Abstract:
A component mounter which includes a component feeder carriage; mounting head having two or more suction nozzles for picking up a component from the feeder carriage; image capturing means for taking an image of each component held by the suction nozzles; and a recognizer for recognizing each component based on image data obtained by the image capturing means according to a mounting sequence of each component. Each component is immediately and individually mounted on a mounting target after recognition. This configuration allows to eliminate wasteful standby time, thus offering efficient component mounting.

Description:
FIELD OF THE INVENTION 
     The present invention relates to component mounters and mounting methods such as for picking up electronic components from a component feeder carriage and mounting them on a substrate. 
     BACKGROUND OF THE INVENTION 
     A typical component mounter for mounting electronic components on a substrate picks up components stored in a feeder carriage with its mounting head provided with a suction nozzle, transfers them to above the substrate, and mounts them at predetermined mounting points. Before mounting components on the substrate, components are recognized to check their type and any positional deviation. This recognition is implemented by capturing the image of a component held with the mounting head by a camera installed underneath before the mounting operation. 
     Some mounters have a mounting head equipped with two or more suction nozzles for improving the mounting efficiency. This type of mounting head with multiple suction nozzles allows the picking up of two or more components when moving to the feeder carriage and picking up components to increase the efficiency of the pick-up process. After picking up the components, the mounting head moves over the camera to allow component recognition, at which point the image of each component is captured and recognized. Each component is then sequentially mounted at their predetermined mounting points on the substrate while correcting any detected positional deviation. 
     Conventionally, however, recognition is executed for all components held by the mounting head before starting to mount them on the substrate when using a mounting head with multiple nozzles to mount multiple components. This requires considerable time to recognize all the components, particularly if the number of components held by the head increases. Since no mounting takes place during recognition, this extends the overall mounting tact time. Accordingly, to improve the mounting efficiency, it is necessary to eliminate this wasteful time during recognition. 
     SUMMARY OF THE INVENTION 
     The present invention aims to provide a component mounter and mounting method for efficiently mounting components using a mounting head with multiple nozzles. 
     The component mounter of the present invention includes: 
     (a) a component feeder carriage; 
     (b) a mounting head having two or more suction nozzles for picking up components from the feeder carriage; 
     (c) image capturing means for taking the image of each component held with the suction nozzles; and 
     (d) recognizer for recognizing each component using image data obtained through the image capturing means in accordance with a mounting sequence of each component. 
     Each component is mounted on a mounting target (such as substrate), one by one, after recognition. 
     This configuration allows to eliminate a wasteful standby time for improving the component mounting efficiency. 
     The component mounting method of the present invention includes the next steps: 
     (a) picking up components from the feeder carriage using the mounting head with two or more suction nozzles; 
     (b) capturing the image of each component held with the suction nozzles by the image capturing means; 
     (c) recognizing each component, according to its mounting sequence, using the captured image in accordance with a mounting sequence by a recognizer; and 
     (d) mounting the recognized component, one by one onto the mounting target (such as a substrate). 
     In this method, each component is recognized according to its mounting sequence after capturing images. of multiple components. Then, the recognized component is mounted on the substrate immediately. This allows to start the mounting operation without waiting for recognition of all components picked up. Consequently, the efficiency of the component mounting process improves by the elimination of wasteful standby time. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a component mounter in accordance with a preferred embodiment of the present invention. 
     FIG. 2 is a sectional side view of the component mounter in accordance with the preferred embodiment of the present invention. 
     FIG. 3 is a block diagram of a control system in accordance with the preferred embodiment of the present invention. 
     FIG. 4 is a timing chart for the mounting operation of the component mounter in accordance with the preferred embodiment of the present invention. 
     FIG. 5 illustrates how an image is captured in the component mounter in accordance with the preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A preferred embodiment of the present invention is described below with reference to drawings. 
     FIG. 1 is a perspective view and FIG. 2 is a sectional side view of a component mounter in the preferred embodiment of the present invention. FIG. 3 is a block diagram of a control system in a component mounter in the preferred embodiment. FIG. 4 is a timing chart for the mounting operation of the component mounter in the preferred embodiment. FIG. 5 illustrates how an image is captured in the component mounter in the preferred embodiment of the present invention. 
     The configuration of the component mounter in the preferred embodiment of the present invention is described below. 
