Printer including improved print head control

Abstract

A plurality of lines are printed by the print head of a printer which is moved in a predetermined print direction on a sheet placed on a planar supporting surface wherein the sheet is fed perpendicular to the print direction. The print head is slidably mounted on a guide bar which is supported by a frame parallel to the sheet supporting surface so as to permit moving the lower end of the print head upwardly and downwardly relative to the support surface. The frame is biased in the downward direction normally. During non-print operation, a driving lever moves the frame upwardly to raise the print head to an initial position spaced above the support surface by a predetermined distance where it is maintained. During a print operation, the driving lever engages the frame to drive it upwardly or downwardly with the upward movement against the bias force. When the driving lever engages the frame for moving it downwardly, the driving lever engages to suppress a rapid downward movement of the frame due to the bias force thereby slowly moving the frame downwardly. The driving lever disengages from the frame after the print head lower end lands on the sheet placed on the support surface. Clearance between the lever and frame is detected. A control device responds to a print start signal for activating a driving source to apply the driving lever with a downward driving force for moving the frame downward. The control device responds to the detection signal to deactivate the driving source to terminate the application of downward force to the frame and hold the lever at its stopped position. The control device responds to completion of a print operation of one line on the sheet to activate the driving source for moving the driving lever from its stopped position to engage the frame and move it upwardly.