Method and apparatus for component recognition

Adjustment of image pickup conditions through alternative selection of two cameras different in resolution, adjustment of image lightness of a to-be-recognized component based on component information of the component, and performing control allows an image of the component to be picked up by either one of the cameras under the image pickup conditions.

TECHNICAL FIELD

The present invention relates to a component recognition device and a method thereof for image recognition of components, especially electronic components, in a case where the electronic components are recognized as images and placed on circuit forming bodies, as well as to a component mounting apparatus including the component recognition device and a component mounting method including the component recognition method.

BACKGROUND ART

FIG. 11is a plan view showing a main part of a conventional component mounting apparatus,FIG. 12is a enlarged cross sectional view showing an image pickup unit ofFIG. 11, andFIG. 13is a schematic timing chart showing operation of each section in response to rotation of a rotary index table shown inFIG. 11. On a periphery of rotary index table111(hereinafter referred to as index table111), suction nozzles112are installed.

A component feeding section120feeds each of a plurality of electronic component feeding units121, storing various electronic components, to a lower side of a suction nozzle112moved to a suction position in accordance with control instructions. The suction nozzle112sucks an electronic component113from an electronic component feeding unit121, and then rotation of the index table111moves the suction nozzle112to a recognition position (time t1(FIG. 13)).

Once the suction nozzle112sucking and holding the electronic component113moves to the recognition position, with a lapse of vibration damping waiting time (time t1to t2), LEDs136and137on a component image pickup unit130adequately illuminate the electronic component, so that first and second cameras131and132receive exposure from the electronic component via a mirror133, a half mirror134, and a further mirror135(time t2to t3), and a taken image signal of the electronic component113is transmitted to an image processing unit based on NTSC method or the like (time t3to t5). During transmission of the image signal to the image processing unit, the suction nozzle112that sucked the electronic component113starts to move to a placement position (time t4).

In a super high-speed component mounting apparatus, a series of processing operations including these operations is repeatedly executed in, for example, 80 ms tact. It is noted that the first and second cameras131and132in this example are both provided with, for example, about 250,000-pixel resolution, and each is equipped with an optical system different in terms of target components such that image pickup of a small component is performed by the first camera131while image pickup of a large component is performed by the second camera132.

As for semiconductor devices, a degree of integration is incremental for implementation of a multifunction and the like, and large-size high-accuracy electronic components are increasing while smaller electronic components are also being manufactured. These circumstances are shown in an electronic component measurement table ofFIG. 14. As shown in this table, electronic components include BGA (Ball grid Array) whose side length is about 32 mm, and there are also manufactured unshown larger-sized electronic components. It is noted that inFIG. 14, mini Tr denotes a mini-transistor, tantalum C denotes a tantalum capacitor, chip L denotes a large chip component that is larger than a chip component up to 0.6 to 3.2 mm, power Tr denotes a power transistor, aluminum electrolytic C denotes an aluminum electrolytic capacitor, SOJ refers to Small Outline J Lead Package, PLCC refers to Plastic Leaded Chip Carrier, SOP refers to Small Outline Package, CSP (0.5 p to 0.8 p) refers to Chip Sized Package having interelectrode pitches of 0.5 to 0.8 mm, and BGA (0.1 p−) refers to Ball Grid Array having interelectrode pitches of at least 0.1 mm. The numeral0603denotes a chip component having a size of 0.6 mm×0.3 mm, the numeral2125denotes a chip component having a size of 2.1 mm×2.5 mm, the numeral3216denotes a chip component having a size of 3.2 mm×1.6 mm, the □18 denotes a square chip component having a side length of 18 mm, and the □32 denotes a square chip component having a side length of 32 mm.

According to the conventional component mounting apparatus described with reference toFIGS. 11 and 12, if the first and second cameras131and132of a same kind having approximately 250,000-pixel resolution are each equipped with optical systems suitable in size for components subjected to image pickup, the first and second cameras131and132can at best perform good image pickup and image recognition of electronic components within respective ranges L1and L2as shown in the conventional method inFIG. 14(up to a side length of about 18 mm).

This is, for example, because if the optical system mounted on the second camera is changed to enlarge the image pickup range, the small number of pixels thereof disturbs clear recognition of individual terminals (pins and balls) in an electronic component. An example thereof is shown inFIG. 15, wherein although an image EZ0of an electronic component is obtained by the second camera as an image EZ1, an image of terminals thereof becomes unclear.

