Device for measuring leakage current of light emitting diode

Abstract

The utility model discloses a light emitting diode leakage current measuring device which comprises a power supply module, a transimpedance amplification module, an AD sampling module and a processing module. The power supply module provides reverse bias voltage for a light emitting diode and is electrically connected with an electrode of the light emitting diode through an analog switch. The transimpedance amplification module converts a current signal of the light emitting diode into a voltage signal, a transimpedance amplification circuit comprising a transimpedance amplifier is adopted, and the input end of the transimpedance amplification circuit is electrically connected with the common end of the light emitting diode; the AD sampling module is electrically connected with the output end of the transimpedance amplification module and is used for sampling the voltage signal converted by the light emitting diode into a digital signal; and the processing module processes the power supply circuit signal and exports light emitting diode leakage current data measured by the AD sampling module. The device is simple in structure, convenient and fast to operate, high in detection precision and stable in effect, and can be widely applied to batch leakage current detection work in RGB light emitting diode industrial production.

Description

Technical Field

[0001] The utility model relates to a light emitting diode leakage current measuring device, belonging to the diode detection circuit technology. Background Art

[0002] Existing methods for measuring leakage current of diodes include a reverse bias method and a high impedance current measurement method.

[0003] The reverse bias method is to reverse bias the diode and indirectly measure the leakage current by measuring its reverse current. This method is simple and easy to implement, but it is limited by low measurement accuracy, especially in the small current range. It may be affected by environmental conditions and instruments, resulting in low measurement accuracy, which is difficult to meet application scenarios with high requirements for leakage current accuracy.

[0004] The high impedance current measurement method uses a high impedance amplifier or a special leakage current measurement instrument to measure the leakage current of the diode. This method requires high-precision, high-performance leakage current measurement equipment, which is usually expensive. For some small and medium-sized enterprises or laboratories, the equipment cost is the main limiting factor. In addition, although the high impedance current measurement method has high accuracy, it requires a long measurement time in actual applications. It is only suitable for experimental operations and cannot meet the demand for fast measurement in production, affecting production efficiency.

[0005] Existing leakage current measurement technology is difficult to popularize in large-scale industrial production applications. Some measurement methods may work well in small-scale sample testing, but when applied on large-scale production lines, there are problems of insufficient accuracy and low efficiency, and they cannot meet the requirements of high efficiency and high precision. Utility Model Content

[0006] Aiming at the problems of poor detection accuracy and low detection efficiency in the existing leakage current measurement technology, the utility model studies a novel light emitting diode leakage current measurement device to achieve high-precision and high-speed detection of light emitting diode leakage current.

[0007] The utility model is implemented by the following technical solutions:

[0008] A light emitting diode leakage current measuring device, comprising:

[0009] A power supply module for providing a reverse bias voltage to the light emitting diode, wherein the power supply module is electrically connected to the electrode of the light emitting diode through an analog switch and applies a reverse voltage to the light emitting diode in a polling manner;

[0010] A transimpedance amplification module for converting a current signal of a light-emitting diode into a voltage signal, wherein the transimpedance amplification module adopts a transimpedance amplification circuit including a transimpedance amplifier, and an input end of the transimpedance amplification circuit is electrically connected to a common end of the light-emitting diode;

[0011] The AD sampling module is electrically connected to the output end of the transimpedance amplifier circuit and samples the voltage signal converted by the light-emitting diode into a digital signal;

[0012] The processing module is connected to the power supply module, the analog switch and the AD sampling module for communication, processes the power supply circuit signal and exports the light emitting diode leakage current data measured by the AD sampling module.

[0013] In a light-emitting diode leakage current measuring device of the utility model, further, the power supply module adopts a 16-bit adjustable reference voltage source, the adjustable voltage value is 0-2.5V, the reference voltage source output is connected to a voltage amplification module, and the voltage amplification module adopts a voltage amplification circuit to amplify and output the output voltage of the power supply module.

[0014] In a light-emitting diode leakage current measuring device of the utility model, further, the voltage amplification circuit adopts TP1252-SR as a high-voltage operational amplifier, and a transistor is arranged at the output end of the voltage amplification circuit, and the output voltage of the reference voltage source is amplified by operational amplification and transistor amplification.

[0015] In a light emitting diode leakage current measuring device of the utility model, further, the transimpedance amplifier circuit is provided with a feedback resistor connected in parallel with the transimpedance amplifier, and the ratio between the feedback resistor and the input resistance of the transimpedance amplifier is adjusted to adjust the amplification factor of the transimpedance amplifier.

[0016] In a light emitting diode leakage current measuring device of the utility model, preferably, the transimpedance amplifier uses OPA381AIDGKR and GS8552-SR connected in series.

[0017] In the light emitting diode leakage current measuring device of the utility model, preferably, the AD sampling module adopts a 24-bit AD sampler.

