Korean retailer Emart had a problem: their sales declined during the lunch hour. To counter this, they developed a time sensitive QR code that relies upon the position of the sun to create a shadow based QR code.
Springwise has more:
Dubbed “Sunny Sale,” Emart’s effort involved setting up a series of what it calls “shadow” QR codes that depend on peak sunlight for proper viewing and were scannable only between 12 and 1 pm each day. Successfully scanning a code took consumers to a dedicated home page with special offers including a coupon worth USD 12. Purchases could then be made via smartphone for delivery direct to the consumer’s door.