The **LTHZ-11D-R** is a specific model of an **Infrared (IR) Reflective Sensor** (often referred to as an Optical Interrupter or Photoreflector). These components are widely used for object detection, position sensing, and line tracking in robotics. --- ### 1. Internal Components The LTHZ-11D-R consists of two primary electronic parts housed in a single plastic casing: | Component | Function | Description | | :--- | :--- | :--- | | **Infrared Emitter** | Light Source | An IR LED that emits invisible light at a specific wavelength (typically 940nm). | | **Phototransistor** | Receiver | A light-sensitive transistor that becomes conductive when it detects reflected IR light. | ### 2. Technical Specifications While specific datasheets can vary slightly by manufacturer (like Lite-On), the typical parameters for this series are: * **Input (Emitter):** * Forward Current ($I_F$): ~50mA * Forward Voltage ($V_F$): ~1.2V to 1.6V * **Output (Detector):** * Collector-Emitter Voltage ($V_{CEO}$): ~30V * Collector Current ($I_C$): ~20mA * **Sensing Distance:** Optimized for close-range detection (typically 1mm to 5mm). --- ### 3. Working Principle The device operates on the principle of **reflection**: 1. The **IR LED** constantly emits infrared light. 2. If an object is placed in front of the sensor, the light hits the surface and **reflects** back. 3. The **Phototransistor** receives this reflected light, allowing current to flow from the Collector to the Emitter. 4. If the surface is black (absorbs IR) or no object is present, the phototransistor remains "Off." ### 4. Typical Circuit Connection To use this part in an electronic circuit, you generally need two resistors: one to limit current for the LED and one to act as a pull-up/down for the transistor. ```cpp // Schematic Logic: // [VCC] -- [Resistor 220Ω] -- [Anode (LED) Cathode] -- [GND] // [VCC] -- [Resistor 10kΩ] -- [Collector (Transistor) Emitter] -- [GND] // | // (Signal Output to MCU) ``` --- ### 5. Common Applications * **Line Following Robots:** Detecting the contrast between a white surface and a black line. * **Paper Sensors:** Used in printers to detect if paper is present in the tray. * **Shaft Encoders:** Counting rotations by detecting reflective stickers on a motor shaft. * **Limit Switches:** Non-contact detection of mechanical arm positions.