[0018] In the light emitting diode leakage current measuring device of the utility model, preferably, the processing module adopts a single chip microcomputer.

[0019] In a light-emitting diode leakage current measuring device of the utility model, further, the light-emitting diode is an RGB light-emitting diode, and the power supply module outputs two constant voltage circuits, wherein a 20V reference voltage is provided to the red lamp beads of the RGB light-emitting diode, and a 10V reference voltage is provided to the green and blue lamp beads of the RGB light-emitting diode.

[0020] The utility model adopts the above technical solution to measure the leakage current of the light emitting diode, which has the following beneficial effects:

[0021] (1) High sensitivity. The leakage current of a light-emitting diode is usually a very small current. The transimpedance amplifier module in the utility model uses a transimpedance amplifier to convert the weak current signal of the light-emitting diode into a corresponding voltage signal, thereby improving the sensitivity of detection.

[0022] (2) Low distortion. The transimpedance amplifier module in the utility model uses a transimpedance amplifier to convert the current signal of the light-emitting diode, which has the characteristics of low distortion and can accurately amplify the input signal without introducing additional distortion or distortion. This makes it possible to maintain the original characteristics of the signal when amplifying the leakage current signal of the light-emitting diode, and will not generate additional errors, thereby improving the accuracy of detection. The measurement accuracy of the reverse leakage current can reach 0.05μA.

[0023] (3) Wide bandwidth. The LED leakage current signal may be affected by environmental interference or circuit noise. The transimpedance amplifier module in the utility model uses a transimpedance amplifier with a wide bandwidth range, which can process higher frequency signals and effectively suppress these interferences, thereby improving the accuracy and stability of detection.

[0024] (4) Adjustability. The transimpedance amplifier used in the transimpedance amplifier module of the present invention can adjust the signal amplification factor by adjusting the resistance value, so that the amplified signal is suitable for the input range of the subsequent AD sampling module or data collector as needed, further improving the detection accuracy and flexibility.

[0025] (5) Low cost. The utility model uses a transimpedance amplifier to convert the current signal of the light-emitting diode, which is lower in cost than special leakage current measuring instruments such as high impedance amplifiers.

[0026] To sum up, the utility model aims to solve the problems of low detection accuracy, long detection time and unstable detection effect in the existing method for measuring the leakage current of light-emitting diodes. The leakage current of the three-color lamp beads is converted into a voltage signal by a transimpedance amplifier circuit, and high-precision AD sampling is used to achieve fast and accurate measurement of the leakage current. The test device of the utility model has a simple structure and is easy and fast to operate. It can be widely used in batch leakage current detection in the industrial production of RGB light-emitting diodes.

[0027] The utility model is further described below in conjunction with the accompanying drawings and specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The utility model is a schematic diagram of a module of a light emitting diode leakage current measuring device.

[0029] Figure 2 FIG. 4 is a schematic diagram of a power circuit of a power module in an embodiment.

[0030] Figure 3Schematic diagram of a voltage amplification circuit of a power module in an embodiment.

[0031] Figure 4 FIG. 4 is a circuit diagram of an analog switch in an embodiment.

[0032] Figure 5 Schematic diagram of a transimpedance amplifier circuit of a transimpedance amplifier module in an embodiment.

[0033] Figure 6 Schematic diagram of the sampling circuit of the AD sampling module in the embodiment.

[0034] Figure 7 Schematic diagram of the single chip microcomputer interface of the processing module in the embodiment.

[0035] Numbers in the figure: 100 - power supply module, 110 - voltage amplifier module, 120 - analog switch, 200 - light emitting diode, 300 - transimpedance amplifier module, 400 - AD sampling module, 500 - processing module. DETAILED DESCRIPTION

[0036] See also Figure 1 , the figure shows the structure of the light emitting diode leakage current measuring device of the utility model, including a power module 100, a light emitting diode 200, a transimpedance amplifier module 300, an AD sampling module 400 and a processing module 500, wherein the power module 100 provides a reverse bias voltage to the light emitting diode 200 to be detected, the power module 100 is electrically connected to the positive and negative electrodes of the light emitting diode 200 to be detected through an analog switch 120, the analog switch 120 controls the reverse application of voltage to the light emitting diode 200, the transimpedance amplifier module 300 converts the current signal of the light emitting diode into a voltage signal, the transimpedance amplifier module 300 adopts a transimpedance amplifier circuit including a transimpedance amplifier, and the input end of the transimpedance amplifier circuit is electrically connected to the common end of the light emitting diode 200 to be detected. The AD sampling module 400 is electrically connected to the output end of the transimpedance amplifier circuit in the transimpedance amplifier module 300, and converts the voltage signal of the light emitting diode to be detected output by the transimpedance amplifier module 300 into a digital signal. The processing module 500 is in communication connection with the AD sampling module 400 , and derives leakage current detection values ​​of the corresponding light emitting diodes in different time periods according to the voltage applied by the power supply module 100 to the light emitting diodes 200 to be detected.

