| 摘要 |
PURPOSE:To prevent the lowering in printing grade, by a simple constitution such that a ribbon tension control means for changing the tension of an ink ribbon corresponding to a recording pattern is provided to an ink ribbon supply apparatus. CONSTITUTION:Two rubber rollers 50, 51 freely rotatable around vertical shafts and brought into contact under pressure with each other at the peripheral surfaces thereof are provided to the bottom surface of a ribbon cassette 11. An ink ribbon 10 receives ribbon tension fT by the friction force between two rubber rollers 50, 51 when passes between both rollers. The ribbon tension fT imparted can be controlled only by the number of rotations of a ribbon take-up motor 20 and, by changing the number of rotations, said tension fT can be controlled to proper force stronger than the bonding strength F of the ink ribbon 10. Therefore, even when the number of dots to which voltage is applied are many and the bonding strength of the ink ribbon and a sheet increases, control can be easily performed so that the ribbon tension always become a value larger than bonding strength and the lowering in printing grade due to the slackening of the ink ribbon can be prevented. |
