Material or article handling – Elevator or hoist and loading or unloading means therefor – Automatic stop
Reexamination Certificate
2001-02-01
2002-12-31
Bratlie, Steven A. (Department: 3652)
Material or article handling
Elevator or hoist and loading or unloading means therefor
Automatic stop
C187S362000, C187S363000, C432S241000
Reexamination Certificate
active
06499933
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to a carrier conveying apparatus which is suitable for conveying carriers or the like in which, for example, substrates to be processed are accommodated and also relates to an elevating mechanism installed in the carrier conveying apparatus. In addition, the invention relates to a heat treatment installation.
2. Description of the Related Art
In general, a production process of semiconductor devices includes various steps of applying an oxidation process, diffusion process and CVD process etc. on semiconductor wafers as objects to be processed. Thus, in view of the improvement of throughput, cleanness and space-conserving etc. of these steps, a variety of processing apparatuses have been proposed [e.g. see Japanese Unexamined Patent Publication (Kokai) No. 4-133422].
For example, the processing apparatus disclosed in the above publication includes a vertical heat treatment furnace arranged on a rear and upper side inside a casing of the apparatus, for heat-treating a great number of wafers at a time, using a wafer boat as a carrier for objects to be processed. On the front side of the casing, a carrier input/output port (also called an I/O port) is provided for inputting and outputting a carrier as a container for accommodating a plurality of wafers therein.
Inside the above-mentioned casing, there are provided a carrier keeping section which is positioned on an upper side of the casing close to the carrier I/O port, for keeping a plurality of carriers; a carrier set-up section and a wafer boat set-up section both of which are arranged between the carrier I/O port and the heat treatment furnace, for delivering the wafers between the carrier and the wafer boat; and a wafer conveying mechanism for delivering the wafers between the carrier set-up section and the wafer boat set-up section. Further arranged in the casing is a carrier conveying apparatus with an elevating mechanism, which carries out the delivery of carriers between the carrier I/O port and the carrier keeping section, between the carrier keeping section and the carrier set-up section or between the carrier I/O port and the carrier set-up section.
Since it is necessary that, in the carrier conveying apparatus, the elevating mechanism has a relatively large stroke of e.g. 3 m to 5 m and the difficulty that the elevating mechanism employs a ball screw, a mechanism to elevate an elevating mechanism suspended by a wire or a timing belt as a suspension member is adopted as the elevating mechanism. Despite high strength in the suspension member, it is expected that if the suspension member is broken off, then utensils might be damaged because of the drop of such a heavy elevating mechanism weighing 70 to 80 kg, for example. Therefore, the above elevating mechanism is so constructed that, when a sensor detects the cutting of the suspension member, the elevating mechanism is stopped by a brake mechanism, thereby preventing the mechanism from falling.
In the above-mentioned elevating mechanism, however, it is necessary to provide a sensor for detecting the cutting of the suspension member and a control unit with electric circuits for controlling the brake mechanism by inputting a signal from the sensor etc. Therefore, with the increase in manufacturing cost and necessity of using electricity, there is a possibility that the elevating mechanism will have a faulty operation due to misidentification by the sensor.
SUMMARY OF THE INVENTION
Accordingly, it is therefore an object of the present invention to provide an elevating mechanism which is capable of mechanically stopping an elevating mechanism, not electrically, when the suspension member is broken off, whereby the elevating mechanism can be prevented from falling and to also provide a carrier conveying apparatus having the elevating mechanism.
According to the first feature of the invention, there is a provided an elevating mechanism comprising:
a guide member arranged along a vertical direction;
a fixed surface arranged in parallel with the guide member;
an elevating mechanism guided so as to rise and fall along the guide member;
a braking mechanism pivotally supported by the elevating mechanism in a vertical plane, the braking mechanism being in a position apart from the fixed surface under a normal condition of the braking mechanism and being rotated in a direction approaching the fixed surface from an underside of the elevating mechanism when the elevating mechanism falls, whereby the braking mechanism is engaged with the fixed surface to brake the elevating mechanism;
urging means for urging the braking mechanism to rotate in the direction approaching the fixed surface from the underside of the elevating mechanism;
a suspension member connected to the braking mechanism, for suspending the elevating mechanism through an intermediary of the braking mechanism, the suspension member, owing to its tensile strength to suspend the elevating mechanism, also rotationally urging the braking mechanism in a direction to separate the braking mechanism from the fixed surface in opposition to the rotating force due to the urging means; and
a stopper for stopping the rotation of the braking mechanism due to the tensile strength of the suspension member;
said stopper including:
a stopper member fixed to said braking mechanism, said stopper member having a stopper surface; and
an abutment member fixed to said elevating mechanism, said abutment member having an abutment surface;
whereby, said stopper stops the rotation of said braking mechanism due to the tensile strength of said suspension member by engaging said abutment surface with said stopper surface of said stopper member:
whereby, when the suspension member is cut off, the braking mechanism to which urging force due to the tensile strength of the suspension member is not applied any longer is rotated against the fixed surface by the urging means, so that the elevating mechanism can be braked.
According to this feature, when the suspension member is cut off, it is possible to stop the elevating mechanism mechanically, and not electrically, so that the elevating mechanism can be prevented from falling.
The second feature of the invention resides in a carrier conveying apparatus comprising:
a fixed frame arranged so as to extend in a vertical direction;
a supporting arm adapted so as to move in the vertical direction along the fixed frame, for conveying a carrier having an object to be processed accommodated therein; and
an elevating mechanism arranged between the fixed frame and the supporting arm, for moving the supporting arm to a predetermined position in the vertical direction and maintaining the supporting arm thereat so as not to fall down, the elevating mechanism including:
a guide member arranged on the fixed frame along a vertical direction;
a fixed surface arranged in parallel with the guide member;
an elevating mechanism guided so as to rise and fall along the guide member, for supporting the supporting arm;
a braking mechanism pivotally supported by the elevating mechanism in a vertical plane, the braking mechanism being in a position apart from the fixed surface under a normal condition of the braking mechanism and being rotated in a direction approaching the fixed surface from an underside of the elevating mechanism when the elevating mechanism falls, whereby the braking mechanism is engaged with the fixed surface to brake the elevating mechanism;
urging means for urging the braking mechanism so as to rotate in the direction approaching the fixed surface from the underside of the elevating mechanism;
a suspension member connected to the braking mechanism, for suspending the elevating mechanism through an intermediary of the braking mechanism, the suspension member, owing to its tensile strength to suspend the elevating mechanism, also rotationally urging the braking mechanism in a direction to separate the braking mechanism from the fixed surface in opposition to rotating force due to the urging means; and
a stop
Bratlie Steven A.
Smith , Gambrell & Russell, LLP
Tokyo Electron Limited
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