Gear mechanism with an idler gear, a gear mechanism with a device for eliminating backlash between gears, and a motor driving mechanism

A gear mechanism comprising a driving gear, a driven gear and an idler gear which is in mesh with said driving gear and said driven gear,

• wherein said idler gear includes a first spur gear and a second spur gear which are positioned adjacent to each other in an axial direction and are generally centered about a common axis, radial teeth of said first spur gear and radial teeth of said second spur gear being in the same shape, pitch and the number of teeth;
• wherein said first spur gear and said second spur gear are biased to rotate in opposite directions;
• and
• wherein said first spur gear and said second spur gear are connected and configured so as to be moveable relative to each other by a predetermined amount in a radial direction normal to said axial direction while maintaining said first spur gear and said second spur gear in mesh with said driving gear and said driven gear,
• said gear mechanism further comprising a biasing device which biases said first spur gear and said second spur gear to rotate in said opposite directions, said biasing device comprising:
• at least one resilient arm formed on one of said first spur gear and said second spur gear, one end of said resilient end being integral with said one of said first spur gear and said second spur gear, the other end of said resilient arm serving as a free arm, wherein said resilient arm is deformable resiliently in a direction to move said free end in a radial direction;
• and
• at least on arm-engaging recess formed on the other of said first spur gear and said second spur gear so that an engaging protrusion formed on said free end of said resilient arm is engaged in said arm-engaging recess, said arm-engaging recess including a resilient arm bending portion extending in a direction inclined to a circumferential direction of said other of said first spur gear and said second spur gear;
• wherein said radial teeth of said first spur gear and radial teeth of said second spur gear overlap each other in a circumferential direction of said idler gear when said idler gear is in a free state when said idler gear is disengaged from said driving gear and said driven gear;
• and
• wherein said free end of said resilient arm moves in said resilient arm bending portion of said arm-engaging recess therealong to deform said resilient arm to thereby bias said first spur gear and said second spur gear to rotate in said opposite directions when said driving gear and said driven gear are brought into mesh with said idler gear with respective tooth traces of said first spur gear and said second spur gear being substantially aligned with each other.

A device for eliminating backlash between two gears meshing with each other, wherein one of said two gears is an idler gear which comprises a first spur gear and a second spur gear which are positioned adjacent to each other in an axial direction and generally centered about a common axis, radial teeth of said first spur gear and radial teeth of said second spur gear being identical in shape, pitch and the number of teeth,

• wherein said backlash eliminating device comprises a biasing device which biases said first spur gear and said second spur gear to rotate in opposite directions,
• said biasing device comprising:
• at least one resilient arm formed on one of said first spur gear and said second spur gear, one end of said resilient arm being integral with said one of said first spur gear and said second spur gear, the other end of said resilient arm serving as a free end, wherein said resilient arm is deformable resiliently in a direction to move said free end in a radial direction;
• and
• at least one arm-engaging recess formed on the other of said first spur gear and said second spur gear so that an engaging protrusion formed on said free end of said at least one resilient arm is engaged in said arm-engaging recess, said arm-engaging recess including a resilient arm bending portion extending in a direction inclined to a circumferential direction of said other of said first spur gear and said second spur gear;
• wherein said radial teeth of said first spur gear and said radial teeth of said second spur gear overlap each other in a circumferential direction of said idler gear when said idler gear is in a free state wherein said idler gear is disengaged from the other of said two gears;
• and
• wherein said free end of said resilient arm moves in said resilient arm bending portion of said arm-engaging recess therealong to deform said resilient arm to thereby bias said first spur gear and said second spur gear to rotate in said opposite directions when the other of said two gears is brought into mesh with said idler gear with respective tooth traces of said first spur gear and said second spur gear being substantially aligned with each other.

A motor driving mechanism having a driving gear, a driven gear and an idler gear which is in mesh with said driving gear and said driven gear, rotation of said driving gear being transferred to said driven gear via said idler gear, said driving gear being driven by a motor rotation, rotation of said driven gear causing a driven member to move,

• wherein said idler gear comprises a first spur gear and a second spur gear which are positioned adjacent to each other in an axial direction and generally centered about a common axis, radial teeth of said first spur gear and radial teeth of said second spur gear having the same shape, pitch and the number of teeth;
• wherein said first spur gear and said second spur gear are biased to rotate in opposite directions;
• and
• wherein said first spur gear and said second spur gear are connected and configured so as to be movable relative to each other by a predetermined amount in a radial direction normal to said axial direction while maintaining said first spur gear and said second spur gear in mesh with said driving gear and said driven gear.

A motor driving mechanism having a motor and two gears meshing with each other, rotation of said motor being transferred to a driven member via said two gears,

• wherein one of said two gears is an idler gear which comprises a first spur gear and a second spur gear which are positioned adjacent to each other in an axial direction and generally centered about a common axis, radial teeth of said first spur gear and radial teeth of said second spur gear having the same shape, pitch and the number of teeth;
• wherein said motor driving mechanism comprises a biasing device which biases said first spur gear and said second spur gear to rotate in opposite directions, said biasing device including at least one resilient arm formed on one of said first spur gear and said second spur gear, one end of said resilient arm being integral with said one of said first spur gear and said second spur gear, the other end of said resilient arm serving as a free end, wherein said resilient arm is deformable resiliently in a direction to move said free end in a radial direction;
• and at least one arm-engaging recess formed on the other of said first spur gear and said second spur gear so that an engaging protrusion formed on said free end of said resilient arm is engaged in said arm-engaging recess, said arm-engaging recess including a resilient arm bending portion extending in a direction inclined to a circumferential direction of said other of said first spur gear and said second spur gear;
• wherein said radial teeth of said first spur gear and said radial teeth of said second spur gear overlap each other in a circumferential direction of said idler gear when said idler gear is in a free state where said idler gear is disengaged from the other of said two gears;
• and
• wherein said free end of said resilient arm moves in said resilient arm bending portion of said arm-engaging recess therealong to deform said resilient arm to thereby bias said first spur gear and said second spur gear to rotate in said opposite directions when the other of said two gears is brought into mesh with said idler gear with respective tooth traces of said first spur gear and said second spur gear being substantially aligned with each other.