It is naturally considerable that as an extension of this conventional technology, a unit number of cameras is increased, for example, to three units, so that a third camera may be used for components having a side length of about at least 18 mm. However, this complicates structure and brings about high costs, and size of the image pickup unit itself becomes large and heavy, thereby causing an issue of susceptibility to influence of mechanical vibration.

Accordingly, for solving the above issue, it is an object of the present invention to provide a component recognition device and a method thereof as well as a component mounting apparatus and a method thereof enabling image pickup of small components to large components of approximately the same image pickup quality while maintaining good resolution for image recognition with use of image pickup units, for example two cameras, and enabling image processing while maintaining high-speed tact.

SUMMARY OF THE INVENTION

In order to accomplish the above object, the present invention has the following constitutions.

According to a first aspect of the present invention, there is provided a component recognition device for recognizing and processing a picked-up image of a component, comprising:

an illumination unit for emitting illumination light to the component when held by a component holding member and to be placed on a circuit forming body;

a first image pickup unit for recognizing this illuminated component;

a second image pickup unit for recognizing the illuminated component with resolution higher than that of the first image pickup unit; and

a control section for enabling adjustment of image pickup conditions through alternative selection of the first image pickup unit and the second image pickup unit and through adjustment of image lightness of a component to be recognized, based on component information of this component, and thus controlling such that an image of the component is picked up by either one of the image pickup units under the image pickup conditions.

According to a second aspect of the present invention, there is provided a component recognition device as defined in the first aspect,

wherein the illumination unit is provided with plural kinds of illumination sources capable of illuminating the component with different kinds of illumination light, and being different in terms of their disposed position relative to a component, and

wherein the control section adjusts the image pickup conditions through adjustment of an illuminance of illumination from the illumination unit to the component, through selection of kinds or positions of plural kinds of the illumination sources or selection of the kinds and the positions of plural kinds of the illumination sources, or through adjustment of an illuminance of illumination from the illumination unit to the component and selection of kinds or positions of plural kinds of the illumination sources or selection of kinds and positions of plural kinds of the illumination sources, based on component information of the component, and thus controls such that an image of the component is picked up by one of the image pickup units.

According to a third aspect of the present invention, there is provided a component recognition device as defined in the first or second aspect,

wherein the control section adjusts the image pickup conditions through adjustment of an exposure time of a corresponding one of the image pickup units based on the component information of the component, and thus controls such that an image of the component is picked up by the corresponding one of the image pickup units.

According to a fourth aspect of the present invention, there is provided a component recognition device as defined in any one of the first to third aspects,

wherein the control section adjusts the image pickup conditions through adjustment of image signal gain so as to be suited for image recognition based on the component information of the component to eliminate difference in lightness of the image to be picked up due to difference in performance between the first image pickup unit and the second image pickup unit and kind of the component, and thus controls such that an image of the component is picked up by a corresponding one of the image pickup units.

According to a fifth aspect of the present invention, there is provided a component recognition device as defined in any one of the first to fourth aspects,

wherein the control section adjusts the image pickup conditions through adjustment of a readout clock frequency of the second image pickup unit to be higher than a readout clock frequency of the first image pickup unit if the second image pickup unit is selected based on the component information of the component, and thus controls such that an image of the component is picked up by a corresponding one of the image pickup units.

According to a sixth aspect of the present invention, there is provided a component recognition device as defined in any one of the first to fifth aspects,

wherein the control section adjusts the image pickup conditions through setting of a scan spacing of a component image picked up by one of the image pickup units in accordance with this image pickup unit and kind of the component based on the component information of the component, and thus controls such that an image of the component is picked up by this image pickup unit,

with the component recognition device further comprising an image recognition processing section for scanning a picked-up component image based on the scan spacing of the component image set by the control section in accordance with the image pickup unit and kind of the component, recognizing a component existing region in the component image, and then performing image recognition in a recognized component existing region as an image so as to enable posture recognition of the component.

According to a seventh aspect of the present invention, there is provided a component recognition device as defined in any one of the first to sixth aspects,

wherein the illumination unit has an illumination source for emitting illumination light for illuminating the component, whose illumination direction is other than a direction orthogonal to any side of the component.

