The **E3JK-R4M1** is a popular industrial photoelectric sensor manufactured by Omron (and various compatible brands). It is a **retro-reflective** type sensor, meaning it emits a light beam that must bounce off a reflector to be detected by the receiver housed in the same unit. --- ### 1. Key Technical Specifications | Feature | Specification | |:---|:---| | **Sensing Method** | Retro-reflective (Requires a reflector) | | **Sensing Distance** | Up to 4 meters (depending on reflector size) | | **Supply Voltage** | 12 to 240 VDC / 24 to 240 VAC (Multi-voltage) | | **Output Type** | Relay Output (SPDT - Single Pole Double Throw) | | **Switching Capacity** | 3A at 250 VAC | | **Response Time** | 20 ms maximum | | **Light Source** | Infrared LED | | **Indicator** | Red LED (Light reception indicator) | --- ### 2. Internal Electronic Components The E3JK-R4M1 is complex because it integrates AC-to-DC conversion and logic into a single housing. * **Emitter & Receiver:** Contains an Infrared (IR) LED as the light source and a phototransistor/photodiode as the detector. * **Power Supply Circuit:** Includes a bridge rectifier and voltage regulator to allow the device to run on both AC and DC power. * **Internal Relay:** Unlike NPN/PNP sensors that use solid-state transistors for output, this model uses a **mechanical relay**. This allows it to switch higher current loads directly. * **Sensitivity Potentiometer:** Usually located on the back or side, allowing the user to adjust the threshold for detection. --- ### 3. Wiring Configuration (5-Wire System) The device typically uses a 5-wire color-coded cable: | Wire Color | Function | Description | |:---|:---|:---| | **Brown** | Power (L/+) | Connect to Supply (12-240V) | | **Blue** | Power (N/-) | Connect to Supply (12-240V) | | **White** | Relay Common (COM) | The "Input" side of the switch | | **Black** | Normally Open (NO) | Closes when the beam is broken/made | | **Gray** | Normally Closed (NC) | Opens when the beam is broken/made | --- ### 4. Detection Logic The E3JK-R4M1 can often be configured for two modes: 1. **Light-ON:** The relay activates when the receiver sees the light from the reflector. 2. **Dark-ON:** The relay activates when an object blocks the beam (standard for most security and counting applications). ---