A continuous pulse output control module and LED measurement system

Abstract

The present application relates to a continuous pulse output control module and an LED measurement system, which belongs to the field of LED testing technology. The continuous pulse output control module includes a current module matrix and an MCU, wherein the current module matrix includes at least two constant current drive units arranged in parallel, and the constant current drive unit is connected to the MCU. The present application can output a complete waveform and an accurate detection current, thereby improving the accuracy of LED spectrum measurement.

Description

Technical Field

[0001] The present application relates to the technical field of LED testing, and in particular to a continuous pulse output control module and an LED measurement system. Background Art

[0002] LED (Light Emitting Diode) is a solid-state lighting device driven by current. In what state can LED work efficiently, it is necessary to conduct quantitative analysis of the light / color / heat of LED devices. For this purpose, corresponding standards have been formulated internationally, and three quantitative analysis modes are given in the standards. The advantages and disadvantages of the three quantitative analysis modes are as follows:

[0003] DC measurement mode (DC Mode): The measured data is accurate, the LED generates a lot of heat, and the power range of the measured device is limited;

[0004] Single pulse measurement mode (Single Pules Mode): The measurement efficiency is high, but it cannot avoid the instantaneous accumulation of the junction temperature of the measured LED. The error between the measured data and the true value is large, and the measurement range is limited;

[0005] Continuous Pulse Measurement Mode: High measurement efficiency, avoiding temperature accumulation inside the LED being measured, measurement data close to that of DC measurement mode, and a wide power range for measuring devices.

[0006] By comparing their advantages and disadvantages, the continuous pulse measurement mode is more reasonable. It effectively avoids the error introduced by the heat generated in the measurement of high-power LEDs, expands the measurement power range, and greatly improves the use efficiency of the measurement device.

[0007] In the continuous pulse measurement mode, the pulse width of the continuous pulse must be less than or equal to 50uS (duty cycle is 1%), and the current waveform also has strict requirements. When measuring, the measured current is relatively large (such as the measured current is 10 amperes, or even more than tens of amperes), so the current drive device must output a relatively large instantaneous current and make the current waveform (di / dt) close to the ideal waveform, which is difficult for general current drive devices to achieve. Summary of the invention

[0008] In order to output a larger current and make the current waveform close to the ideal waveform, the present application provides a continuous pulse output control module and an LED measurement system.

[0009] In a first aspect, the present application provides a continuous pulse output control module, which adopts the following technical solution:

[0010] A continuous pulse output control module comprises a current module matrix and an MCU. The current module matrix comprises at least two constant current drive units arranged in parallel. The constant current drive units are connected to the MCU.

[0011] By adopting the above technical solution, the constant current drive units are set in parallel, and the current module matrix can output a larger current through the parallel superposition of current. Among them, the MCU controls the constant current drive unit to output the corresponding pulse current. The output current of a single constant current drive unit is small, which is convenient for outputting instantaneous current. The waveform of the current response is not easily distorted, so that the current size and waveform can meet the measurement standards. At the same time, the output current of a single constant current drive unit is small and the power is small, so that the heat generated by a single constant current drive unit is small, and there is no need to set up complex heat dissipation structures.

[0012] Optionally, it further includes control switches, the number of the control switches is the same as the number of the constant current drive units, and the control switches and the constant current drive units are connected in a one-to-one correspondence.

[0013] By adopting the above technical solution, the control switches and the constant current drive units correspond one to one. By closing different numbers of control switches, different numbers of constant current drive units can be controlled to output, and then the output current can be adjusted according to the needs of the sample being tested, thereby achieving segmented coarse adjustment of the output current.

[0014] Optionally, the control switch adopts a relay, and the relay is connected to the MCU.

[0015] By adopting the above technical solution, the relay has low cost and small impedance. The MCU controls the power on and off of the relay, and can automatically control the on and off of the branch where the corresponding constant current drive unit is located and switch the range.

[0016] Optionally, the MCU uses a chip model STM32F103.

[0017] By adopting the above technical solution, the chip model STM32F103 constitutes a time base control unit, which can accurately manage the generation of various waveforms.

[0018] Optionally, it also includes an integration circuit and a level clamping circuit, the integration circuit is connected to the level clamping circuit and the MCU respectively, and the level clamping circuit is connected to the constant current driving unit and the MCU respectively.

