control module U3 counts to 10 seconds, the output terminal 1 and output terminal 31 of the timing control module U3 are both high levels, and the normally open contacts of the resistor RB1, transistor Q1, and relay J1 connected to terminal 1 of the timing control module U3 are closed. After the normally open contact of relay J1 is closed, the resistor R1 and the resistor RS can be connected in parallel to obtain the R value. The R value is calculated according to formula 2. At the same time, the detection device will obtain a measured current value I1, which is subjectively displayed by the ammeter and converted into a digital signal by the digital signal conversion module U2 and then sent to pins 1 and 3 of U4. The signal of pin 1 is directly supplied to U5-1 through pin 5. At the same time, the signal obtained by pin 3 is calculated by formula 1 (I0=320 / R) to obtain the theoretical value IO, which is supplied to U5-2 through pin 6. The storage operation module U5 stores the above ΔIO corresponding to IO ， And the measured current value I1 corresponding to ΔI1. And calculate the theoretical value and the measured value ΔI2. ΔI2=ΔI1-ΔIO Storage Group 1 In the second group, when the timing control module U3 counts for another 8 seconds, the terminal 31 is turned off, and the terminal 31 is thus changed to a low level. When the timing control module U3 counts to 10 seconds, the terminal 1 is turned off and the terminals 2 and 31 are turned on at the same time, and the terminals 2 and 31 are turned on at a high level. The terminals 2 of the timing control module U3 close the normally open contact of the relay J2 through the resistor RB2 and the transistor Q2. After the relay J2 is closed, the resistor RB2 is connected in parallel with the resistor RS to obtain the parallel ΔR value (Formula 2). At the same time, the detection device will obtain a new measured current value ΔI1, which is subjectively displayed through the ammeter and converted into a digital signal by the digital signal conversion module U2 and then sent to the 1st and 3rd pins of U4. The signal of the 1st pin is directly supplied to U5-1 through the 5th pin. At the same time, the signal obtained by the 3rd pin is calculated by formula 1 (I0=320 / R) to obtain a new theoretical value ΔIO, which is supplied to U5-2 through the 6th pin. The storage and calculation module U5 stores the above new ΔIO and ΔI1, and calculates the new theoretical value and the new measured value ΔI2. New ΔI2 = ΔI1 - ΔIO Storage Group 2 The timing control module U3 repeats the above second group of steps to realize the calculation of the third group of data to the 30th group of data, but changes the resistors RB1 to RB30, transistors Q1 to Q30, and relays J1 to J30 corresponding to the output terminals 1 to 30 in the timing control module U3, so as to obtain the R value after the resistors RB1 to RB30 are respectively connected in parallel with the resistor RS, respectively obtain the theoretical current value and the measured current value corresponding to different R values, and calculate and store the difference between the theoretical current value and the measured current value. The difference corresponding to the different R values ​​stored in the storage operation module U5 is compared, and the measured current value corresponding to the minimum difference (including the minimum negative value) is selected, and displayed on the digital display.

[0042] Specifically, after receiving the current value signal at the input 1 end of the digital signal conversion module U2, the current value signal is converted into a digital signal and sent to the input 1 end and the input 3 end of the formula operation module U4 through the output 2 end.

[0043] When the input 1 of the formula operation module U4 receives the current digital signal from the digital signal conversion module U2, a current value digital signal ΔI1 is generated, and the current value digital signal ΔI1 is supplied to the input 1 of the storage operation module U5 via the output 5 of the formula operation module U4. At this time, the 3 end of the storage operation module 5 is at a high level.

[0044] The 3rd terminal of the formula operation module U4 is connected to the 1st terminal. The 3rd terminal of the formula operation module U4 receives the signal at the same time and the theoretical current value ΔI0 is calculated by formula 1. This value is supplied to the input 2nd terminal of the storage operation module U5 via the output 6th terminal of the formula operation module U4.

[0045] The storage operation module U5 obtains two current digital signals ΔI0 and ΔI1. The storage operation module U5 subtracts the value of ΔI0 from the value of ΔI1 to obtain the value of current ΔI2. Terminal 3 of the storage operation module U5 waits until the timing control module U3 runs for 8 seconds and then turns off terminal 31. Terminal 31 of the timing control module U3 outputs a low level. At this time, terminal 3 of the storage operation module U5 is at a low level, and the storage operation module U5 saves the value ΔI1 and the value of the current difference ΔI2.

[0046] The operation of the first group of data includes: the timing control module U3 starts to run, the 31 terminal and the 1 terminal of the timing control module U3 are both changed to high level, the relay J1 is powered on and closed through the resistor RB1 and the transistor Q, the resistor RB1 is connected in parallel with the resistor RS to obtain the R value, and the current value of the ammeter A1 is changed by the obtained R value, and the current value signal is transmitted to the input 1 terminal of the digital signal conversion module U2. After the input 1 terminal of the digital signal conversion module U2 obtains the current value signal, it converts the current value signal into a digital signal and inputs it to the 2 terminal, and the input 1 terminal of the digital signal conversion module U2 converts the current value into a digital signal and supplies it to the input 1 terminal and the input 3 terminal of the formula operation module U4 through the output 2 terminal.

[0047] Terminal 1 of the formula operation module U4 receives the current signal from the digital signal conversion module U2 to generate a current value digital signal I1, which is given to terminal 1 of the storage operation module U5 through terminal 5 of the output of the formula operation module U4. At this time, terminal 3 of the storage operation module U5 is at a high level.

[0048] Terminal 3 of the formula operation module U4 is connected to terminal 1, and terminal 3 of the formula operation module U4 immediately performs formula calculation, and the formula calculation is performed according to formula 1 to obtain ΔI0, which is supplied to input terminal 2 of the storage operation module U5 via output terminal 6 of the formula operation module U4.

