Image analysis – Applications – Manufacturing or product inspection
Reexamination Certificate
2000-12-26
2004-09-07
Werner, Brian (Department: 2621)
Image analysis
Applications
Manufacturing or product inspection
C382S151000
Reexamination Certificate
active
06788806
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of inspecting whether a printed board is appropriately supported in an electric-component mounting apparatus.
2. Discussion of Related Art
There is known an electric-component (EC) mounting apparatus which takes, with an image taking device, an image of a reference mark provided on a printed board (e.g., printed wiring board) which is supported by a supporting device, determines, based on the taken image of the reference mark, a position of the printed board supported by the supporting device, and modifies a prescribed amount of movement of an EC that is needed to position the EC at a position right above an EC-mount location on the printed board. However, the conventional apparatus determines, on the assumption that the printed board is appropriately supported by the supporting device, a positional error of the printed board from a prescribed position thereof, and modifies, based on the determined positional error of the printed board, the prescribed amount of movement of EC that is needed to position the EC at the position right above the EC-mount location on the printed board and mount the EC at the EC-mount location.
Therefore, even in the case where the magnitude of actual positional error of the printed board exceeds a permissible error range which is proper for the supporting device and/or the image taking device, the conventional apparatus may mount one or more ECs on the printed board. In addition, in the case where the actual positional error of printed board is great, a great error or errors tend to occur when the positional error is determined or calculated and/or when the positional error is corrected. More specifically described, if the actual position of the printed board is greatly deviated from the prescribed position thereof, then the image of the reference mark that should be taken around the center of view field of the image taking device is, in fact, taken in a peripheral portion of the view field. However, generally, the image taking device (e.g., camera) tends to have a greater distortion in the peripheral portion of view field (e.g., lens) thereof. Therefore, a greater error tends to occur when the positional error of the printed board is calculated based on the reference-mark image taken by the image taking device. Moreover, if the prescribed amount of movement of EC is greatly modified based on the great positional error of printed board, a great error tends to be included in the modified amount of movement of EC, so that the EC may be mounted, with insufficient accuracy, on the printed board (e.g., printed circuit board).
In addition, if the magnitude of actual positional error of the printed board exceeds the above-indicated permissible error range, then abnormality may have occurred to the EC mounting apparatus itself, or the printed board currently supported by the supporting device may differ from the prescribed sort of printed board. The abnormality with the EC mounting apparatus itself may be such that a board conveyor (i.e., a pair of conveyor belts) has failed to adjust appropriately its board-convey width depending upon the size of current sort of printed boards and accordingly the printed board has been conveyed in an unstable state, or such that the overall shape of the printed board has been deformed because the relative position between the printed board and the supporting device in a vertical direction is not appropriate.
FIGS. 6A
,
6
B, and
6
C show a case where an EC
206
is mounted on a second, upper surface
204
of a printed board
200
having, in addition to the second surface
204
, a first, lower surface
202
having an EC
206
already mounted thereon. A board supporting device
208
includes at least one board support member
209
, and is moved upward from its initial position shown in
FIG. 6A
, so that the board support member
209
engages the first surface
202
of the printed board
200
, as shown in
FIG. 6C
, and thereby supports the board
200
. In this case, the conventional EC mounting apparatus may suffer from the above-described problems. If an actual position of the printed board
200
is largely deviated from its prescribed position, the board support member
209
interferes with the EC
206
already mounted on the first surface
202
, as shown in FIG.
6
B. Consequently the EC
206
mounted on the first surface
202
is removed from the surface
202
, as shown in
FIG. 6C
, or is moved out of position or changed in its posture on the surface
202
, because it has been just temporarily fixed to the surface
202
with creamed solder or adhesive. Even if the EC
206
may be mounted on the second surface
204
of the printed board
200
whose first surface
202
has had the above-indicated abnormality, the printed board
200
will be discarded as a defective product. Therefore, the one or more ECs
206
mounted on the second surface
204
and the time needed to mount the ECs
206
on the second surface
204
are used to waste.
When the EC
206
already mounted on the first surface
202
is interfered with by the board support member
209
, the EC
206
may not be removed off the first surface
202
or be moved out of position. In this case, however, the printed board
200
is supported by the board supporting device
208
in the state in which the EC
206
is sandwiched between the board
200
and the support member
209
, so that the board
200
is pushed up by the EC
206
and its shape is deformed. In this state, it is difficult to mount appropriately the EC or ECs
206
on the second surface
204
of the board
200
. Eventually, the board
200
will probably be defective. These problems have been more and more serious because of a recent demand to increase the density of mounting of ECs.
SUMMARY OF THE INVENTION
The present invention provides a board-supporting inspecting method, an electric-component mounting apparatus, and an inspecting-program recording medium which have one or more of the following technical features that are described below in respective paragraphs given parenthesized sequential numbers (1) to (16). 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. 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.
(1) According to a first feature of the present invention, there is provided a method of inspecting whether a printed board is appropriately supported by a supporting device, when a holding device holding an electric component mounts the electric component on the printed board supported by the supporting device, the method comprising the steps of taking, with an image taking device, an image of at least one prescribed detection portion of the printed board supported by the supporting device, and judging, based on image data representing the taken image of the detection portion, whether the printed board is appropriately supported by the supporting device. The image taking device can be regarded as a sort of detecting device which detects the prescribed or predetermined detection portion of the printed board.
In a conventional EC mounting method, a relative position of the printed board relative to the EC holding device is determined based on a relative position of a reference mark, as a sort of prescribed detection portion of the printed board, relative to the image taking device, and an amount of relative movement between the EC holding device and the board supporting device is modified based on the determined position of the printed board, so that the EC held by the holding device is accurately mounted
Kadomatsu Sumio
Kawai Takayoshi
Fuji Machine Manufacturing Company
Oliff & Berridg,e PLC
Werner Brian
LandOfFree
Board-supporting inspecting method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Board-supporting inspecting method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Board-supporting inspecting method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3260776