[0019] By adopting the above technical solution, the MCU has two pulse outputs, one is PWM1, the duty cycle of PWM1 is limited to 1% (pulse width is less than or equal to 50uS), and PWM1 is output to the output end of the level clamp circuit at the same time; the other is PWM2, PWM2 is output to the integration circuit, and after the integration circuit and the level clamp circuit, it becomes a low-impedance level and is clamped to PWM1, so that the amplitude of PWM1 changes, and the changed PWM1 is transmitted to the control end of the constant current drive unit, so that the constant current drive unit starts and its output current changes. The MCU increases or decreases the duty cycle of PWM2, and the amplitude of PWM2 remains unchanged. PWM2 forms a level value after integration of the integration circuit, and the level value increases or decreases accordingly with the change of the duty cycle, and then the level value is clamped on PWM1, and the amplitude of PWM1 increases or decreases accordingly, thereby increasing or decreasing the output current of the constant current drive unit, and realizing the fine adjustment of the output current. Through continuous feedback adjustment, the measurement accuracy is improved, so that the output current is equal to the target current value. Among them, the pulse width of PWM1 remains unchanged.

[0020] Optionally, the integration circuit includes a first resistor R1, a first capacitor C1 and a second resistor R2, one end of the first resistor R1 is connected to the MCU, the other end of the first resistor R1 is connected to the level clamping circuit and one end of the first capacitor C1, the other end of the first capacitor C1 is grounded, and the second resistor R2 and the first capacitor C1 are connected in parallel.

[0021] By adopting the above technical solution, an integration circuit is formed by the first resistor R1, the first capacitor C1 and the second resistor R2, which is simple and practical.

[0022] Optionally, the level clamping circuit includes an operational amplifier A, a third resistor R3, a transistor Q, a diode D and a fourth resistor R4, the in-phase end of the operational amplifier A is connected to the integration circuit, the inverting end of the operational amplifier A is connected to the output end of the operational amplifier A, the output end of the operational amplifier A is connected to one end of the third resistor R3, the other end of the third resistor R3 is connected to the base of the transistor Q, the collector of the transistor Q is connected to VCC, the emitter of the transistor Q is connected to the cathode of the diode D and one end of the fourth resistor R4, the anode of the diode D is respectively connected to the MCU and the constant current drive unit, and the other end of the fourth resistor R4 is grounded.

[0023] By adopting the above technical solution, the operational amplifier A forms a voltage follower, and PWM2 forms a low-resistance level after being processed by the integration circuit and the voltage follower. The clamping circuit is formed by the diode D, and the amplitude of PWM1 is clamped by the level to form a composite waveform with a constant pulse width and variable amplitude, and is transmitted to the DIM terminal of the constant current drive unit.

[0024] In a second aspect, the present application provides an LED measurement system, which adopts the following technical solution:

[0025] An LED measurement system comprises the above-mentioned continuous pulse output control module, a power supply and a spectrum detection device, wherein the constant current driving unit is connected to the power supply, and the spectrum detection device is connected to a sample to be measured.

[0026] By adopting the above technical solution, the power supply outputs electric energy to the constant current drive unit, and the MCU outputs a pulse signal to the constant current drive unit, so that the constant current drive unit outputs a pulse current. The constant current drive units are arranged in parallel, and through the superposition of currents, a larger pulse current can be output. The pulse current acts on the sample under test, and the sample under test emits light. The spectrum detection device measures the light emitted by the sample under test.

[0027] Optionally, it also includes a host computer and a measurement meter, wherein the measurement meter is connected to the current module matrix and the host computer respectively, and the host computer is connected to the MCU and the spectrum detection device respectively.

[0028] By adopting the above technical solution, the measuring meter detects the superimposed current and sends the detected data to the host computer, which compares the detected data with the target value and sends corresponding information to the MCU according to the comparison result, and the MCU adjusts the output of the constant current drive unit according to the comparison result. The host computer receives the detection data of the spectrum detection device.

[0029] Optionally, the measuring meter adopts an average value voltmeter.

[0030] By adopting the above technical solution, the average value voltmeter detects the current of multiple cycles, converts the pulse current of 50uS and 1% duty cycle on the tested sample into the voltage average value, and then sends it to the host computer in digital form, which can improve the detection accuracy.

