Abstract: A device for monitoring and compensating for changes in the flight time of the print hammers of impact printers is disclosed. The flight time of the respectively monitored hammer is calculated from the elapsed time between the moment of firing of a hammer and the moment of impact of the print type carrier against the impact platen. In order to ensure automatic self-adjustment of all print hammers in predetermined test cycles, without the actual printing process itself being affected, and without there being any test imprints on the record carrier, the print type carrier includes, in addition to the standard print types, an additional test type. The impact surface area of the test type is large enough such that no visible imprint is made upon its impact on the record carrier because of the low impact pressure.

Abstract: An electromagnetic actuator for performing an individual stepping, switch or impact movement consists of an electromagnetic actuator and a pivoted or rocking armature moving. The rotational design of the electromagnetic actuator enables only one excitation coil to serve a plurality of magnetic gaps.

Abstract: The continuous type belt is arranged round two rollers, one of which is driven. One straight section of the type belt contacts over its entire length the support designed as a platen.In order to avoid groove on the platen caused by the rotating type belt, and to achieve a distribution of other kinds of wear of the platen over its circumference, a gear motor causes the platen to rotate very slowly (approximately 1 revolution in 72 hours).The platen can also be rotated without a gear motor. For this purpose, the longitudinal axis of the platen is slightly inclined relative to the edge of the type belt. This inclination effects a small movement component in the direction of the platen circumference while the type belt slides along the lateral surface of the platen, said component causing a slow revolution of the platen.

Abstract: A daisy wheel spring disc utilized in conjunction with a daisy wheel print element to control impression. Both the spring disc and the print element have radially extending petals. The print element petals carry a character adjacent their outer extremity. A spring disc petal is associated with each print element petal for which impression is to be controlled. The spring disc petals vary in length relative to the print element petals. The lengths of the spring disc petals depend upon whether the character on the associated print wheel petal has a large or small print surface area. During printing, the spring disc is positioned on the printing side of the print element. When a print element petal is driven out of the plane of the remaining print element petals during printing of a character, the associated spring disc petal will be contacted and will absorb a portion of the energy imparted to the print element petal.

Abstract: In a signal storage apparatus employing a rotating record disk, the resonant frequency of a head carriage assembly is tuned to the rotational speed of the record disk. The head carriage assembly, in following a record track on the record disk, has to accommodate record disk rotational perturbations; i.e., run out, eccentric mounting, etc. Such variations are better accommodated in the head carriage assembly by electrically tuning the head carriage assembly to the rotation of the record disk. In a voice coil head assembly actuator, a pair of opposing coils carry equal current amplitudes. These equal current amplitudes are adjusted to rotational speed of the record disk to thereby continuously tune the head carriage assembly to the record disk rotation.