Pictured: Photocoupler plastic reel (left) and paper reel (right)
What is a Photocoupler?
A photocoupler is an electronic component that transfers electrical signals between two isolated circuits using a beam of light. It safeguards sensitive, low-voltage control circuits (like microcontrollers) from dangerous high-voltage spikes, surges, or heavy electrical noise originating from power supplies or motors.
Photocouplers play a hidden but vital role in everyday consumer electronics, primarily inside power blocks, chargers, and appliances that plug directly into a wall outlet. They separate the dangerous, high-voltage AC coming to and from an electrical socket from the safer low-voltage DC that reaches a device.
Photocouplers in Action
Common household devices use photocouplers to function safely and efficiently. Chargers and adaptors for smartphones and laptops use compact Switch-Mode Power Supplies. In these bricks, a photocoupler sits directly on the boundary separating the main wall current from the USB cable. Once the phone or tablet has almost finished charging a feedback loop is triggered, which lights up the photocoupler’s internal LED, sending a flash across the gap to the high-voltage side, ensuring the device receives the exact voltage it needs without risking a high-voltage surge.
Similarly, photocouplers appear in television sets and computer monitors. When put in “Standby Mode”, the action of pressing the “power” or “on” button on the remote activates a microchip that uses a photocoupler to send a safe optical trigger to the main power circuit. The main power system awakens and floods the screen with energy, keeping the delicate computer chips protected from any electrical noise or spikes generated by the TV’s heavy power boards.
Photocouplers are widely used in printers, playing a crucial role in managing physical movement, sensing paper, and protecting internal control electronics from electrical damage.
Photocouplers, also known as optocouplers or optoisolators, frequently come in reels. This formatting is known as tape and reel packaging. It is the industry standard for high-volume automated manufacturing, allowing automated pick-and-place machines to quickly feed, orient, and mount the components onto printed circuit boards (PCBs)
Sharp announces Photocouplers with Paper Reel Packaging
The switch from plastic reels to paper reels reduces CO2 emissions by approximately 35%, based on Sharp research over the full lifecycle of the packaging material from raw material procurement to disposal.
Sharp Semiconductor Innovation Corporation has begun mass production and shipment of photocoupler products using paper reels as packaging material in place of the plastic reels previously used.
Regarding the company’s paper reel rollout for its photocoupler lineup, the <PC817X series> and <PC357N series> have already entered mass production and shipment, while the <PC123X series> is scheduled to begin mass production in October.
