Paper warping detection device

A paper warping detection device comprising:

• an input tray for loading a plurality of pieces of paper to be fed;
• a processor for storing a first threshold;
• a first emitting unit disposed at a front end of the input tray that forms a first angle with the input tray, and then emits a first ultrasonic beam toward the input tray in an obliquely and downward direction;
• a first receiving unit which is disposed at the front end of the input tray and formed a second angle with the input tray for receiving the ultrasonic beam reflected by the paper loaded in the input tray in a direction leaned downward;
• and
• a first analog to digital converter which is electrically connected to the first receiving unit and the processor respectively, for converting the reflected first ultrasonic beam received by the first receiving unit into a first digital signals and outputting the first digital signals to the processor;
• wherein, the first angle is greater than the second angle, and the processor reads the first digital signals outputted by the first analog to digital converter and compares with the first threshold.