Metal working – Means to assemble or disassemble – Means to assemble electrical device
Reexamination Certificate
2001-09-10
2004-05-25
Vo, Peter (Department: 3729)
Metal working
Means to assemble or disassemble
Means to assemble electrical device
C029S740000, C029S741000, C029S742000, C029SDIG004, C029S833000, C029S834000, C029S720000, C029S721000, C294S064200, C414S737000, C901S047000
Reexamination Certificate
active
06739036
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to a method of supplying a suction nozzle with electric components (including electronic components), and an electric-component mounting system arranged to mount the electric components on a circuit substrate such as a printed-wiring board, and more particularly to techniques for reducing a failure of the suction nozzle to hold the electric components by suction.
2. Discussion of Related Art
A suction nozzle is arranged to hold an electric component by suction under a reduced or negative pressure, and is used in an electric-component mounting system, for example. In the electric-component mounting system, the electric component is supplied from a component supply device, and is held by the suction nozzle, so that the electric component is mounted on a circuit substrate. The suction nozzle is arranged to receive the electric components from the component supply device, at a predetermined component receiving position, but may suffer from a sucking failure, that is, a failure to correctly hold the electric component by suction, such as a failure to receive the electric component.
The sucking failure takes place due to inadequate positioning of the electric component with respect to the suction nozzle upon sucking of the electric component by the suction nozzle, a positioning error of the component supply device and a positioning error of a component-holding head which holds the suction nozzle. An adequate sucking position of the electric component at which the electric component can be sucked by the suction nozzle with high stability changes with the specific shape and size of the electric component, and may deviate from the center position of the electric component. The inadequate positioning error of the electric component with respect to the suction nozzle may be caused when the component supply device and the suction nozzle are positioned relative to each other such that the electric component is always sucked at its central portion by the suction nozzle. The positioning errors of the component supply device and the component-holding head may be caused by manufacturing and assembling errors and local thermal expansion of the component supply device, the component-holding head and the related devices. In view of the above, it has been a conventional practice to determine the sucking position of the electric component depending upon the specific kind of the electric component, obtain the positioning errors of the component supply device and the component-holding head, and position the sucking surface of the suction nozzle and the component supply device relative to each other, on the basis of the determined sucking position and the obtained positioning errors, for thereby reducing the inadequate positioning of the electric component with respect to the suction nozzle.
However, the conventional practice still suffers from the sucking failure due to inadequate positioning of the electric component with respect to the sucking surface of the suction nozzle. Where the suction nozzle includes a suction pipe whose end face functions as the sucking surface, for example, a bending of the suction pipe causes a positional deviation of the sucking surface with respect to the electric component, resulting in the sucking failure, such as a failure to receive the electric component or inadequate holding of the electric component that cannot be corrected. Conventionally, bending of the suction pipe is detected to check whether the suction pipe if bent can be used for mounting the electric component, or whether the bent suction pipe should be replaced with a new one. This detection of the bending of the suction pipe is affected for the purpose of avoiding the use of the defective suction nozzle for mounting the electric component. However, the bending of the suction pipe is not conventionally taken into account when the electric component is sucked by the suction nozzle. This is one of the reasons for the sucking failure in the prior art.
SUMMARY OF THE INVENTION
The present invention was made in view of the problems encountered in the prior art described above. It is therefore an object of the present invention to reduce a failure of the suction nozzle to correctly hold the electric component by suction, in a method of transferring the electric component from the component supply device to the suction nozzle, and an electric-component mounting system arranged to mount the electric component on a substrate.
The above object may be achieved according to any one of the following modes of the present invention in the form of a method of supplying a suction nozzle with an electric component and an electric-component mounting system. Each of the following modes of the invention is numbered like the appended claims and depends from the other mode or modes, where appropriate, to indicate and clarify possible combinations of elements or technical features. It is to be understood that the present invention is not limited to the technical features or any combinations thereof which will be described for illustrative purpose only. It is to be further understood that a plurality of elements or features included in any one of the following modes of the invention are not necessarily provided all together, and that the invention may be embodied without some of the elements or features described with respect to the same mode.
(1) A method of controlling an operation in which electric components are transferred one after another from a component supply device to a suction nozzle which is held by a component-holding head rotatable about an axis of rotation thereof, such that the suction nozzle extends in an axial direction of the component-holding head, each of the electric components being held by the suction nozzle by suction on a sucking surface provided at a free end of the suction nozzle, the method comprising:
a relative-position obtaining step of obtaining a relative position between the sucking surface and the axis of rotation of the component-holding head;
a relative-movement step of effecting a relative movement between the component-holding head and the component supply device on the basis of the relative position obtained in the relative-position obtaining step, so as to minimize an error of relative positioning between the sucking surface and a predetermined sucking position of the electric component positioned at the component-supply portion; and
a component supply step of moving, after the relative movement between the component-holding head and the component supply device in the relative-movement step, the component-holding head and the component supply device toward each other, for transferring one of the electronic components from the component supply device to said suction nozzle.
In the absence of a positioning error of the sucking surface with respect to the axis of the component-holding head (hereinafter referred to simply as “head axis”), there is established a predetermined relative position between the predetermined sucking position of the electric component and the head axis, so that there is established a predetermined relative position between the sucking surface and the predetermined sucking position, when the electric component (typically, an electronic component) is transferred from the component-supply portion to the suction nozzle. In the presence of a positioning error of the sucking surface with respect to the head axis, on the other hand, there exists a positioning error between the sucking surface and the predetermined sucking position of the electric component positioned at the component-supply portion. This positioning error between the sucking surface and the predetermined sucking position corresponds to the positioning error between the sucking surface and the head axis. Where the angular position of the component-holding head in which the relative position between the sucking surface and the head axis is obtained is the same as the angular position in which the electric compone
Ito Toshiya
Koike Hirokazu
Suhara Shinsuke
Fuji Machine Mfg. Co. Ltd.
Oliff & Berridg,e PLC
Trinh Minh
Vo Peter
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