Sony Corp. said Monday that it plans to invest about $1.21 billion to double its production of image sensors used in digital cameras and smart phones, as the popularity of those devices continues to rise worldwide.

The investment includes the electronics giant’s planned repurchase of a factory that it sold to Toshiba Corp. in 2007 for 90 billion yen. Until now, the factory has primarily been used to make processors for Sony’s PlayStation 3 game console. But Tokyo-based Sony said it will refurbish the facility so that it can meet growing demand for imaging sensors. The company hopes to double capacity to 50,000 wafers per month by the end of March 2012.

Sony uses its sensors, branded “Exmor” and “Exmor R,” in its own cameras and also sells these parts to other camera and cell phone manufacturers. The sensors are designed to make photos taken in dimly lit conditions appear brighter and crisper. Sales of Sony sensors helped lift sales in its semiconductor division by double-digits in its fiscal second quarter ended Sept. 30.

The company leads the market in imaging sensors. In addition, Sony’s earnings have been buoyed by success in its personal computer and PlayStation divisions, even as sales of its televisions have slowed.

The company said it will partially fund the investment using government subsidies that reward companies for making their businesses more environmentally friendly.

Shares of Sony fell 6 cents to $35.51 during afternoon trading.