Detent means for settable print wheels

Claim 2

In a print wheel assembly comprising a frame member including a shaft, said shaft including guide slot means extending into said shaft and opening at the exterior thereof, a print wheel rotatably disposed on said shaft for rotational movement to any one of a plurality of print positions, said print wheel including an annular internal serrated peripheral portion having a plurality of slope-faced teeth in line with said guide slot means, each of said teeth including a clockwise fAce and a counterclockwise face, and non-locking detent means slidably and loosely guided in said guide slot means and spring urged towards said peripheral portion to cooperate with the teeth of said wheel to urge the wheel approximately into any selected print position, said non-locking detent means constituting the sole means for determining the static rotary position of said wheel, the improvement which comprises: said guide slot means comprising at least one pair of complementary guide slots, and said non-locking detent means comprising at least one pair of cooperating detents including a first detent and a second detent each guided in one of said complementary guide slots for movement towards and away from said peripheral portion, said detents each being spring urged for independent movement towards said peripheral portion, the position of said complementary guide slots being so arranged that when the print wheel is at rest approximately at one of said print positions, the first detent of said pair is spaced away from each of said counterclockwise faces and only engages one of said clockwise faces to exert a first positive torque on said print wheel in one direction, and the second detent of said pair is spaced away from each of said clockwise faces and only engages one of said counterclockwise faces for exerting a second positive torque on said print wheel substantially equal in magnitude but opposite in direction to said first torque, whereby the joint action of the detents serves to urge said print wheel precisely into the corresponding print position and hold it there regardless of any side play existing between said detents and their guide slots.

Claim 3

In a print wheel assembly comprising a frame member including a shaft, said shaft including guide slot means extending into said shaft and opening at the exterior thereof, a print wheel rotatably disposed on said shaft for rotational movement to any one of a plurality of print positions, said print wheel including an annular internal serrated peripheral portion having a plurality of slope-faced teeth in line with said guide slot means, each of said teeth including a clockwise face and a counterclockwise face, and non-locking detent means slidably and loosely guided in said guide slot means, and spring urged towards said peripheral portion to cooperate with the teeth of said wheel to urge the wheel approximately into any selected print position, said non-locking detent means constituting the sole means for determining the static rotary position of said wheel, the improvement which comprises: said guide slot means comprising at least one pair of complementary guide slots, and said non locking detent means comprising at least one pair of cooperating detents including a first detent and a second detent each guided in one of said complementary guide slots for movement towards and away from said peripheral portion, said detents each being spring urged for independent movement towards said peripheral portion, the position of said complementary guide slots being so arranged that when the print wheel is at rest approximately at one of said print positions, the first detent of said pair is spaced away from each of said counterclockwise faces and only engages one of said clockwise faces to exert a first positive torque on said print wheel in one direction, and the second detent of said pair is spaced away from each of said clockwise faces and only engages one of said counterclockwise faces for exerting a second positive torque on said print wheel substantially equal in magnitude but opposite in direction to said first torque, whereby the joint action of the detents serves to urge said print wheel precisely into the corresponding print position and hold it there regardless of any side play existing between said detents and their guide slots, said teeth being of even number, said complementary guide slots being constituted as portions of a single straight transaxial opening through the shaft with one detent guided in each end thereof, and the opening being positioned with its centerline offset from the parallel transaxial centerline of the shaft by a slight but measurable amount to effect the cooperation of the detents independently with the clockwise and counterclockwise tooth faces aforesaid.

Claim 4

In a print wheel assembly comprising a frame member including a shaft, said shaft including guide slot means extending into said shaft and opening at the exterior thereof, a print wheel rotatably disposed on said shaft for rotational movement to any one of a plurality of print positions, said print wheel including an annular internal serrated peripheral portion having a plurality of slope-faced teeth in line with said guide slot means, each of said teeth including a clockwise face and a counterclockwise face, and non-locking detent means slidably and loosely guided in said guide slot means, and spring urged towards said peripheral portion to cooperate with the teeth of said wheel to urge the wheel approximately into any selected print position, said non-locking detent means constituting the sole means for determining the static rotary position of said wheel, the improvement which comprises: said guide slot means comprising at least one pair of complementary guide slots, and said non locking detent means comprising at least one pair of cooperating detents including a first detent and a second detent each guided in one of said complementary guide slots for movement towards and away from said peripheral portion, said detents each being spring urged for independent movement towards said peripheral portion, the position of said complementary guide slots being so arranged that when the print wheel is at rest approximately at one of said print positions, the first detent of said pair is spaced away from each of said counterclockwise faces and only engages one of said clockwise faces to exert a first positive torque on said print wheel in one direction, and the second detent of said pair is spaced away from each of said clockwise faces and only engages one of said counterclockwise faces for exerting a second positive torque on said print wheel substantially equal in magnitude but opposite in direction to said first torque, whereby the joint action of the detents serves to urge said print wheel precisely into the corresponding print position and hold it there regardless of any side play existing between said detents and their guide slots, said teeth being of even number, said complementary guide slots being constituted as portions of a single straight transaxial opening through the shaft with one detent guided in each end thereof, and the opening being positioned with its centerline offset from the parallel transaxial centerline of the shaft by a slight but measurable amount to effect the cooperation of the detents independently with the clockwise and counterclockwise tooth faces aforesaid.