[0037] This embodiment uses the above detection device to detect leakage current of a group of RGB light-emitting diodes, and connects the red, green and blue three-color lamp bead leakage current signal of the RGB light-emitting diode to the input end of the transimpedance amplifier. Utilizing the high gain and low distortion characteristics of the transimpedance amplifier, based on Ohm's law and the feedback principle of the amplifier, when the current flows through the input end of the transimpedance amplifier, a voltage signal proportional to the current will be generated, which will be amplified by the amplifier circuit inside the amplifier, and a corresponding amplified voltage signal will be output to amplify and convert the weak leakage current signal of the light-emitting diode into a voltage signal. Therefore, this embodiment connects the transimpedance amplifier to the common end of the leakage current of the light-emitting diode, converts the leakage current signal into a voltage signal and amplifies it, and measures and analyzes it through the subsequent AD sampling module 400. This detection method effectively improves the accuracy and stability of the light-emitting diode leakage current detection.

[0038] The following combination Figure 2-7 This embodiment is described in detail.

[0039] First, an adjustable reverse bias voltage is set for the RGB light-emitting diode to be detected, where the red lamp bead voltage of the RGB light-emitting diode is set to 20V, and the green and blue voltages are set to 10V, so a reference voltage of 20V and 10V is required. The three lamp beads of multiple RGB light-emitting diodes to be detected are respectively connected to the wiring terminals for access to the detection circuit.

[0040] See also Figure 2 and Figure 3 The power module 100 of this embodiment includes a 16-bit adjustable reference voltage source outputting an adjustable voltage value of 0 to 2.5V. Specifically, the reference voltage source AD5660CRMZ-1D is used, which is divided into two groups to output the reference voltage HU_R_IN corresponding to the red lamp bead of the RGB light-emitting diode and the reference voltage HU_GB_IN corresponding to the green and blue lamp bead. Figure 2 The power module 100 amplifies the output voltage of the reference voltage source through the voltage amplifier module 110. The voltage amplifier module 110 adopts Figure 3The voltage amplifier circuit shown uses a high-voltage operational amplifier of model TP1252-SR, and a triode is set at the output end of the voltage amplifier circuit. The output voltage of the reference voltage source is amplified by 10 times through the operational amplification and triode amplification of the high-voltage operational amplifier, and the entire power module 100 outputs the amplified voltage through the triode. In this embodiment, a triode of model MMBT4401-C2144 is respectively set on two groups of output circuits connected to the two pins OUTA and OUTB of TP1252-SR, and the output voltage of the power module is amplified by 10 times, generating a voltage value of 20V and a voltage value of 10V, and amplifying and outputting two voltages IRU_R_OUT and IRU_R_OUT according to the voltage values ​​required by different lamp beads of RGB light-emitting diodes, and then the amplified voltage is polled and reversely applied to the positive and negative ends of the three color lamp beads of the RGB light-emitting diode through the analog switch 120. The arrangement of electrical components in the voltage amplifier circuit is a known technology of the corresponding model voltage amplifier, and the product manual of TP1252-SR can be referred to for details.

[0041] Specific as Figure 4 As shown, the analog switch of this embodiment adopts ADG1434YRUZ-REEL7, its S4B pin is connected to the amplified output voltage IRU_R_OUT of the red lamp bead of the corresponding RGB light-emitting diode, S1B and S2B pins are connected to the amplified output voltage IRU_GB_OUT of the green and blue lamp beads of the corresponding RGB light-emitting diode, and its S3B pin is connected to the common end of the RGB light-emitting diode and connected to the input IR_I_IN of the transimpedance amplifier circuit.

[0042] In this embodiment, the common end of the RGB light-emitting diode is connected to the transimpedance amplifier module 300, and is electrically connected to the input end IR_I_IN of the transimpedance amplifier. After the I / V conversion of the transimpedance amplifier, the lamp bead current signal of the RGB light-emitting diode is converted into a voltage signal output. Figure 5 As shown, the transimpedance amplifier of this embodiment uses OPA381AIDGKR and GS8552-SR arranged in parallel, and uses an adjustable feedback resistor R100 in parallel with OPA381AIDGKR. The feedback resistor R100 can be adjusted by replacing a resistor with a different resistance value or using a variable resistor to adjust the resistance value, and adjusting the ratio of the feedback resistor and the input resistance of the transimpedance amplifier to achieve the adjustment of the amplification factor of the transimpedance amplifier. The arrangement of electrical components in the transimpedance amplifier circuit is a known technology for the corresponding model of the transimpedance amplifier, and specific reference can be made to the product manuals of OPA381AIDGKR and GS8552-SR.

