A print head protection device is used with an inkjet printer having a print head adapted for elevating. A roller is mounted upstream of the print heads and above the process path a predetermined distance. A cover on the roller outer surface contacts the sheet lead edge if sheet curl exceeds a set curl range. The cover will cause rotation of the roller by engaging the sheet. A rotary encoder is mounted for synchronous rotation with the roller. The rotary encoder generates a signal in response to rotation of the roller, raising the print head to preclude damage. Alternately, the sheet can be discarded.