Claim 5

In a print wheel assembly comprising a frame member including a shaft and a member located outwardly of said shaft, said member including guide slot means extending into said member and opening towards said shaft, a print wheel rotatably disposed on said shaft for rotational movement to any one of a plurality of print positions, said print wheel including an annular external serrated peripheral portion having a plurality of slope-faced teeth in line with said guide slot means in said outwardly located member, each of said teeth including a clockwise face and a counterclockwise face, and a non-locking detent means slidably and loosely guided in said guide slot means, and spring urged towards said peripheral portion to cooperate with the teeth of said wheel to urge the wheel approximately into any selected print position, said non-locking detent means constituting the sole means for determining the static rotary position of said wheel, the improvement which comprises: said guide slot means comprising at least one pair of complementary guide slots, and said non-locking detent means comprising at least one pair of cooperating detents including a first detent and a second detent each guided in one of said complementary guide slots for movement towards and away from said peripheral portion, said detents each being spring urged for independent movement towards said peripheral portion, the position of said complementary guide slots being so arranged that when the print wheel is at rest approximately at one of said print positions, the first detent of said pair is spaced away from each of said counterclockwise faces and only engages one of said clockwise faces to exert a first positive torque on said print wheel in one direction, and the second detent of said pair is spaced away from each of said clockwise faces and only engages one of said counterclockwise faces for exerting a second positive torque on said print wheel substantially equal in magnitude but opposite in direction to said first torque, whereby the joint action of the detents serves to urge said print wheel precisely into the corresponding print position and hold it there regardless of any side play existing between said detents and their guide slots.

Claim 6

In a print wheel assembly comprising a frame member including a shaft and a member located outwardly of said shaft, said member including guide slot means extending into said member and opening towards said shaft, a print wheel rotatably disposed on said shaft for rotational movement to any one of a plurality of print positions, said print wheel including an annular external serrated peripheral portion having a plurality of slope-faced teeth in line with said guide slot means in said outwardly located member, each of said teeth including a clockwise face and a counterclockwise face, and a non-locking detent means slidably and loosely guided in said guide slot means, and spring urged towards said peripheral portion to cooperate with the teeth of said wheel to urge the wheel approximately into any selected print position, said non-locking detent means constituting the sole means for determining the static rotary position of said wheel, the improvement which comprises: said guide slot means comprising at least one pair of complementary guide slots, and said non-locking detent means comprising at least one pair of cooperating detents including a first detent and a second detent each guided in one of said complementary guide slots for movement towards and away from said peripheral portion, said detents each being spring urged for independent movement towards said peripheral portion, the position of said complementary guide slots being so arranged that when the print wheel is at rest approximately at one of said print positions, the first detent of said pair is spaced away from each of said counterclockwise faces and only engages one of said clockwise faces to exert a first positive torque on said print wheel in one direction, and the second detent of said pair is spaced away from each of said clockwise faces and only engages one of said counterclockwise faces for exerting a second positive torque on said print wheel substantially equal in magnitude but opposite in direction to said first torque, whereby the joint action of the detents serves to urge said print wheel precisely into the corresponding print position and hold it there regardless of any side play existing between said detents and their guide slots.

Claim 7

In a print wheel assembly comprising a frame member including a shaft, said frame member including guide slot means extending into the material of the frame member and opening at the exterior thereof, a print wheel rotatably disposed on said shaft for rotational movement to any one of a plurality of print positions, said print wheel including an annular serrated peripheral portion having a plurality of slope-faced teeth in line with said guide slot means, each of said teeth including a clockwise face and a counterclockwise face, and non-locking detent means slidably and loosely guided in said guide slot means, and spring urged towards said peripheral portion to cooperate with the teeth of said wheel to urge the wheel approximately into any selected print position, said non-locking detent means constituting the sole means for determining the static rotary position of said wheel, the improvement which comprises: said guide slot means comprising at least one pair of complementary guide slots, and said non-locking detent means comprising at least one pair of cooperating detents including a first detent and a second detent each guided in one of said complementary guide slots for movement towards and away from said peripheral portion, said detents each being spring urged for independent movement towards said peripheral portion, the position of said complementary guide slots being so arranged that when the print wheel is at rest approximately at one of said print positions, the first detEnt of said pair is spaced away from each of said counterclockwise faces and only engages one of said clockwise faces to exert a first positive torque on said print wheel in one direction, and the second detent of said pair is spaced away from each of said clockwise faces and only engages one of said counterclockwise faces for exerting a second positive torque on said print wheel substantially equal in magnitude but opposite in direction to said first torque, whereby the joint action of the detents serves to urge said print wheel precisely into the corresponding print position and hold it there regardless of any side play existing between said detents and their guide slots.

Claim 8

In a print wheel assembly comprising a frame member including a shaft, said frame member including guide slot means extending into the material of the frame member and opening at the exterior thereof, a print wheel rotatably disposed on said shaft for rotational movement to any one of a plurality of print positions, said print wheel including an annular serrated peripheral portion having a plurality of slope-faced teeth in line with said guide slot means, each of said teeth including a clockwise face and a counterclockwise face, and non-locking detent means slidably and loosely guided in said guide slot means, and spring urged towards said peripheral portion to cooperate with the teeth of said wheel to urge the wheel approximately into any selected print position, said non-locking detent means constituting the sole means for determining the static rotary position of said wheel, the improvement which comprises: said guide slot means comprising at least one pair of complementary guide slots, and said non-locking detent means comprising at least one pair of cooperating detents including a first detent and a second detent each guided in one of said complementary guide slots for movement towards and away from said peripheral portion, said detents each being spring urged for independent movement towards said peripheral portion, the position of said complementary guide slots being so arranged that when the print wheel is at rest approximately at one of said print positions, the first detEnt of said pair is spaced away from each of said counterclockwise faces and only engages one of said clockwise faces to exert a first positive torque on said print wheel in one direction, and the second detent of said pair is spaced away from each of said clockwise faces and only engages one of said counterclockwise faces for exerting a second positive torque on said print wheel substantially equal in magnitude but opposite in direction to said first torque, whereby the joint action of the detents serves to urge said print wheel precisely into the corresponding print position and hold it there regardless of any side play existing between said detents and their guide slots.