## Overview of the RPR-06-R The **RPR-06-R** is a reflective-type photointerrupter (also known as an optical sensor) manufactured by ROHM Semiconductor. It integrates an infrared light-emitting diode (LED) and a high-sensitivity phototransistor into a single compact package. --- ### 1. Key Internal Components | Component | Function | Characteristics | | :--- | :--- | :--- | | **Infrared LED** | Light Source | Emits infrared light toward an object. | | **Phototransistor** | Receiver | Detects reflected light and converts it into an electrical signal. | | **Daylight Filter** | Protection | Often includes a filter to reduce interference from ambient visible light. | --- ### 2. Technical Specifications Below are the typical electrical and optical ratings for the RPR-06-R: | Parameter | Symbol | Maximum Rating | | :--- | :--- | :--- | | **Forward Current (LED)** | $I_F$ | 50 mA | | **Reverse Voltage (LED)** | $V_R$ | 5 V | | **Collector-Emitter Voltage** | $V_{CEO}$ | 30 V | | **Collector Current** | $I_C$ | 30 mA | | **Operating Temperature** | $T_{opr}$ | -25°C to +85°C | | **Detection Distance** | $d$ | 4 mm to 6 mm (optimal) | --- ### 3. Operating Principle 1. **Emission:** The infrared LED emits a beam of light. 2. **Reflection:** When an object passes in front of the sensor within its detection range, the light reflects off the object's surface. 3. **Detection:** The phototransistor receives the reflected IR light. 4. **Output:** The phototransistor becomes conductive, allowing current to flow from the collector to the emitter, which can be read as a "LOW" or "HIGH" logic signal by a microcontroller. --- ### 4. Typical Application Circuit To use the RPR-06-R, you generally need two resistors: one to limit current for the LED and one to act as a pull-up/down for the phototransistor. ```cpp // Logic Example: // 1. LED Anode connected to VCC through 220-ohm resistor. // 2. Phototransistor Collector connected to VCC. // 3. Phototransistor Emitter connected to a 10k resistor to Ground. // 4. Tap the signal between the Emitter and the 10k resistor. void setup() { pinMode(2, INPUT); // Signal pin from RPR-06-R } ``` --- ### 5. Common Uses * **Paper Detection:** Used in printers and fax machines to sense paper presence. * **Rotation Sensing:** Combined with a reflective disk to measure RPM (Tachometer). * **Limit Switches:** Non-contact detection of mechanical arm positions. * **Object Counting:** Counting items moving on a conveyor belt.