An idler gear having a first spur gear and a second spur gear,

• said first spur gear comprising an axial cylindrical rib centered about an axis of said first spur gear;
• said second spur gear comprising an axial circular opening in which said cylindrical rib is loosely fitted so that said second spur gear is rotatable about said cylindrical rib relative to said first spur gear;
• wherein radial teeth of said first spur gear and radial teeth of said second spur gear are the same in shape, pitch and the number of teeth;
• and
• wherein said idler gear includes a biasing device which biases said first spur gear and said second spur gear to rotate in opposite directions,
• said biasing device comprising:
• at least one resilient arm formed on one of said first spur gear and said second spur gear, one end of said resilient arm being integral with said one of said first spur gear and said second spur gear, the other end of said resilient arm serving as a free end, wherein said resilient arm is deformable resiliently in a direction to move said free arm in a radial direction;
• and
• at least one arm-engaging recess formed on the other of said first spur gear and said second spur gear so that an engaging protrusion formed on said free end of said at least one resilient arm is engaged in said arm-engaging recess, said arm-engaging recess including a resilient arm bending portion extending in a direction inclined to a circumferential direction of said other of said first spur gear and second spur gear;
• wherein said radial teeth of said first spur gear and said radial teeth of said second spur gear overlap each other in a circumferential direction of said idler gear when said idler gear is in a free state wherein said idler gear is disengaged from another gear;
• and
• wherein said free end of said resilient arm moves in said resilient arm bending portion of said arm-engaging recess therealong to deform said resilient arm radially to thereby bias said first spur gear and said second spur gear to rotate in said opposite directions when another gear is brought into mesh with said idler gear with respective tooth traces of said first spur gear and said second spur gear being substantially aligned with each other.

A gear mechanism comprising a driving gear, a driven gear and an idler gear which is in mesh with said driving gear and said driven gear,

• wherein said idler gear includes a first spur gear and a second spur gear which are positioned adjacent to each other in an axial direction and are generally centered about a common axis, radial teeth of said first spur gear and radial teeth of said second spur gear being the same in shape, pitch and the number of teeth;
• wherein said first spur gear and said second spur gear are biased to rotate in opposite directions;
• wherein said first spur gear and said second spur gear are connected so as to be relatively moveable in a radial direction normal to said axial direction while maintaining said first spur gear and said second spur gear in mesh with said driving gear and said driven gear;
• wherein said first spur gear rotates at a fixed position without moving in a plane normal to the rotational axis thereof, and wherein said second spur gear rotates at an unfixed position relative to said first spur gear in a plane normal to the rotational axis of said first spur gear;
• wherein said first spur gear comprises a cylindrical rib centered about the rotational axis thereof;
• and
• wherein said second spur gear comprises a circular opening in which said cylindrical rib is loosely fitted, a range of movement of said second spur gear in said radial directions with respect to said first spur gear being defined by a gap between an inner peripheral surface of said cylindrical rib.

A gear mechanism comprising a driving gear, a driven gear and an idler gear which is in mesh with said driving gear and said driven gear,

• wherein said idler gear includes a first spur gear and a said second spur gear which are positioned adjacent to each other in an axial direction and are generally centered about a common axis, radial teeth of said first spur gear and radial teeth of second spur gear being the same in shape, pitch and the number of teeth;
• wherein said first spur gear and said second spur gear are biased to rotate in opposite directions;
• wherein said first spur gear and said second spur gear are connected so as to be relatively moveable in a radial direction to said axial direction while maintaining said first spur gear and said second spur gear in mesh with said driving gear and said driven gear;
• said gear mechanism further comprising a biasing device which biases said first spur gear and said second spur gear to rotate in said opposite directions, said biasing device comprising:
• at least one resilient arm formed on one of said first spur gear and said second spur gear, one end of said resilient arm being integral with said one of said first spur gear and said second spur gear, the other end of said resilient arm serving as a free end, wherein said resilient arm is deformable resiliently in a direction to move said free end in a radial direction;
• and
• at least one arm-engaging recess formed on the other of said first spur gear and said second spur gear so that an engaging protrusion formed on said free end of said resilient arm is engaged in said arm-engaging recess, said arm-engaging recess including a resilient arm bending portion extending in a direction inclined to a circumferential direction of said other of said first spur gear and said second spur gear;
• wherein said radial teeth of said first spur gear and said radial teeth of said second spur gear overlap each other in a circumferential direction of said idler gear when said idler gear is in a free state when said idler gear is disengaged from said driving gear and said driven gear;
• and
• wherein said free end of said resilient arm moves in said resilient arm bending portion of said arm-engaging recess therealong to deform said resilient arm to thereby bias said first spur gear and said second spur gear to rotate in said opposite directions when said driving gear and said driven gear are brought into mesh with said idler gear with respective tooth traces of said first spur gear and second spur gear being substantially aligned with each other.