JPS6485788A - Power transmission mechanism - Google Patents

Abstract

PURPOSE:To make a device compact by providing planetary gears which are engaged with a sun gear which is a drive element, and a first member to be driven to which the rotation of the drive element is transmitted during its normal rotation through the planetary gear and a second member to be driven to which the rotation is transmitted through a rotor which is formed integrally with the planetary gear during the reversed rotation of the sun gear. CONSTITUTION:When a carriage 1 is moved forward, a motor rotates in a normal direction and a drive element 21 normally rotates counter-clockwise. Then a rewinding gear 30 rotates counter-clockwise through a sun gear 23 and a planetary gear 26. Consequently, the rotating force is applied to a takeup member 16 in a ribbon winding direction. When paper is fed, the planetary gear 26 revolves counter-clockwise following the reversing of the drive element 21, and is separated from the rewinding gear 30. Then the planetary gear is engaged with an intermeshing gear 37a and rotates integrally with a rotor 35 in the same direction. Consequently, an oscillating element 39 rotates counter-clockwise and this causes its engagement protrusion 39a to move to a direction where it is separated from the arm 4b of an oscillating lever 4. As a result, the oscillating lever 4 rotates counter-clockwise and a printing head 5 leaves the printing head 5.