[0049] The storage and operation module U5 obtains two current digital signals ΔI1 and ΔI0, and operates on the two current digital signals to obtain the corresponding current difference ΔI2. Terminal 3 of the storage and operation module U5 waits until the timing control module U3 runs for 8 seconds and turns off terminal 31, and terminal 31 is at a low level. At this time, terminal 3 of the storage and operation module U5 is at a low level, and ΔI1 and ΔI2 are saved. The timing control module U3 runs for 10 seconds, turns off terminal 1, turns on terminals 2 and 31 to complete the first group of operations, and then runs and calculates the next group, and so on to obtain the 30 groups of values ​​claimed in the above paragraph.

[0050] The storage operation module U5 obtains the corresponding current difference ΔI2 by subtracting the two current digital signals ΔI1 and ΔI0 stored in each group. When the difference gradually decreases from the 0th group and becomes the minimum value (including the negative difference maximum absolute value which is the minimum value) and increases in the next group, the current has reached the critical point. The storage operation module U5 supplies the ΔI1 corresponding to the ΔI2 value of the previous group minimum group to the digital display through the output 5 terminal of the storage operation module U5 to display this current value. This current value is the maximum value of the current used. At this time, the storage operation module U5 reaches the critical point and delays for 3 seconds to make the 6th terminal of U5 become a low level, then Q40 is closed, and J40 loses power and disconnects the input detection to stop.

[0051] In this application, based on the contents described in the above paragraphs, test data of three types of LED lamp beads are provided in this embodiment. Table 1 is a test table of W60-3.2V-4B10C lamp beads. Table 2 is a test table of 1734-3.2V-1B12C lamp beads. Table 3 is a test table of 1128-6V-3B5C lamp beads.

[0052] Table 1W60-3.2V-4B10C lamp bead test table (RS3.97Ω)

[0053] Table 2 1734-3.2V-1B12C lamp bead test table (RS3.97Ω)

[0054] Table 3 Test table of 1128-6V-3B5C lamp beads (RS3.97Ω)

[0055] Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, all of which do not depart from the purpose of the present invention and should fall within the scope of protection of the claims of the present invention.

Claims

1. A method for detecting the current used by LED lamp beads, characterized in that: The detection method includes the following: The power controller is used to calculate the theoretical current base value output by the power controller through the combination of the resistor RS set inside it and different resistors in the resistor module through the formula operation module U4; the actual current value under the combination of the resistor RS set inside the power controller and different resistors in the resistor module is obtained through the digital signal conversion module U2 and the formula operation module U4, and the difference between the theoretical current base value and the actual current value is obtained through the storage operation module U5, and the actual current value corresponding to the smallest difference is the maximum current value used by the LED lamp bead.

2. The method for detecting the current used by LED lamp beads according to claim 1, characterized in that: The resistor RS in the power controller is connected in parallel with different resistors in the resistor module.

3. A detection device for the method for detecting the current used by an LED lamp bead according to claim 1 or 2, comprising a switch K1 and a switch K2, characterized in that: It also includes a power controller, an ammeter, a digital display, a voltmeter, a transformer T1, a rectifier bridge D, a filter capacitor C1, a filter capacitor C2, a constant voltage module U1, a digital signal conversion module U2, a timing control module U3, a formula operation module U4, a storage operation module U5, relays J1 to J30, relays J40, transistors Q1 to Q30, a resistor module, and a resistor RS, wherein the switch K1 is used to realize the on-off of the input of the power controller and the input of the transformer T1, the output of the power controller is electrically connected to the input of the ammeter, the ammeter is connected in series with the LED light bead to be measured, the voltmeter is connected in parallel with the LED light bead to be measured, the output of the transformer T1 is sent to the input of the filter capacitor C1 through the rectifier bridge D, the output of the filter capacitor C1 is electrically connected to the input of the constant voltage module U1, and the output VDD voltage of the constant voltage module U1 is electrically connected to the input of the filter capacitor C2; The output of the ammeter is electrically connected to the input of the switch K2, and the switch K2 is used to realize the input on-off of the relay J40. The output of the relay J40 is electrically connected to the input end of the digital signal conversion module U2, and the output end of the digital signal conversion module U2 is electrically connected to the input end of the timing control module U3. The output end of the timing control module U3 is electrically connected to the input end of the resistor RB1 to the resistor RB30 in the resistance module respectively, and the output end of the resistor RB1 to the resistor RB30 is electrically connected to the input end of the transistor Q1 to the transistor Q30 respectively. The output end of the transistor Q1 to the transistor Q30 is electrically connected to the + end of the relay J1 to the relay J30 respectively, and the input end of the relay J1 to the relay J30 is connected in parallel with the resistor RS, and the output end of the relay J1 to the relay J30 is electrically connected to the corresponding upper node end of the resistor RB1 to the resistor RB2; The output end of the digital signal conversion module U2 is electrically connected to the formula operation module U4. The formula operation module U4 obtains the theoretical value ΔIO according to the formula I0=320 / R, and the measured value is electrically connected to the input end of the storage operation module U5 through the output end. The output of the storage operation module U5 is electrically connected to the input of the digital display and displays the critical current through the digital display.

4. The detection device according to claim 3, characterized in that: The power supply controller comprises an input rectifying and filtering circuit (2), an IC integrated controller (3), a signal shaping circuit (4), a current limiting circuit (5), a MOS tube (6), an oscillating transformer (7), an output rectifying and filtering circuit (8), and an output end, which are electrically connected in sequence between an AC input circuit (1) and an output end.

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