[0031] In summary, the present application includes at least one of the following beneficial technical effects:

[0032] 1. The constant current drive units are set in parallel so that the current module matrix can output a larger current. Among them, the output current of a single constant current drive unit is small, which is convenient for outputting instantaneous current, and the waveform of the current response is not easily distorted, so that the current waveform can meet the measurement standard.

[0033] 2. The control switch and the constant current drive unit correspond one to one. The MCU controls the closing of the corresponding control switch to control different numbers of constant current drive units to output, and then the output current can be adjusted according to the needs of the sample under test. The output current can be roughly adjusted in sections to meet the requirements of various power measurements.

[0034] 3. By setting an integration circuit and a level clamping circuit, the amplitude of PWM1 is adjusted according to the level value converted by PWM2, and then the output current of the constant current drive unit is adjusted, and the current can be fine-tuned. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a structural block diagram of a continuous pulse output control module in one embodiment of the present application;

[0036] Figure 2 This is the circuit diagram of the ACT001 chip;

[0037] Figure 3 This is a structural block diagram of a continuous pulse output control module in another embodiment of the present application;

[0038] Figure 4 It is a connection diagram between the integration circuit, level clamping circuit, MCU, constant current drive unit and host computer;

[0039] Figure 5 is a structural block diagram of an LED measurement system in one embodiment of the present application;

[0040] Figure 6 is a structural block diagram of an LED measurement system in another embodiment of the present application;

[0041] Figure 7 It is a waveform diagram of current and PWM1.

[0042] Explanation of the reference numerals: 10, power supply; 20, current module matrix; 21, constant current driving unit; 30, sample under test; 41, integration circuit; 42, level clamping circuit; 43, host computer; 44, measuring meter; 50, control switch; 60, spectrum detection device. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solutions and advantages of this application more clear, the following Figure 1-7 It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0044] The present application embodiment discloses a continuous pulse output control module. Figure 1 The continuous pulse output control module includes a current module matrix 20 and an MCU. The current module matrix 20 includes at least two constant current drive units 21 arranged in parallel. The constant current drive units 21 are all connected to the MCU.

[0045] Multiple constant current drive units 21 are arranged in parallel, and the current module matrix 20 can output a larger current through the parallel superposition of current. The MCU controls the constant current drive unit 21 to output the corresponding pulse current. The output current of a single constant current drive unit 21 is small, which is convenient for outputting instantaneous current, and the waveform of the current response is not easily distorted.

[0046] refer to Figure 2 In this embodiment, the constant current drive unit 21 can use a chip of model ACT001 and its peripheral circuits. The ACT001 chip has the advantages of strong load capacity, switching frequency up to 1MHz, ideal constant current waveform, and multiple modules can work in parallel with a common anode (the common anode is that each unit can be directly connected to the positive electrode of the power supply 10). The constant current drive unit 21 can also use other types of chips, such as a chip of model LM3402, as long as it has a constant current output and can be dimmed according to PWM.

[0047] Optional, see Figure 3 The continuous pulse output control module also includes a control switch 50, an integration circuit 41 and a level clamping circuit 42.

[0048] The number of control switches 50 is the same as the number of constant current drive units 21, and the control switches 50 and the constant current drive units 21 are connected one by one. In this embodiment, the control switch 50 can be a relay, and the relay is connected to the MCU. The control switch 50 can also be other switches, such as an optical coupler; the control switch 50 can also be a manual switch.

[0049] The test sample 30 is connected to the output end of the current module matrix 20. For example, the output current of each constant current drive unit 21 is 200mA. If the detection current of the test sample 30 is 1A, the five constant current drive units 21 can output a superimposed current of 1A. At this time, the MCU controls the five control switches 50 to close, and the branches where the five corresponding constant current drive units 21 are located are turned on. The current module matrix 20 outputs a current of 1A to act on the test sample 30. By controlling different numbers of constant current drive units 21, the current can be roughly adjusted in sections.

[0050] Reference Figure 3 and Figure 4 The integration circuit 41 is connected to the level clamping circuit 42 and the MCU respectively. The integration circuit 41 includes a first resistor R1, a first capacitor C1 and a second resistor R2. One end of the first resistor R1 is connected to the MCU, the other end of the first resistor R1 is connected to the level clamping circuit 42 and one end of the first capacitor C1, the other end of the first capacitor C1 is grounded, and the second resistor R2 is connected to the first capacitor C1 in parallel.

