Abstract: A positioning control servo uses a digital feedback control system and an analog feedback control system, both simultaneously generating control signals to a servo summing node. The digital system derives negative feedback from velocity values which are raised to any programmed exponential value according to a linear velocity profile. The analog system feedback signals provide a non-linear velocity profile and fine position adjustment and dominates control at the servo end of travel. Interface control is provided from multiplexing a single digital feedback control system with a plurality of servo systems. The interface control selects a unique velocity profile in a digital system for each particular servo system. No switching is required between the digital and analog systems because both have continuous input to the servo summing node.

Abstract: A high-speed printer, such as a daisy wheel printer, utilizes a carriage which transports a printing font, such as a daisy wheel, laterally along a print line adjacent a paper-supporting platen. An ink ribbon is supported on the machine frame rather than the printing font carriage and is positioned between the daisy wheel and the platen. This ribbon is adjusted so that, as the printing font progresses along a print line, it impacts the ribbon along the line which is slanted relative the lengthwise axis of the ribbon. When plural such slanted printing tracks are overlapped along the length of the ribbon, efficient use is made of the ribbon without incurring problems associated with a narrowed ribbon. In addition, the slanted ribbon impact line permits the ribbon to be mounted on the machine main frame rather than on the font carriage while still permitting a minimum of over-impacting on the ribbon, all while eliminating the requirement of rapid ribbon movement during carriage return.

Abstract: An apparatus adjusts the angular orientation of a moving carriage carrying a type font in a true font, stop-to-print, moving head high speed printer. This rotational adjustment provides a simple but accurate paper thickness adjustment which simplifies the printer construction and increases its reliability.

Abstract: In a solenoid driven hammer for an impact printer, the armature, which is driven by the magnetic field provided by the solenoid's coil, is integral with the hammer which strikes a printing element on a print wheel. The shape of the pole piece in the solenoid conforms to the shape of the leading surface of the armature to provide a magnetic force field that is of constant strength as the armature is propelled toward the pole piece when the solenoid coil is energized. The hammer, being unitary with the armature, is thereby propelled against the printing element. As the hammer rebounds after striking the printing element, the armature strikes a polyurethane cushion which absorbs substantially all of the energy of the armature/hammer unit, thereby bringing the unit to a complete stop so that the next stroke may be quickly commenced.