Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – With rotor
Reexamination Certificate
2000-11-27
2003-03-25
Le, N. (Department: 2858)
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
With rotor
C324S537000, C324S758010
Reexamination Certificate
active
06538425
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of measuring a mounting accuracy of an electric-component mounting system which mounts at least one electric component (e.g., an electronic component) on a circuit substrate such as a printed wiring board, and particularly to the art of inspecting a plurality of portions of the mounting system that relate to its mounting accuracy.
2. Discussion of Related Art
Recently, there has been a strong demand to improve a mounting accuracy with which an electric-component (EC) mounting system mounts at least one electric component (EC) on a circuit substrate, so as to meet the need to decrease the distances between the lead wires of each EC and/or the need to increase the density of mounting of ECs. To this end, it has been practiced to detect at least one positional error of one of a plurality of portions of the EC mounting system that relate to its mounting accuracy, relative to the other portion or at least one of the other portions. Those portions include an EC holder which holds an EC, a first image taking device which takes an image of the EC held by the EC holder, and a second image taking device which takes an image of a reference mark of a circuit substrate on which the EC is to be mounted. Based on the detected positional error, the EC mounting system controls its EC mounting operation. In the conventional accuracy measuring method, a special measuring device is employed to measure the positional error on the EC mounting system, and the thus measured positional error is used to adjust the mounting system, when the system is manufactured or when the system is subjected to maintenance by user.
That is, the conventional accuracy measuring method needs the special measuring device to measure the positional error from the EC mounting system, and accordingly the user cannot easily measure the error.
Meanwhile, the positional error with the EC mounting system may change because of the deformation of the mounting system as a whole that is caused by the change of temperature of ambient air or by the increase of temperature resulting from the heat generation of one or more servomotors and/or the friction of one or more ball screws. The change of positional error may also be caused by the wearing and/or deformation of one or more parts of the mounting system. Thus, the improvement of mounting accuracy of the EC mounting system needs to measure frequently the positional error from the mounting system and adapt the system to the changes of the positional error. However, in the conventional accuracy measuring method and apparatus, a plurality of positional errors are measured in a plurality of measuring actions (ideally, several tens of measuring actions) in each one positional-error measuring operation, and an average of those errors is obtained to minimize the error of measurement. This means that it is difficult to perform frequently the positional-error measuring operations and adapt the mounting system to the changes of the positional error.
Moreover, in the conventional accuracy measuring method, a characteristic value of the EC mounting system that is obtained as a value relating to its mounting accuracy is treated as if it were constant. More specifically described, a plurality of characteristic values of the EC mounting system are measured in a plurality of measuring actions, and an average of those characteristic values is obtained as a proper characteristic value of the mounting system. However, the proper characteristic value of the mounting system that is obtained once is used as if it were constant till the next positional-error measuring operation is carried out to update the proper characteristic value. In fact, the proper characteristic value changes as the EC mmounting operation of the EC mounting system progresses or as the amount of operation of the mounting system increases.
SUMMARY OF THE INVENTION
The present invention provides an accuracy measuring method, an accuracy-measuring-program recording medium, and an electric-component mounting system which have one or more of the following technical features that are described below in respective paragraphs given parenthesized sequential numbers (1) to (25). 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 measuring an accuracy with which an electric-component mounting system mounts at least one electric component on a circuit substrate, the electric-component mounting system including at least one component holder for holding the at least one electric component, a substrate supporting device for supporting the circuit substrate, a first image-taking device for taking an image of at least a portion of the electric component held by the component holder, and a second image-taking device for taking an image of at least a portion of the circuit substrate supported by the substrate supporting device, at least two elements out of the component holder, the first image-taking device and the second image-taking device relating to the accuracy, the method comprising the step of measuring, with the electric-component mounting system, at least one positional error of one of the component holder, the first image-taking device and the second image-taking device relative to at least one of the others of the component holder and the first and second image-taking devices.
In the present accuracy measuring method, the mounting accuracy of the EC mounting system is measured with the mounting system itself. Thus, the mounting accuracy can be easily measured and accordingly can be measured frequently. That is, the deformation of the mounting system as a whole that is caused by the change of temperature of ambient air, the heat generation of one or more servomotors, the increase of temperature resulting from the friction of one or more ball screws, etc. can be detected frequently, which leads to improving the mounting accuracy of the mounting system. The first and second image-taking devices may be provided by a single image-taking device. The above-indicated at least one positional error may comprise at least one of (a) at least one positional error of an axis line of one of the component holder and the first and second image-taking devices relative to an axis line of at least one of the others of the component holder and the first and second image-taking devices (e.g., as seen in at least one of an X-axis direction and a Y-axis direction) and (b) a phase or angular error (i.e., a rotation-position error) of an axis line of one of the component holder and the first and second image-taking devices relative to an axis line of at least one of the others of the component holder and the first and second image-taking devices.
(2) According to a second feature of the present invention, there is provided a method of measuring an accuracy with which an electric-component mounting system mounts at least one electric component on a circuit substrate, the electric-component mounting system including at least one component holder for holding the at least one electric component, a substrate supporting device for supporting the circuit substrate, a first image-taking device for taking an image of at least a portion of the electric component held by the component holder, and a second image-taking device for taking an image of at least a portion of the circuit substrate supported by the substrate supporting device, at least two elem
Fuji Machine Mfg. Co. Ltd.
Le N.
Sundaram T. R
LandOfFree
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