Matrix printer using magnetically operated needles - has double guide plate to minimise effect of abrasive action wearing guide holes

摘要

The matrix printer uses a set of needles arranged in a vertical column to form the dots which constitute a printed character. Each needle is controlled by an electromagnet. The set of electromagnets are arranged in a fan behind the printing head. The needles are brought together by two guide plates so that their ends nearest to the printing area are parallel one above the other. The parts of the needles which are curved are protected by coil springs made of bronze or beryllium. The double system of guide plates helps to prevent the guide holes nearest to the printing becoming elliptical with wear. This in turn prevents the degradation of the printed character. The coil springs prevent sharp bends in the needles which can otherwise cause damage.