Abstract: A printer for printing by a print head having a plurality of recording elements arranged, includes a scan unit for scanning the print head in a different direction from the direction of arrangement of the recording elements, a memory for storing print data, a write unit for writing the print data into the memory, and a read unit for reading the print data written in the memory in synchronism with the scan of the print head by the scan means for supplying the print data to the print head. The memory has continuous addresses relative to the arrangement of the print data corresponding to the direction of arrangement of the recording elements.

Abstract: Random masks each having a given size and defining a random array of non-record pixel locations and record pixel locations are placed in association with record areas in mask registers. Using the placed masks, record data is thinned-out and supplied to a recording head. An image is then recorded. Thus, since thinning-out masks do not have periodicity, any inherent density nonuniformity loses periodicity. Consequently, high-definition images can be produced.

Abstract: A duty factor of a pulse is set in accordance with duty factor data at each timing determined by a timer function to change the duty factor of the pulse in one step of the drive of a stepping motor in order to control the motor power in open loop.

Abstract: A coupling device comprising two bosses for respectively inserting therein each end of two shafts to be connected, a coupling member which is made of a resilient material and covers the bosses and a casing to fit the coupling member therein. The bosses have a plurality of toothed portions formed on outer periphery thereof and the coupling member has toothed portions identical in number and shape to the toothed portions of the bosses at inner periphery thereof so that the two bosses and coupling member are engaged with each other.

Abstract: According to the present invention, a metal sheet is prepared by subjecting an Al slab, containing at least one element capable of peritectic reaction with Al, such as Ti, Zr and Mo, the amount of the element incorporated in the slab being 0.05 to 0.4% by weight when one element is incorporated and when two or more elements are incorporated, the amount of at least one element incorporated therein being 0.05 to 0.4% by weight and the total amount of the elements incorporated being not higher than 0.5% by weight, to a soaking heat treatment, hot-rolling the slab and then cold-rolling the hot-rolled slab. According to the present invention, the properties required for such metal sheet, namely the strength and formability, can be remarkably improved, and by the hardening treatment, the adherence between fins and tubes can be improved and the heat transfer efficiency can be remarkably elevated in the heat exchangers. Thus, according to the present invention, practically applicable hard thin fins can be provided.