[0043] The voltage signal IRI1_OUT output by the transimpedance amplifier module 300 is connected to the AD sampling module 400, such as Figure 6As shown, the AD sampling module 400 of this embodiment adopts a 24-bit high-precision AD sampler AD7124-8BCPZ, and the voltage signal IRI1_OUT output by the transimpedance amplifier module is connected to the AIN0 / IOUT / VBIAS pin, and the collected voltage signal output by the transimpedance amplifier circuit is converted into a digital signal and transmitted to the processing module 500 for export.

[0044] like Figure 7 As shown, the processing module 500 of this embodiment adopts a single-chip microcomputer of model GD32F103VBT6D, and its pins PB12-PB15 and PD8 are connected to the AD sampling module 400 to receive the diode voltage signal collected by the AD sampling module, and the pins PD12-PD15 are connected to the analog switch 120 to control the analog switch to reversely apply the voltage polling to the RGB light-emitting diodes, and the pins PC7-PC9 and PA8-PA10 are connected to the power module 100 to control the power module to control the voltage of the light-emitting diodes.

[0045] The voltage signal of the RGB light-emitting diode is detected by the above test device. The serial port software of the microcontroller calculates and derives the leakage current of the RGB light-emitting diode under the detection voltage through Ohm's law, as shown in the following table.

[0046] Through verification of multiple sets of data, it is found that the measurement accuracy of the measurement device used in this embodiment can reach 0.05uA.

[0047]

[0048]

[0049] In this document, the directions or positional relationships indicated by terms such as "up", "down", "front", "back", "left", "right", "top", "bottom", "inside", "outside", "vertical", and "horizontal" are based on the directions or positional relationships shown in the accompanying drawings and are only for the clarity of the technical solution and the convenience of description. Therefore, they should not be understood as limitations on the present invention.

[0050] In this document, the terms "comprises," "comprising," or any other variations thereof, are intended to cover a non-exclusive inclusion of elements other than those listed and may also include additional elements not expressly listed.

[0051] The above are only specific implementations of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A light emitting diode leakage current measuring device, characterized in that: Including power module, transimpedance amplifier module, AD sampling module and processing module, A power supply module for providing a reverse bias voltage to the light emitting diode, wherein the power supply module is electrically connected to the electrode of the light emitting diode through an analog switch and applies a reverse voltage to the light emitting diode in a polling manner; A transimpedance amplification module for converting a current signal of a light-emitting diode into a voltage signal, wherein the transimpedance amplification module adopts a transimpedance amplification circuit including a transimpedance amplifier, and an input end of the transimpedance amplification circuit is electrically connected to a common end of the light-emitting diode; The AD sampling module is electrically connected to the output end of the transimpedance amplifier circuit and samples the voltage signal converted by the light-emitting diode into a digital signal; The processing module is connected to the power supply module, the analog switch and the AD sampling module for communication, processes the power supply circuit signal and exports the light emitting diode leakage current data measured by the AD sampling module.

2. The light emitting diode leakage current measuring device according to claim 1, characterized in that: The power module adopts a 16-bit adjustable reference voltage source with an adjustable voltage value of 0 to 2.5V. The output of the reference voltage source is connected to a voltage amplification module, and the voltage amplification module adopts a voltage amplification circuit to amplify and output the output voltage of the power module.

3. The light emitting diode leakage current measuring device according to claim 2, characterized in that: The voltage amplifier circuit adopts TP1252-SR as a high-voltage operational amplifier, and a triode is arranged at the output end of the voltage amplifier circuit.

4. The light emitting diode leakage current measuring device according to claim 1, characterized in that: The transimpedance amplifier circuit is provided with a feedback resistor connected in parallel with the transimpedance amplifier, and the ratio between the feedback resistor and the input resistor of the transimpedance amplifier is adjusted to adjust the amplification factor of the transimpedance amplifier.

5. The light emitting diode leakage current measuring device according to claim 1, characterized in that: The transimpedance amplifier uses OPA381AIDGKR and GS8552-SR connected in series.

6. The light emitting diode leakage current measuring device according to claim 1, characterized in that: The AD sampling module adopts a 24-bit AD sampler.

7. The light emitting diode leakage current measuring device according to claim 1, characterized in that: The processing module adopts a single chip microcomputer.

8. A light emitting diode leakage current measuring device according to any one of claims 1 to 7, characterized in that: The light emitting diode is an RGB light emitting diode, and the power supply module outputs two constant voltage circuits, wherein a 20V reference voltage is provided to the red lamp beads of the RGB light emitting diode, and a 10V reference voltage is provided to the green and blue lamp beads of the RGB light emitting diode.

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