Dynamic information storage or retrieval – Dynamic mechanism subsystem – Having power driven transducer assembly
Reexamination Certificate
2000-06-08
2002-11-12
Cao, Allen (Department: 2652)
Dynamic information storage or retrieval
Dynamic mechanism subsystem
Having power driven transducer assembly
C369S015000
Reexamination Certificate
active
06480458
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for driving a movable body by means of a driving power source and a driving gear, and particularly to an apparatus for driving a pickup for an information recording and reproducing apparatus in the radius direction of a disc.
2. Description of the Related Art
There is known a conventional pickup driving apparatus, which has a driving motor
101
and a gear train
102
for transmitting driving power from the driving motor
101
to a pickup, as shown in FIG.
7
. The gear train
102
comprises, for example, a driving gear
104
having a central bore into which an output shaft
103
of the driving motor
101
is fitted forcibly; a reduction gear
105
engaging with the driving gear
104
; an intermediate gear
106
engaging with the reduction gear
105
; a small gear
107
formed integrally with the intermediate gear
106
; and a rack
108
engaging with the small gear
107
. The pickup is connected to the rack
108
and supported slidably on a guide shaft provided on a base. Drive of the driving motor
101
causes driving power to be transmitted sequentially to the respective gears
104
,
105
,
106
and
107
and the rack
108
. As a result, the pickup slides along the guide shaft so as to move in the radius direction of an optical disc;
Vibration and impact applied to a main body of the above-mentioned pickup driving apparatus causes an excessively large force to be applied to the gear train
102
. Even after the pickup moves at a single stroke from the central side of the disc toward the outer peripheral side thereof, or from the outer peripheral side thereof toward the central side thereof, to reach the limit position of the sliding range along the guide shaft, a shaft of the driving motor
101
may rotate due to the inertial force of the driving motor
101
itself, thus applying force having a function of further moving the pickup. In such a case, an excessively large force is applied to the gear train
102
. Application of such an excessively large force to the gear train
102
causes the teeth of the gear to be broken and a shaft for the gear to be deformed.
In order to prevent the occurrence of such a problem, the teeth of the rack
108
, which locate on the opposite sides, are formed into a deformed teeth
109
having a reduced height. When a prescribed load is applied to the engaging portions of the gear train
102
, the guide shaft for supporting the pickup and a boss for supporting the respective gear may deform to cause the tooth of the small gear
107
to jump over the deformed tooth
109
of the rack
108
(hereinafter referred to as the “tooth jump”) to make an engagement of the small gear
107
with the rack
108
. Stress applied onto the tooth flank may be released in this manner.
However, in the conventional pickup driving apparatus, it is necessary to form the deformed teeth on the opposite ends of the rack, thus requiring a high precision in formation of the rack.
In addition, an improperly long distance between the rack and the small gear causes the tooth jump easily, but a proper engagement of the small gear and the rack cannot be provided. On the contrary, an improperly short distance between them does not cause the tooth jump. Accordingly, a precise control is required in distance between the rack and the small gear, and an assembling step cannot be carried out easily. A frequent occurrence of the tooth jump between the small gear and the rack causes the deformed teeth to wear away, thus causing problems in durability. A reciprocal motion of the driving motor in a small stroke is required to recover the normal state from the tooth jumping state, thus requiring a relatively long period of time.
SUMMARY OF THE INVENTION
An object of the present invention is therefore to provide an apparatus for driving a movable body, which can prevent an excessively large force from being applied to the gear train, without forming deformed teeth on the opposite ends of the rack to which a the movable body such as a pickup is to be connected.
In accordance with the inventors' attention directed to the fact that the driving gear, having the central bore in which the output shaft of the driving power source is fitted forcibly, may slip to rotate relative to the output shaft when a torque applied to the driving gear exceeds a prescribed value, the prescribed torque value is determined so that the driving gear does not slip relative to the output shaft in case of the normal use condition of the driving apparatus, on the one hand, and that the driving gear slips relative to the output shaft in case of the overloaded condition of the driving gear, thus preventing an excessively large load from being applied to the gear train.
In order to attain the aforementioned object, an apparatus of the present invention for driving a movable body comprises:
a driving power source having an output shaft; and
a driving gear provided on said output shaft to drive said movable body,
wherein:
said driving gear is capable of slipping relative to said output shaft of said driving power source.
According to the apparatus of the present invention, the driving gear may slip relative to the output shaft, thus preventing an excessively large load from being applied to the engaging portions of the gear train. It is therefore possible to prevent the excessively large load from being applied to the gear train without forming deformed teeth on the opposite ends of the rack, which forms a part of the gear train. A normal working precision in formation of the rack suffices. There is not required a high precision arrangement to adjust the distance between the driving gear and the rack in the assembling step. Gears of the gear train always engage with each other, thus requiring no reciprocal motion of the driving power source in a small stroke to recover the normal state from the tooth jumping state. The driving operation of the movable body driving apparatus can be simplified, permitting to make a rapid operation.
In the above-mentioned apparatus of the present invention, there may be adopted a structure in which said output shaft of said driving power source is connected to said movable body through a gear train for transmitting driving power from said driving power source to said movable body, said gear train including said driving gear; and said driving gear slips when a prescribed load is applied to said gear train. In the present invention, the gear train includes a rack for moving linearly the movable body.
The prescribed torque by which the driving gear slips relative to the output shaft, is determined so that the driving gear does not slip relative to the output shaft in case of the normal use condition of the driving apparatus, on the one hand, and that the driving gear slips relative to the output shaft in case where stress, which may break the tooth flank of the gear train, is applied by vibration, impact and the like, on the other hand. The prescribed torque can be obtained by adjusting the fitting condition of the driving gear into the output shaft, or adjusting the fitting length of them, or selecting material for the output shaft and the driving gear.
According to the above-mentioned structure, when the prescribed load is applied to the gear train, the driving gear slips relative to the output shaft, thus preventing an excessively large load from being applied to the engaging portions of the gear train. It is therefore possible to prevent the excessively large load from being applied to the gear train without forming deformed teeth on the opposite ends of the rack, which forms a part of the gear train. Gears of the gear train always engage with each other, thus requiring no reciprocal motion of the driving power source in a small stroke to recover the normal state from the tooth jumping state. The driving operation of the movable body driving apparatus can be simplified, permitting to make a rapid operation.
The above-mentioned apparatus of the present invention may further comprise a stop
Konno Youichi
Muta Tsutomu
Cao Allen
Nguyen Dzung C.
Pioneer Corporation
Young & Thompson
LandOfFree
Apparatus for driving a movable body does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus for driving a movable body, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for driving a movable body will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2970668