Camera device and drive mechanism
View Patent ↗A drive mechanism ( 1 ) of a camera apparatus includes a worm gear ( 4 ) to which a rotational driving force of a drive motor ( 2 ) is transmitted, a worm wheel ( 6 ) around which a helical gear ( 5 ) is formed to engage with the worm gear ( 4 ), and a support frame ( 7 ) which supports the worm wheel ( 6 ) rotatably and movably along a rotation axis. A rotational driving force of the worm gear ( 4 ) is transmitted to the worm wheel ( 6 ) with reduced gear ratio. An externally threaded portion ( 10 ) of a shaft portion ( 8 ) of the worm wheel ( 6 ) is engaged with an internally threaded portion in a supporting hole ( 14 ) of the support frame ( 7 ), so that the shaft portion ( 8 ) moves along the rotation axis when the worm wheel ( 6 ) rotates. Consequently, the rotational driving force transmitted to the worm wheel ( 6 ) is converted into a linear thrust force along the rotation axis. This makes it possible to provide a camera apparatus which can develop a larger thrust force and adjust an amount of travel more finely.
1. A camera apparatus comprising a drive mechanism which converts a rotational driving force of a drive source into a linear thrust force, wherein the camera apparatus comprises:
a drive gear to which the rotational driving force of the drive source is transmitted;
a driven member around which a helical gear is formed to engage with the drive gear and to which a rotational driving force of the drive gear is transmitted with reduced gear ratio;
a support unit which supports the driven member rotatably around a rotation axis of the driven member and movably along the rotation axis; and
a conversion unit which converts the rotational driving force transmitted to the driven member into a linear thrust force along the rotation axis so that the driven member moves along the rotation axis as the driven member rotates,
wherein the conversion unit comprises:
a first threaded portion which is provided with the driven member; and
a second threaded portion which is provided with the support unit and is engaged with the first threaded portion.
2. The camera apparatus according to claim 1 , wherein a thread direction of the first threaded portion with respect to the second threaded portion is set such that a direction of an auxiliary thrust force along the rotation axis matches a direction of the linear thrust force along the rotation axis, the auxiliary thrust force being received by the driven member from the drive gear via the helical gear when the rotational driving force is transmitted to the driven member from the drive gear, and the linear thrust force resulting from the conversion performed by the conversion unit when the driven member rotates.
3. The camera apparatus according to claim 1 , wherein the helical gear of the driven member has a gear width corresponding to an amount of travel of the driven member along the rotation axis, and a shaft portion which is a supported unit of the driven member has a shaft length corresponding to the amount of travel of the driven member along the rotation axis.
4. A drive mechanism which is mounted on a camera apparatus and converts a rotational driving force of a drive source into a linear thrust force, wherein the drive mechanism comprises:
a drive gear to which the rotational driving force of the drive source is transmitted;
a driven member around which a helical gear is formed to engage with the drive gear and to which a rotational driving force of the drive gear is transmitted with reduced gear ratio;
a support unit which supports the driven member rotatably around a rotation axis of the driven member and movably along the rotation axis; and
a conversion unit which converts the rotational driving force transmitted to the driven member into a linear thrust force along the rotation axis so that the driven member moves along the rotation axis as the driven member rotates,
wherein the conversion unit comprises:
a first threaded portion which is provided with the driven member; and
a second threaded portion which is provided with the support unit and is engaged with the first threaded portion.