[0051] The level clamp circuit 42 is connected to the constant current drive unit 21 and the MCU respectively, and the level clamp circuit 42 includes an operational amplifier A, a third resistor R3, a transistor Q, a diode D and a fourth resistor R4, wherein the transistor Q is an NPN transistor. The in-phase end of the operational amplifier A is connected to the first resistor R1, the first capacitor C1, and the second resistor R2, the inverting end of the operational amplifier A is connected to the output end of the operational amplifier A, the output end of the operational amplifier A is connected to one end of the third resistor R3, the other end of the third resistor R3 is connected to the base of the transistor Q, the collector of the transistor Q is connected to VCC, the port voltage of VCC is 5V, the emitter of the transistor Q is connected to the cathode of the diode D and one end of the fourth resistor R4, the anode of the diode D is connected to the MCU and the constant current drive unit 21 respectively, and the other end of the fourth resistor R4 is grounded.

[0052] The MCU uses a chip of model STM32F103. The MCU has two pulse outputs. The first pulse signal is PWM1 with a duty cycle of 1% (pulse width is less than or equal to 50uS). The output end of the first pulse signal is connected to the fifth resistor R5 and the second capacitor C2. One end of the fifth resistor R5 is connected to the MCU, and the other end of the fifth resistor R5 is connected to the anode of the diode D and the constant current drive unit 21. The second capacitor C2 is connected in parallel with the fifth resistor R5. The fifth resistor R5 and the second capacitor C2 play a role in improving the square wave shaping of PWM1. The second pulse signal is PWM2, and the output end of the second pulse signal is connected to the first resistor R1. MCU can change the duty cycle of PWM2. After PWM2 passes through the integration circuit 41 and the level clamping circuit 42, PWM2 is clamped by the level clamping circuit 42, so that the amplitude of PWM1 changes. The clamped PWM1 is transmitted to the DIM port of the constant current driving unit 21, so that the output current of the constant current driving unit 21 changes, and the output current is fine-tuned to make the current flowing through the sample 30 under test more accurate.

[0053] The present application also discloses an LED measurement system, referring to Figure 5 The LED measurement system includes the above-mentioned continuous pulse output control module, as well as a power supply 10 and a spectrum detection device 60, the constant current driving unit 21 is connected to the power supply 10, the spectrum detection device 60 is connected to the measured sample 30, and the spectrum detection device 60 includes a spectrometer and an integrating sphere.

[0054] The power supply 10 provides electrical energy to the constant current driving unit 21, and the MCU outputs a pulse signal to the constant current driving unit 21, so that the constant current driving unit 21 outputs a pulse current. The superimposed pulse current acts on the sample under test 30, and the sample under test 30 emits light. The spectrum detection device 60 measures and integrates the light emitted by the sample under test 30.

[0055] Optional, see Figure 6The LED measurement system further includes a host computer 43 and a measuring meter 44. The measuring meter 44 is respectively connected to the current module matrix 20, the host computer 43, and the sample 30 to be measured. The host computer 43 is respectively connected to the MCU and the spectrum detection device 60. In this embodiment, the host computer 43 is a computer, and the measuring meter 44 can be an average voltage meter. The measuring meter 44 can also be other measuring instruments, such as an ammeter.

[0056] Specifically, the average voltage meter converts the pulse current with a duty cycle of 1% (pulse width less than or equal to 50uS) into a voltage average value, and sends it to the host computer 43 in digital form through the communication serial port, and the host computer 43 calculates the corresponding multiplier of the voltage average value. In this embodiment, the host computer 43 amplifies the voltage average value by 100 times, and then compares the voltage average value with the target value. If the voltage average value is higher than the target value, the host computer 43 sends a corresponding signal to the MCU, and the MCU reduces the duty cycle of PWM2, integrates the PWM2 and clamps it on PWM1, and the amplitude of PWM1 is reduced accordingly, so that the output current of the constant current drive unit 21 is reduced; if the voltage average value is lower than the target value, the MCU increases the duty cycle of PWM2, integrates the PWM2 and clamps it on PWM1, and the amplitude of PWM1 is increased accordingly, so that the output current of the constant current drive unit 21 is increased. Through continuous feedback correction, the current flowing through the sample 30 under test is equal to the target current or within the allowable error.

