Abstract: A dot line printer has a plurality of print hammers accommodated in a hammer bank, which make dot impressions on a sheet of print paper as the hammer bank reciprocally moves in a print line direction perpendicular to the direction in which the sheet of print paper is fed. To print L dot lines at a time with each of forward and backward movements of the hammer bank, the print hammers are divided into a preselected number of groups so that each group includes N number of print hammers where L and N are integers equal to or greater than 3. The print hammers in each group are displaced one dot line distance from one another in the sheet feeding direction. The print hammers in each group are further displaced in the print line direction by respective predetermined distances from their home positions so that the respective hammers in each group do not impinge upon the sheet of print paper simultaneously.

Abstract: A sound reducing construction for shielding sound in a confined box, the box including a first plate component formed with a first open end portion and a second plate component formed with a second open end portion and accommodating therein a machine which generates the sound, the first plate component being movable with respect to the second plate component. The sound reducing construction comprises: a packing unit having one end fixed to the first open end portion of the first component and having another end portion in contact with the second open end portion when the first component is rested on the second component; and, the first and second open end portions providing stepped portions in conformance with each other. The first and second open end portions define two horizontally extending gaps whose vertical heights are different from each other and a vertically extending gap. The packing unit is positioned in one of the horizontally extending gap.

Abstract: In a control device for an impact printer for performing a printing operation at a first printing speed, a temperature sensing element, provided such that the temperature of an electromagnet unit can be directly or indirectly detected, is operated at a first temperature and restored at a second temperature lower than the first temperature. A controller changes the printing speed to a second printing speed lower than the first printing speed when the temperature sensing element is operated, returns the printing speed to the first printing speed when the element is restored, and changes the operating speed to a third printing speed lower than the second printing speed when the element is operated for a predetermined period of time, whereby the printer is made high in reliability.

Abstract: A cooled print hammer assembly in which a plurality of hammer coils are formed in a resin member having a recess in which is placed a cooling fin. The opened faces of the fins are placed adjacent a plate of the frame of the print hammer assembly so that closed forced-air ducts are defined by the fins and the frame plate. Additionally, partitions may be placed on the sides of the fins so that the external sides of the fins are cooled.