Conveyors: power-driven – Conveyor section – Load simultaneously engaged between and moved by a plurality...
Reexamination Certificate
2000-07-03
2002-03-12
Schwartz, Christopher P. (Department: 3613)
Conveyors: power-driven
Conveyor section
Load simultaneously engaged between and moved by a plurality...
C198S465300, C198S817000
Reexamination Certificate
active
06354430
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a printed-wiring-board conveying method and a printed-wiring-board conveyor and particularly to the improvements of such a printed-wiring-board conveying method and a printed-wiring-board conveyor each of which employs a wound-on member, such as a belt, for conveying a printed wiring board.
2. Related Art Statement
There is known a printed-wiring-board (“PWB”) conveyor which includes an endless, annular conveyor belt, a plurality of pulleys on which the conveyor belt is wound, and a drive device which drives or rotates at least one of the pulleys. The conveyor belt includes a straightly and horizontally extending portion which directly supports a lower surface of a PWB. When one pulley is rotated by the drive device and accordingly the conveyor belt is moved, the PWB is conveyed by a frictional force produced between the PWB and the conveyor belt.
However, the above-indicated PWB conveyor has some problems. For example, the speed at which the PWB is conveyed has an upper limit, and accordingly it is difficult to improve the efficiency of conveying of PWBs. Though the PWB is conveyed by the frictional force produced between the PCB and the conveyor belt, as indicated above, the frictional force depends on the weight of the PWB and the coefficient of friction between the PWB and the conveyor belt. Therefore, the PWB cannot be conveyed at an acceleration greater than a maximum or upper-limit acceleration depending on gravitational acceleration.
In addition, since the above-indicated PWB conveyor conveys the PWB while supporting the lower surface thereof, many elements of the PWB conveyor are provided under the PWB, so that little free space is left under the PWB. Thus, it is not easy to provide another or other devices under the PWB. In addition, the PWB conveyor cannot help having a great vertical dimension. Thus, the conventional PWB conveyor suffers from a low degree of freedom.
SUMMARY OF THE INVENTION
The present invention provides a printed-wiring-board conveying method and a printed-wiring-board conveyor that have one or more of the following technical features that are described below in respective paragraphs given parenthesized sequential numbers (1) to (18). Any technical feature that includes another technical feature shall do so by referring, at the beginning, to the parenthesized sequential number given to the latter feature. Thus, two or more of the following technical features may be combined, if appropriate. Each technical feature may be accompanied by a supplemental explanation, as needed. However, the following technical features and the appropriate combinations thereof are just examples to which the present invention is by no means limited. In addition, in the case where one technical feature recites a plurality of items, it is not essentially required that all of those items be simultaneously employed. That is, it is possible to select and employ only a portion (one, two, . . . , but not all) of those items of that technical feature.
(1) According to a first feature of the present invention, there is provided a method of causing a wound-on member to contact a printed wiring board and conveying the printed wiring board by utilizing a frictional force produced between the wound-on member and the printed wiring board, the method comprising the steps of providing two conveying units each of which includes a wound-on member and two rotatable wheels on which the wound-on member is wound to have a straightly extending portion which straightly extends between the two rotatable wheels, such that the two conveying units are spaced from each other in a direction parallel to a printed wiring board, and such that the respective straightly extending portions of the two wound-on members of the two conveying units cooperate with each other to sandwich the printed wiring board in a direction substantially parallel to the printed wiring board, and conveying the printed wiring board by rotating the rotatable wheels of the two conveying units, and thereby moving the two wound-on members, while utilizing a frictional force produced between each of the two wound-on members and the printed wiring board. The printed wiring board may be one on which electric components (“ECs”) have been mounted and electrically connected to electric circuits, or one on which no electric components have been mounted. At least one of the rotatable wheels may be driven by a drive device, and this rotatable wheel will be referred to as the “drive rotatable wheel”. Since the printed wiring board (“PWB”) is conveyed while being sandwiched by the two conveying units in the direction substantially parallel to the upper and lower major surfaces of the PWB, the two conveying units can be provided on both sides of the PWB and accordingly a large space can be left under the PWB. In addition, the two conveying units can be easily constructed so as to be generally flat as seen in the direction parallel to the PWB. Moreover, in the case where the two wound-on members contact the PWB with a contact force greater than the weight of the PWB, the two wound-on members can move the PWB at an acceleration higher than a maximum acceleration that can be achieved depending on gravitational acceleration. The last advantage contributes to increasing the speed at which the PWB is conveyed and thereby improving the efficiency of conveying of PWBs. The present PWB conveying method may employ at least one of the second to eighteenth features (2) to (18) of the PWB conveyor, described below.
(2) According to a second feature of the present invention, there is provided a printed-wiring-board conveyor, comprising at least one wound-on member; at least two rotatable wheels on which the wound-on member is wound to have a straightly extending portion which straightly extends between the two rotatable wheels and which contacts a printed wiring board; a drive device which drives at least one of the two rotatable wheels and moves the wound-on member while utilizing a frictional force produced between the wound-on member and the printed wiring board; and a contact-force producing device which causes the straightly extending portion of the wound-on member and the printed wiring board to contact each other with a contact force greater than a weight of the printed wiring board. The wound-on member may be a belt such as a V-belt, a round belt, a flat belt, or a cog belt (i.e., a timing belt); a wire; or a chain. The rotatable wheels may be pulleys such as V-pulleys or flat pulleys; or sprockets, and can be selected corresponding to the sort of the wound-on member employed. The rotatable wheels may be ones which are rotatable about respective axis lines intersecting a reference plane parallel to the PWB, or about respective axis lines parallel to the reference plane. In the former case, the respective axis lines of the rotatable wheels may be perpendicular to the reference plane and, in this case, the wound-on member is circulated on a plane parallel to the reference plane; and in the latter case, the wound-on member is circulated on a plane perpendicular to the reference plane. However, depending upon the circumstances, the rotatable wheels may be rotated, as needed, about respective axis lines whose directions differ from each other, so that the wound-on member is circulated on a curved surface. The PWB may be conveyed in a horizontal direction, or in a direction inclined relative to a horizontal direction. The present PWB conveyor may employ two conveying units according to the third feature (3), at least three conveying units according to the fifteenth feature (15), or at least one conveying unit according to the seventeenth feature (17). In the third feature (3), the two conveying units convey the PWB while sandwiching the PWB in a direction substantially parallel to the above-indicated reference plane. In the fifteenth feature (15), two conveying units convey the PWB while sandwiching the PWB in a direction substantially parallel to the reference plane, and
Fuji Machine Mfg. Ltd.
Kramer Devon
Oliff & Berridg,e PLC
Schwartz Christopher P.
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