Image analysis – Applications – Manufacturing or product inspection
Reexamination Certificate
1996-11-15
2001-02-27
Mehta, Bhavesh (Department: 2721)
Image analysis
Applications
Manufacturing or product inspection
C382S149000, C348S125000
Reexamination Certificate
active
06195454
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a component mounting apparatus which mounts a component to a target position, and more particularly to a component mounting apparatus comprising a camera which detects a position of a component and a target mounting position.
2. Related Art
A component mounting apparatus mounts a component such as a TCP (Tape Carrier Package) on a printed circuit board to be attached into a personal computer, by using a robot. In such an apparatus, a single camera fixed to the apparatus detects the position of a component held by the robot, and another camera fixed to a head detects a target position on the board. Then, moving distances in the X-axis and Y-axis directions of the robot are calculated from the component position and the target position, the robot is moved, and the component is mounted to the target position on the board.
In the above-described component mounting apparatus, however, the component position and the target position are detected by separate cameras and the robot is moved based on the component position and the target position, so that the positional accuracy of the cameras and the moving accuracy of the robot directly affect the mounting accuracy of the component. Thus, it is difficult to mount a component to the target position with high accuracy.
Specifically, the moving distances of the robot are calculated from the component position and the target position detected by the respective cameras. If there exists an error in positions of the cameras, therefore, errors may occur in the moving distances. Additionally, errors may occur between the calculated moving distances and the actual moving distances of the robot which is moved based on the calculated moving distances. Moreover, errors may occur in various portions depending on variations in temperature or humidity during the operation. For these reasons, it is difficult to increase the mounting accuracy of a component.
In order to increase the moving accuracy of the robot, it may be contemplated that a linear scale is provided. However, this increases the cost.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a component mounting apparatus which can mount a component at a low cost and with high accuracy.
In order to attain the object, the component mounting apparatus comprises: a component mounting head having a holding unit which holds a supplied component and mounts the component to a predetermined target position, and a camera which detects a position of a target reference mark formed in the vicinity of the target position, detects a holding position of the held component with respect to the holding unit, and simultaneously detects the position of the target reference mark and the holding position; error calculating means for calculating an error of a holding angle of the component on the basis of the position of the target reference mark and the holding position; an angle adjusting mechanism which adjusts an angle of the holding unit on the basis of the holding angle error; and a head moving mechanism which moves the component mounting head on the basis of the position of the target reference mark and the holding position of the component, thereby positioning the component to the target position.
Before holding a component, accordingly, the component mounting head is moved by the head moving mechanism to the target position, and the camera detects the target reference mark. After the detection, a supplied component is held by the holding unit, and the camera detects the holding position of the component with respect to the holding unit. An error of the holding angle of the component is calculated on the basis of the holding position of the component and the position of the target reference mark which is previously detected. Based on the holding angle error, the angle of the holding unit is adjusted by the angle adjusting mechanism, so that the angle of the component is made coincident with the angle of the target position.
Next, the component mounting head is again moved to the target position so that the component is made substantially coincident with the target position. Then, the camera detects the component, and simultaneously detects the target reference mark. Thereafter, the component position is compared with the position of the target reference mark. On the basis of the comparison, the position of the component mounting head is finely adjusted so that the component position is made coincident with the target position, and the component is then mounted.
The operations of detection of the component position, adjustment of the angle, positioning, and the like may be conducted after the component mounting head is moved to the target position in the condition where the head sucks the component.
In the component mounting apparatus, the holding unit disposed on the component mounting head is a suction nozzle which sucks and holds the component, a camera is disposed at two positions located on both sides of the suction nozzle, the angle adjusting mechanism is rotating means for rotating the suction nozzle, means for reciprocating the suction nozzle is disposed on the component mounting head, and the head moving mechanism moves the component mounting head in X-axis and Y-axis directions on a working table.
Accordingly, when a supplied component is to be taken out by the holding unit, the component is sucked and held by the suction nozzle in the condition where the suction nozzle is advanced by the nozzle reciprocating mechanism. Then, the suction nozzle is retracted by the nozzle reciprocating mechanism, so that the component is lifted. When the component is to be mounted to the target position, the suction nozzle is advanced by the nozzle reciprocating mechanism. In this condition, the suction and holding are canceled and the mounting of the component is performed.
When the angle of the holding unit is to be adjusted on the basis of the holding angle error of the component, the suction nozzle is rotated together with the component. The two cameras detect the positions of target reference marks respectively formed in two or more places among which the held component is interposed.
REFERENCES:
patent: 4914513 (1990-04-01), Spigarelli et al.
patent: 5113565 (1992-05-01), Cipolla et al.
patent: 5157734 (1992-10-01), Chen et al.
patent: 5237622 (1993-08-01), Howell
patent: 5251266 (1993-10-01), Spigarelli et al.
Kabushiki Kaisha Sankyo Seiki Seisakusho
Mehta Bhavesh
Sughrue Mion Zinn Macpeak & Seas, PLLC
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