Anti-backlash gear drive

An anti-backlash gear drive, adapted for use with a gear train which includes a rotatable first driver gear, a movable, toothed driven member engaged with said rotatable first driver gear, and a source of rotary motion driving power to which is connected a rotatable second driver gear, wherein said source of rotary motion driving power can be electively activated and, when activated, rotates said second driver gear, comprising:

• a. means for interconnecting said rotatable second driver gear to said rotatable first driver gear, whereby when said rotatable second driver gear is rotated by said source of rotary motion driving power, then said rotatable first driver gear is rotated in a preselected direction and at a preselected speed, and thereby said first driver gear moves said movable, toothed driven member with which said first driver gear is engaged, wherein this means includes:
• (1) a rotatable first shaft having a first and a second end, with said rotatable first driver gear mounted at said first end thereof;
• (2) and, a rotatable first driven gear fixedly mounted on said second end of said rotatable first shaft, with said rotatable first driven gear engaged with said rotatable second driver gear;
• b. means for preventing backlash between said rotatable first driver gear and said movable, toothed driven member, wherein this backlash preventing means includes:
• (1) a rotatable anti-backlash driven gear that is engaged with said movable, tooth driven member, wherein said anti-backlash driven gear and said rotatable first driver gear have a ratio of 1-to-1 and are rotatable in the same direction;
• (2) and, means for loading said rotatable anti-backlash driver gear with a force of preselected magnitude against said movable, tooth driven manner, wherein this force-loading means is operatively associated with said rotatable anti-backlash driven gear;
• and
• c. means for imparting rotary motion to said force-loaded anti-backlash driven gear, with said imparted rotary motion being in the same direction and at the same speed at which said rotatable first driver gear is being driven, and wherein this rotary motion imparting means is operatively associated with said force-loaded anti-backlash driver gear;
• and also wherein this means includes:
• (1) a rotatable third driver gear fixedly mounted on said rotatable first shaft at a location intermediate of said rotatable first driver gear and of said rotatable first driven gear;
• (2) a rotatable idler gear engaged with said rotatable third driver gear;
• (3) a rotatable second driver gear engaged with said rotatable idler gear;
• (4) a rotatable second shaft on which is fixedly mounted said rotatable second driven gear;
• and
• (5) means for interconnecting said rotatable second shaft and said rotatable anti-backlash driven gear;
• whereby when said second driver gear is rotated by said source of rotary motion driving power, then said first driven gear, said first shaft, said third driver gear, said first driver gear, said second driven gear, said second shaft, said means for interconnecting said rotatable second shaft and said rotatable anti-backlash driven gear, and said anti-backlash driven gear all rotate in the same direction;
• and whereby said force-loaded rotating anti-backlash driven gear rotates in the same direction and at the same speed as said rotating first driver gear, and thereby said force-loaded anti-backlash driven gear prevents backlash between said first driver gear and said movable, toothed driven member with which said first driver gear is engaged.