Machine element or mechanism – Gearing – Directly cooperating gears
Patent
1992-08-19
1994-09-13
Braun, Leslie A.
Machine element or mechanism
Gearing
Directly cooperating gears
74425, 74606R, F16H 112, F16H 5702
Patent
active
053458346
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a velocity-reduced drive system, and more particularly to a small or flat velocity-reduced drive system for operating a small device like a video camera or a combined camera-and-video-tape-recorder unit by reducing the velocity of a motor.
2. Description of the Related Art
It is necessary to reduce the velocity of a motor for a lens driving unit when such unit is operated for focusing or zooming a video camera or a combined camera-and-video-tape-recorder unit (hereinafter called camera-and-VTR unit). One of such velocity-reduced drive systems was proposed in Japanese Patent Laid-Open Publication No. 74342/1989. With the cited system, the velocity of the motor is reduced by a reduction gear train or by combination of the reduction gear train and a pulley-belt unit. A drive shaft of the motor and an output shaft are positioned in the same direction.
Conventionally, the motor and a case for the reduction gear unit are piled with the drive shaft and the output shaft facing in the same direction. Therefore, the drive shaft inevitably becomes longer. The reduction gear train includes a plurality of spur gears, which generate relatively high sounds. Such high sounds are picked up by a microphone of the video camera, being reproduced as noises. Since the direction of the output shaft is limited, the velocity-reduced drive system would have narrower application fields. Further, a number of the spur gears have to be used to obtain large velocity reductions, which means increase of component parts.
When the velocity-reduced drive system is used to operate a cylindrical movable member (e.g. a lens barrel of a combined camera-and-VTR unit), there would be formed an undesired space around the flat surface of the drive system and the cylindrical member.
SUMMARY OF THE INVENTION
It is therefore an object of this invention to provide a velocity-reduced drive system which is compact, being able to obtain large velocity reductions, and to suppress noises.
A further object of the invention is to provide a velocity-reduced drive system which is suitable for operating a movable member of a video camera or a combined camera-and-VTR unit.
A still further object of the invention is to provide a velocity-reduced drive system which is suitable to operate a cylindrical movable member, being compact to save a useless space between the drive system and the cylindrical movable member.
According to the invention, there is provided a velocity-reduced drive system comprising: a micro or flat motor for producing a relatively large torque and mounted in a case, and a reduction gear unit. The reduction gear unit includes a worm gear, a first power transmission means for transmitting rotational force of the motor to the worm gear, a worm wheel meshed with the worm gear, and a second power transmission means for transmitting rotational force of the worm gear to an output shaft.
The output shaft has a coupling member via which it is coupled to a movable member to be operated at a reduced velocity.
When the drive system is applied to a movable member such a lens barrel of a video camera, the drive shaft of the motor is positioned in parallel with the worm gear. With respect to a plane formed by the first power transmission means, the motor is remote from the movable member, and a reduction gear unit is near the movable member. Further, the motor and the reduction gear unit are arranged along an imaginary circumference whose center agrees with the movable member.
Rotational force of the motor is reduced its velocity while it is being transmitted to a destination, i.e. the movable member, via the first power transmission means, worm gear, worm wheel, second power transmission means, and output shaft.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view of a velocity-reduced drive system according to a first embodiment of the invention, taken along line 1--1 of FIG. 2;
FIG. 2 is a front view of the velocity-reduced drive system of FIG. 1;
FIG. 3 is a
REFERENCES:
patent: 2225957 (1940-12-01), Korff
patent: 2974409 (1961-03-01), Ghinazzi
patent: 4026163 (1977-05-01), Merkert
patent: 4686863 (1987-08-01), Inoue et al.
patent: 5128770 (1992-07-01), Iaana et al.
Abart Gear & Machine Co., pp. 2, 3, and 10-21, 1924.
Braun Leslie A.
Kabushiki Kaisha Sankyo Seiki Seisakusho
Laub David W.
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