Method and device for detecting nuts in trunk cover plate production

The invention relates to a method and device for detecting whether nuts mounted on a base plate are missed in trunk cover plate production. Light-guide fibers are used for transmitting reflected light on the nuts to photoelectric converting elements which convert the reflected light to electric signals, then the electric signals are sent to judging units, the strength of the reflected light is judged according to the strength of the electric signals, and therefore whether the nuts are missed can be known. The method and device solve the problem the detection is difficult due to the facts that the nuts are large in number and small in size, and the distances between the nuts are small, and the missing mounting detection problem is solved through the economical method.