Detection Method Of LED Light-Emitting Diode

1. Detection of ordinary LED light-emitting diodes (1) Detection with a multimeter. Using a pointer multimeter with a ×10kΩ block can roughly judge whether the LED light-emitting diode is good or bad. Normally, the forward resistance of the diode is tens to 200kΩ, and the reverse resistance is ∝. If the forward resistance value is 0 or ∞, and the reverse resistance value is small or 0, it is easy to be damaged. With this detection method, the luminescence of the luminescent tube cannot be seen on the spot, because ×10k&Omega

LED Light Emitting Diode

1. Detection of ordinary LED light-emitting diodes

Check with a multimeter. Using a pointer multimeter with a ×10kΩ block can roughly judge whether the LED light-emitting diode is good or bad. Normally, the forward resistance of the diode is tens to 200kΩ, and the reverse resistance is ∝. If the forward resistance value is 0 or ∞, and the reverse resistance value is small or 0, it is easy to be damaged. This detection method cannot actually see the luminescence of the luminescent tube, because the ×10kΩ block cannot provide a large forward current to the LED.

If there are two pointer multimeters (preferably the same model), you can better check the light-emitting situation of the LED light-emitting diode. Connect a wire from the "+" post of one of the multimeters to the "-" post of the other meter. The remaining "-" pen is connected to the positive electrode (P area) of the luminous tube under test, and the remaining "+" pen is connected to the negative electrode (N area) of the luminous tube under test. Both multimeters are set to ×10Ω block. Under normal circumstances, it can emit light normally after being connected. If the brightness is very low or even does not emit light, both multimeters can be dialed to ×1Ω. If it is still very dark or even does not emit light, it means that the LED light-emitting diode has poor performance or is damaged. It should be noted that the two multimeters cannot be placed at ×1Ω at the beginning of the measurement, so as to avoid excessive current and damage the LED light-emitting diode.

(2) External power supply measurement. The optical and electrical characteristics of LED light-emitting diodes can be measured more accurately with a 3V regulated source or two dry batteries in series and a multimeter (either pointer or digital). To this end, the circuit can be connected as shown in Figure 10. If the measured VF is between 1.4 and 3V, and the brightness of the light is normal, it means that the light is normal. If VF=0 or VF≈3V is measured and there is no light, it means that the luminescent tube is broken.

2. Detection of infrared LED light-emitting diodes

Due to the infrared LED light-emitting diode, it emits 1-3μm infrared light, which cannot be seen by human eyes. Usually, the emission power of a single infrared LED light-emitting diode is only a few mW, and the angular distribution of the luminous intensity of different types of infrared LEDs is also different. The forward voltage drop of infrared LED is generally 1.3 ~ 2.5V. It is precisely because the infrared light emitted by it is invisible to the human eye, so the detection method using the above-mentioned visible light LED can only determine whether the forward and reverse electrical characteristics of its PN junction are normal, but cannot determine whether its luminescence is normal or not. For this reason, it is best to prepare a photosensitive device (such as 2CR, 2DR type silicon photocell) as a receiver. Use a multimeter to measure the change of the voltage across the battery. To judge whether the infrared LED emits infrared light after adding an appropriate forward current. its measurement circuit.

Semiconductor light-emitting devices include semiconductor LED light-emitting diodes (referred to as LEDs), digital tubes, symbol tubes, meter tubes, and dot matrix displays (referred to as matrix tubes). In fact, each light-emitting unit in the digital tube, the symbol tube, the meter tube and the matrix tube is an LED light-emitting diode.