According to an eighth aspect of the present invention, there is provided a component recognition device as defined in any one of the first to seventh aspects,

wherein the illumination unit is composed of a light diffusing plate disposed opposite to the image pickup units relative to the component and above the component when held by the component holding member, an illumination source for emitting illumination light for illuminating the component downwardly, and a reflection section for reflecting illumination light emitted from the illumination source upwardly toward the light diffusing plate,

with the illumination light emitted from the illumination source being reflected by the reflection section upwardly toward the light diffusing plate, the illumination light being diffused by the light diffusing plate, and an outline image of the component being picked up by either one of the image pickup units with the diffused light.

According to a ninth aspect of the present invention, there is provided a component recognition device as defined in any one of the first to eighth aspects,

wherein the control section selects the second image pickup unit if, in component information of a component, the component is a lead component, or a C4 component of a BAG or a CSP, and selects the first image pickup unit if the component is a chip component based on the component information of the component.

According to a tenth aspect of the present invention, there is provided a component recognition device as defined in the third aspect,

wherein the control section prolongs an exposure time if, in the component information of the component, an electrode of the component has difficulty in reflecting light based on the component information of the component.

According to an eleventh aspect of the present invention, there is provided a component recognition device as defined in the second aspect,

wherein plural kinds of illumination sources of the illumination unit, different in terms of their disposed position, are composed of an illumination source disposed so as to be able to emit illumination light for illuminating the component from almost right under the component, and an illumination source disposed so as to be able to emit illumination light for illuminating the component from an inclined lower side of the component, and

wherein the control section controls the illumination light from the illumination source so as to be emitted from almost right under the component if an electrode of the component is in a mirror state based on the component information of the component.

According to a twelfth aspect of the present invention, there is provided a component recognition method comprising:

adjusting image pickup conditions, based on component information of a component held by a component holding member and to be placed on a circuit forming body, through alternative selection of a first image pickup unit and a second image pickup unit having resolution higher than that of the first image pickup unit, and through adjustment of image lightness of the component to be recognized by either one of the image pickup units;

illuminating the component with illumination units under the image pickup conditions;

picking up an image of the illuminated component with one of the image pickup units under the image pickup conditions; and

performing component recognition based on the picked-up image.

According to a thirteenth aspect of the present invention, there is provided a component recognition method as defined in the twelfth aspect,

wherein when the image pickup conditions are adjusted, an illuminance of illumination from the illumination unit to the component is adjusted, or kinds or positions of plural kinds of illumination sources are selected or the kinds and the positions of plural kinds of the illumination sources are selected, or an illuminance of illumination from the illumination unit to the component is adjusted and kinds or positions of plural kinds of the illumination sources are selected or the kinds and the positions of plural kinds of the illumination sources are selected based on the component information of the component.

According to a fourteenth aspect of the present invention, there is provided a component recognition method as defined in the twelfth or thirteenth aspect, wherein when the image pickup conditions are adjusted, an exposure time of one image pickup unit is adjusted based on the component information of the component.

According to a fifteenth aspect of the present invention, there is provided a component recognition method as defined in any one of the twelfth to fourteenth aspects, wherein when the image pickup conditions are adjusted, image signal gain is adjusted so as to be suited for image recognition based on the component information of the component to eliminate difference in lightness of the image to be picked up due to difference in performance between the first image pickup unit and the second image pickup unit and kind of the component.

According to a sixteenth aspect of the present invention, there is provided a component recognition method as defined in any one of the twelfth to fifteenth aspects, wherein when the image pickup conditions are adjusted, a readout clock frequency of the second image pickup unit is adjusted to be higher than a readout clock frequency of the first image pickup unit if the second image pickup unit is selected based on the component information of the component.

According to a seventeenth aspect of the present invention, there is provided a component recognition method as defined in any one of the twelfth to sixteenth aspects, wherein

when the image pickup conditions are adjusted, a scan spacing of a component image picked up by the image pickup unit is set in accordance with the one image pickup unit and kind of the component based on the component information of the component, and

when component recognition is performed based on the picked-up image, the picked-up component image is scanned based on a scan spacing of the component image set in accordance with the one image pickup unit and kind of the component, a component existing region in the component image is recognized, and then image recognition is performed in the recognized component existing region so as to enable posture recognition of the component.