[0057] The implementation principle of an LED measurement system in the embodiment of the present application is as follows: according to the measurement requirements of the sample 30 to be tested, the corresponding target current is inputted into the host computer 43, the host computer 43 sends the information of the target current to the MCU, the MCU controls the corresponding number of control switches 50 to close according to the target current, so that the corresponding number of constant current drive units 21 are started, and the output current of the constant current drive unit 21 is superimposed on the sample 30 to be tested. The measurement meter 44 sends the detected voltage average value to the host computer 43, the host computer 43 compares the voltage average value with the target value corresponding to the target current, and sends the corresponding information to the MCU according to the comparison result, the MCU increases or decreases the duty cycle of PWM2 according to the information, PWM2 is clamped on PWM1 after passing through the integration circuit 41 and the level clamp circuit 42, the amplitude of PWM1 increases or decreases accordingly, and then the output current of the constant current drive unit 21 increases or decreases. Through continuous feedback correction, the current flowing through the sample 30 to be tested is equal to the target current or within the allowable error.

[0058] refer to Figure 7 The data measured by the measuring table 44 is equal to the target value after being multiplied by the magnification. It can be considered that the area S formed by the current waveform is equal to the energy of the predetermined waveform. According to the spectrum integration method of the continuous pulse mode, the measured spectrum value is also accurate.

[0059] The above are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. Any feature disclosed in this specification (including the abstract and drawings), unless otherwise stated, can be replaced by other equivalent or alternative features with similar purposes. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

Claims

1. A continuous pulse output control module, Features: It comprises a current module matrix (20) and an MCU, wherein the current module matrix (20) comprises at least two constant current drive units (21) arranged in parallel, and the constant current drive unit (21) is connected to the MCU; It also includes an integration circuit (41) and a level clamping circuit (42), wherein the integration circuit (41) is connected to the level clamping circuit (42) and the MCU respectively, and the level clamping circuit (42) is connected to the constant current driving unit (21) and the MCU respectively; The integration circuit (41) comprises a first resistor R1, a first capacitor C1 and a second resistor R2, one end of the first resistor R1 is connected to the MCU, the other end of the first resistor R1 is connected to the level clamping circuit (42) and one end of the first capacitor C1, the other end of the first capacitor C1 is grounded, and the second resistor R2 and the first capacitor C1 are connected in parallel; The level clamping circuit (42) comprises an operational amplifier A, a third resistor R3, a transistor Q, a diode D and a fourth resistor R4; the in-phase end of the operational amplifier A is connected to the integration circuit (41); the inverting end of the operational amplifier A is connected to the output end of the operational amplifier A; the output end of the operational amplifier A is connected to one end of the third resistor R3; the other end of the third resistor R3 is connected to the base of the transistor Q; the collector of the transistor Q is connected to VCC; the emitter of the transistor Q is connected to the cathode of the diode D and one end of the fourth resistor R4; the anode of the diode D is respectively connected to the MCU and the constant current drive unit (21); and the other end of the fourth resistor R4 is grounded.

2. The continuous pulse output control module according to claim 1, Features: It also includes control switches (50), the number of the control switches (50) is the same as the number of the constant current drive units (21), and the control switches (50) and the constant current drive units (21) are connected in a one-to-one correspondence.

3. The continuous pulse output control module according to claim 2, Features: The control switch (50) is a relay, which is connected to the MCU.

4. The continuous pulse output control module according to claim 1, Features: The MCU adopts a chip of type STM32F103.

5. An LED measurement system, Features: It comprises a continuous pulse output control module as described in any one of claims 1 to 4, as well as a power supply (10) and a spectrum detection device (60), wherein the constant current drive unit (21) is connected to the power supply (10), and the spectrum detection device (60) is connected to the sample to be tested (30).

6. The LED measurement system according to claim 5, Features: It also includes a host computer (43) and a measurement meter (44), wherein the measurement meter (44) is connected to the current module matrix (20) and the host computer (43) respectively, and the host computer (43) is connected to the MCU and the spectrum detection device (60) respectively.

7. The LED measurement system according to claim 6, Features: The measuring meter (44) adopts an average value voltmeter.

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