Abstract: To provide a fastener that is able to prevent the tightening nut from loosening over an extended period. The anti-loosening fastener comprises a bolt that has a head and a shank, where the shank comprises a root-side of a large diameter and an end-side of a small diameter, the root-side has a tightening thread formed on it in one turning direction, the end-side has an anti-loosening thread formed on it in the other turning direction, and the minor diameter of the tightening thread is greater than the major diameter of the anti-loosening thread; a tightening nut is screwed on the tightening thread; and an anti-loosening nut is screwed on the anti-loosening thread with the front end in contact with the rear end of the tightening nut and may have the same outer dimensions as the tightening nut.

Abstract: A pattern erasably written on a black board or a flexible sheet in a meeting is printed to a hard copy through scanning of the pattern by an image sensor which provides an electrical signal relating to the pattern, and printing the pattern on a paper according to said electrical signal. The present print board comprises a housing, a writing sheet or a black board mounted on said housing, an elongated lamp for illuminating an elongated portion of said sheet, an image sensor to provide an electrical signal relating to the pattern on a scanning line on the sheet illuminated by said lamp, means for relatively moving said image sensor to said sheet for full scanning of the pattern, and a printer for providing a hard copy of the pattern with smaller size than said pattern according to said electrical signal from said image sensor.