Abstract: There is disclosed an optical disk unit. Optical parts, including a laser unit and objective, are integrally mounted on a bobbin, and focusing coils and tracking and feed coils are mounted on the bobbin. The bobbin is resiliently supported, and is slidable along guide shafts extending radially of an optical disk loaded on the optical disk unit. The bobbin is moved by the focusing coils and the tracking and feed coils, thereby effecting a focusing drive, a tracking drive and a feed drive. With this construction, the optical disk unit can be compact in size, and light in weight.

Abstract: A dot-matrix impact printer includes a print head in a housing for printing a recording sheet fed around a platen. The recording sheet is pressed against the platen by a sheet presser roller. A roller cover or a flap is disclosed as a sound insulating wall closely to the sheet presser roller and has an edge held against the housing. The space above the print head is closed by the housing, the platen, the sheet presser roller, and the platen, so that the impact noise produced when the printer is in operation will not leak out of the housing, while at the same time the recording sheet fed around the platen is not blocked by the closure mechanism.

Abstract: A dot matrix printer of a dispersion printing type in which a printing noise is suppressed and dots arranged in longitudinal rows are driven while shifting the timing for every print wire dot. The present dot matrix printer is characterized by a construction in which respective print wires are driven at different timings within one pitch, and a space around a print head is surrounded by a housing and a platen, and a sound generated in the space is transmitted outside through walls. Further, the present dot matrix printer is characterized in that there is provided a memory storing printing intervals among the whole dots and print head conduction time, and the print head is driven in accordance with information read out of said memory in order to correct deviation of dot rows arranged in a longitudinal direction of the print head from perpendicularity.