     In FIG. 1, substrate  12  is placed on transfer rail  11 . Feeder carriage  16  that supplies electronic components is installed at the side of transfer rail  11 . As shown in FIG. 2, two or more tape feeders  18  are placed on feeder base  17  of feeder carriage  16 . Tape feeders  18  feed the tape holding components at a predetermined pitch to supply components to the pick-up position of mounting head  13 . 
     Head  13  is moved horizontally by a driver (not illustrated), and two or more suction nozzles  14  installed at the bottom end of the head  13  pick up components from tape feeders  18  and mount them on substrate  12 , which is the mounting target. Line camera  15 , the image capturing means, is disposed between feeder carriage  16  and transfer rail  11 . Camera  15  captures an image of each component held with nozzle  14  when head  13  holding the component with its nozzle  14  is moved over camera  15 . 
     Next, the configuration of the control system of the component mounter in the preferred embodiment of the present invention is described with reference to FIG.  3 . In FIG. 3, controller  20  is the CPU which controls the entire operation of the component mounter. Program memory  21  stores the programs required for a range of operations, including mounting operation. Mounting data including information on types, mounting sequence, and mounting coordinates of each component to be mounted on substrate  12  are stored in mounting data memory  22 . Mechanical controller  23  controls motors for driving the XY table mechanism for moving the mounting head  13  and the conveyor mechanism of transfer rail  11 . 
     Recognizer  24 , which is the recognition means, recognizes the position of the component held by mounting head  13  using the image data obtained by line camera  15 . Operating and input unit  25  is typically a keyboard or touch panel, and this is used for inputting control commands and data. Display  26  is a monitor for displaying the images captured by camera  15  and the operating menu. 
     The mounting operation of the component mounter of the preferred embodiment as configured above is described next following the chart in FIG.  4 . The chart shows the sequence of steps and their timing while head  13  makes a single round trip between feeder carriage  16  and substrate  12  (one mounting turn). 
     First, head  13  moves to feeder carriage  16 , and picks up one component with each one of multiple nozzles  14  (6 nozzles in the preferred embodiment). The types of the six components to be picked up and which component nozzle  14  will pick up are determined based on the mounting data previously stored in mounting data memory  22 . In other words, each nozzle  14  picks up and mounts a predetermined component according to a predetermined mounting sequence. 
     Mounting head  13 , holding six components by its nozzles  14  by suction, horizontally moves over camera  15  as shown in FIG.  5 . While head  13  moves, camera  15  captures an image of each component P held by each nozzle  14 . The captured image data is sent to recognizer  24  for recognition. 
     In the recognition process, firstly any suction error is detected. At this point, an image of component P on each nozzle  14 , in other words, the presence of a component on each nozzle in the captured image is checked. If component P is missing from any of nozzles  14 , the recognizer  24  determines it as a suction error of detected nozzle  14 . In this case, no position recognition and component mounting operation, which are normally the next steps, are implemented for this particular nozzle  14 . 
     After detection of suction errors, the position of the first component, i.e. the component which is to be mounted first in the sequence of mounting data for the six components picked up during one pickup operation, is recognized. After recognizing the position of the first component, the other components are also recognized one by one in the same way, in accordance with the predetermined mounting sequence. 
     After the position of the first component is recognized, head  13  starts to mount the first recognized component based on the mounting data. The required compensation for correcting positional deviation is calculated based on the position recognition result already obtained, and the first component is mounted on substrate  12  after correcting any positional deviation while the head moves over substrate  12 . During this component mounting operation, the recognizer  24  continues to recognize the positions of other components. Then, in the same way, the components whose position is already recognized are mounted in turn. Mounting of all components in the one mounting turn is complete after recognizing the position of the sixth component and mounting it on the substrate. 
     For comparison, FIG. 4 shows a part of the timing chart for the component mounting operation using the conventional method. It is apparent in FIG. 4 that the preferred embodiment allows reduction of the tact time indicated by time T, compared to the conventional method which starts the entire mounting operation only after the positions of all components are recognized in each mounting turn. 
     As described above, the present invention allows images of multiple components to be captured, an image of each component using captured image data to be recognized according to the component mounting sequence, and each recognized component to be mounted immediately and individually on the substrate without waiting for the completion of recognition of all components picked up before starting the mounting operation. Consequently, the present invention eliminates wasteful standby time and increases the efficiency of the electronic components mounting process.