Work holders – With fluid means – Vacuum-type holding means
Reexamination Certificate
2001-07-27
2003-07-01
Miller, Carl S. (Department: 3747)
Work holders
With fluid means
Vacuum-type holding means
C029S744000, C269S008000, C269S903000
Reexamination Certificate
active
06585245
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a system for performing an operation relating to a printed wiring board (PWB) and particularly to the art of supporting a PWB. A PWB with electric components (e.g., electronic components) being mounted thereon should be called as a printed circuit board (PCB) but, in the present specification, a PCB is also referred to as a PWB, for avoiding complexity.
2. Discussion of Related Art
Generally, a PWB includes a thin substrate formed of an electrically insulating material such as a synthetic resin, and a circuit pattern formed of an electrically conductive material on the thin substrate. Thus, the PWB has flexibility. Therefore, when electric components (ECs) are mounted on the PWB, or when an adhesive or a creamed solder is applied to the PWB before the mounting of ECs, the PWB cannot maintain an accurate planeness or flatness, unless a back surface of the PWB is supported at a considerably large number of points.
To solve this problem, Japanese Patent Document No. 7-15189 teaches using supporting pins to support a back surface of a PWB. More specifically described, this document discloses a PWB supporting device including a base plate and a plurality of supporting pins. Each of the supporting pins has, at one of lengthwise opposite ends thereof, a support surface to support a PWB, and the other end portion of the each pin is formed of a permanent magnet. Thus, each supporting pin can be fixed owing to a magnetic force to the base plate that is formed of a magnetic material.
The supporting pins support the back surface of the PWB. However, the supporting pins must not engage uneven portions of the PWB itself or the ECs already mounted on the back surface thereof. Therefore, the supporting pins must engage only limited portions of the back surface of the PWB. Generally, different sorts of PWB have different patterns of limited portions that can be engaged by the supporting pins. Therefore, when the current sort of PWBs for each of which an operation is to be performed are changed to a new sort of PWBs, the supporting pins are re-arranged on the base plate. In the case where the supporting pins are automatically re-arranged, a force that can overcome the magnetic force being exerted on each supporting pin is applied to the each pin in a direction away from the base plate, so as to detach the each pin from the base plate. Subsequently, supporting pins that are to support the new sort of PWBs are attached to the base plate.
When each supporting pin is detached from the base plate, the each pin, however, is not detached before the force applied to the each pin overcomes the magnetic force. Once the force applied to the each pin overcomes the magnetic force, the magnetic force abruptly decreases as the each pin is moved away from the base plate. Thus, an impact occurs to the base plate, so that the base plate is vibrated and an impact sound is produced. If a smaller magnetic force is exerted to the each pin, a smaller impact will occur. However, the smaller magnetic force may be too weak to fix the each pin to the base plate.
SUMMARY OF THE INVENTION
The present invention provides a PWB-relating-operation performing system that has each feature described below. The following features are described, like claims, in respective paragraphs that are given respective sequential numbers. Any feature that includes another feature shall do so by referring to the number given to the latter feature. However, the following features and the appropriate combinations thereof are just examples to which the technical features, and the combinations thereof, described in the specification are by no means limited. In addition, in the case where one feature recites a plurality of items, it is not essentially required that all of those items be simultaneously employed in the one feature. That is, it is possible to select and employ only a portion (one, two, . . . , but not all) of those items.
(1) According to a first feature of the present invention, there is provided a system for performing an operation relating a printed wiring board, comprising a first supporting table which has a planar first supporting surface, at least a portion of the first supporting table that defines the first supporting surface being formed of a ferromagnetic material; a plurality of supporting members each of which has a seat portion having a bottom surface which is seated on the first supporting surface, and a support surface which is opposite to the bottom surface, at least a portion of the seat portion being formed of a permanent magnet, the each supporting member being attached, owing to a magnetic force of the permanent magnet, to the first supporting surface to support a back surface of the printed wiring board; an operation performing device which performs an operation for a front surface of the printed wiring board whose back surface is supported by the respective support surfaces of the supporting members; a second supporting table which is provided in a vicinity of the first supporting table and has a second supporting surface which is substantially continuous with the first supporting surface on a common plane, at least a portion of the second supporting table that defines the second supporting surface being formed of a ferromagnetic material; and a supporting-member moving device which moves the each supporting member from the second supporting surface to the first supporting surface, and from the first supporting surface to the second supporting surface, by sliding the each supporting member on the first and second supporting surfaces.
Each of the supporting members may be either a holding member, recited in the fifth feature (5), that supports the printed wiring board (PWB) while applying negative pressure to the board and thereby holding the same, or a simple member which just supports the PWB and does not have the holding function.
The operation performing device may be an electric-component mounting device which mounts electric components (ECs) on a front surface of PWB; a screen printing machine which screen-prints creamed solder on a front surface of a PWB; a highly-viscous-fluid applying device which sequentially applies a highly viscous fluid, such as adhesive, to a single spot, or plural spots, on a front surface of each of PWBs; or an electric-circuit inspecting device which inspects an electric circuit formed on a front surface of a PWB.
The first and second supporting surfaces may be always kept substantially continuous with each other on the common plane, or may be temporarily made substantially continuous with each other on the common plane. In the former case, the first and second supporting surfaces may be provided by a single continuous planar surface, or two planar surfaces which are independent of each other and are contiguous with each other without a gap or a step therebetween or adjacent to each other with a small gap or step therebetween. The phrase “substantially continuous” used in this feature means that the first and second supporting surfaces do not have a gap or step therebetween, or have such gap and/or step which allow each supporting member to slide and move between the two supporting surfaces. More specifically described, the first and second supporting surfaces may have a step having such a dimension which assures that, owing to a roundness or a chamfer which is present at an edge of the bottom surface or the support surface of each supporting member and has the function of guiding the each supporting member, the each supporting member can be moved over the step; and/or a gap having such a dimension which is sufficiently smaller than that of the bottom surface of each supporting member and assures that in a state in which one of the first and second supporting surfaces is stably supporting the bottom surface of the each supporting member, the other supporting surface starts supporting a portion of the bottom surface. In the case where the first and second supporting surfaces are temporarily mad
Isogai Takeyoshi
Iwaki Noriaki
Katsumi Hiroshi
Fuji Machine Manufacturing Co., Ltd.
Miller Carl S.
Oliff & Berridg,e PLC
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