* Question
| Characteristics and applications of infrared light-emitting diodes |
* Answer
| Infrared remote control has been widely used in color TVs, audio systems and various household appliances.The remote control’s control distance is generally 6 to 8 meters, which is very convenient to use.Due to the large amount of infrared remote control, its infrared transmitting and receiving circuits have complete supporting devices. These devices are not only low-priced and reliable, but also extremely simple.Commonly used infrared light-emitting diodes (such as SE303•PH303) have a similar shape to LEDs.The triode BG is used as a switch.
When a driving signal is applied to the base, the BG tube is saturated and turned on, and the infrared illuminating tube D is also working in a forward direction to emit infrared light (near infrared ray of about 0.93 μm).Since the effective transmission distance of the pulsating light (modulated light) is proportional to the peak current of the pulse, it is only necessary to increase the peak current Ip as much as possible to increase the emission distance of the infrared light.The method of increasing Ip is to reduce the pulse duty ratio, that is, the width τ of the compression pulse. Common infrared light-emitting diodes are divided into three categories: low power (1mW to 10mW), medium power (20mW to 50mW), and high power (50mW to 100mW or more).When using different power infrared light-emitting diodes, the drive tube of the corresponding power should be configured.There are two ways to transmit and receive infrared rays, one is direct type, and the other is reflective. |
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