| 摘要 |
Apparatus for selectively imparting rotary motion to two spaced apart rotary members which may be used in a web or tape transport mechanism to bi-directionally transport a web or tape. In a preferred embodiment, this apparatus is used as a tape transport in a magnetic recording and/or playback machine. A drive roll in the tape transport mechanism selectively contacts one of the rotary members. The drive roll is coupled to a bi-directional drive motor and includes an extending shaft segment. A string member, tensioned at each end, has an intermediate portion thereof deployed about the extending shaft segment of the drive roll. Upon rotation of the drive motor in one direction, the drive roll and shaft segment rotate and the frictional forces between the string member and the shaft segment cause the shaft segment to traverse the string in a corresponding direction so as to bring the drive roll into contact with one of the rotary members. When the drive motor is reversed, the shaft segment rotates in the opposite direction causing the drive roll and extending shaft segment to traverse the string in the opposite direction to urge the drive roll into contact with the other rotary member. |