According to an eighteenth aspect of the present invention, there is provided a component recognition method as defined in any one of the twelfth to seventeenth aspects, wherein when the component is illuminated with the illumination unit under the image pickup conditions, illumination direction of illumination light emitted to the component is other than a direction orthogonal to any side of the component.

According to a nineteenth aspect of the present invention, there is provided a component recognition method as defined in any one of the twelfth to eighteenth aspects, wherein when the component is illuminated with the illumination unit under the image pickup conditions, illumination light emitted from an illumination source is reflected by a reflection section upwardly toward a light diffusing plate disposed opposite to the image pickup unit relative to the component, and the illumination light is diffused by the light diffusing plate, and

when an image of the illuminated component is picked up by either one of the image pickup units under the image pickup conditions, an outline image of the component is picked up with light diffused by the light diffusing plate.

According to a twentieth aspect of the present invention, there is provided a component recognition method as defined in any one of the twelfth to nineteenth aspects, wherein when the image pickup conditions are adjusted, the second image pickup unit is selected if, in the component information of the component, the component is a lead component, or a C4 component of a BAG or a CSP, while the first image pickup unit is selected if the component is a chip component.

According to a twenty-first aspect of the present invention, there is provided a component recognition method as defined in the fourteenth aspect, wherein when the image pickup conditions are adjusted, an exposure time is prolonged if, in the component information of the component, an electrode of the component has difficulty in reflecting light.

According to a twenty-second aspect of the present invention, there is provided a component recognition method as defined in the thirteenth aspect, wherein when the image pickup conditions are adjusted, the illumination light from the illumination source is controlled so as to be emitted from almost right under the component if an electrode of the component is in a mirror state.

According to a twenty-third aspect of the present invention, there is provided a component mounting apparatus comprising:

the component recognition device as defined in any one of the first to eleventh aspects; and

a component holding member for holding the component at a component holding position and moving the component along a moving route to a placement position of a circuit forming body through a recognition position,

with the component mounting apparatus illuminating the component when held by the component holding member with the illumination unit of the component recognition device at the recognition position on the moving route to perform recognition processing of the image of the component picked up by the image pickup unit, and correcting a posture of the component holding member relative to the placement position based on a result of recognition processing.

According to a twenty-fourth aspect of the present invention, there is provided a component mounting method with the component holding member provided for holding the component at a component holding position and moving the component along a moving route to a placement position of the circuit forming body through a recognition position, comprising:

illuminating the component held by the component holding member with the illumination unit of the component recognition device at the recognition position on the moving route to perform recognition processing of the component image picked up by the image pickup unit in the component recognition method as defined in any one of the twelfth to twenty-second aspects;

then correcting a posture of the component holding member relative to the placement position based on a result of the recognition processing; and

placing the component held by the component holding member on the placement position of the circuit forming body.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A first embodiment of the present invention will be described hereinafter in detail with reference to drawings.

Embodiments of the present invention will be described hereinafter in detail with reference to drawings.

FIG. 1is a perspective view showing an appearance of an electronic component mounting apparatus having a component recognition device according to one embodiment of the present invention,FIG. 2is a view showing an electronic component mounting mechanism in a central portion of the electronic component mounting apparatus ofFIG. 1,FIG. 3is a view showing a rotary index table portion in the electronic component mounting mechanism ofFIG. 2seen from above,FIGS. 4A and 4Bare an external view and a schematic plan view each showing a component recognition device ofFIG. 3and a layout of green LEDs of the component recognition device,FIG. 5is a cross sectional view showing structure of the component recognition device ofFIG. 4A, andFIG. 6is a block diagram showing relationships of each section relating to image processing that performs image processing such as the component recognition device of the electronic component mounting apparatus ofFIG. 1. In the electronic component mounting apparatus, an electronic component as an example of a component is subjected to component recognition in a state of being sucked and held by a suction nozzle12as an example of a component holding member, and then is placed on a board that is an example of a circuit forming body on which a circuit is formed. The circuit forming body refers to an object on which a circuit is formed including circuit boards such as resin boards, paper-phenol boards, ceramic boards, glass epoxy boards, and film substrates; circuit boards such as single layer boards and monolayer boards; components; cases; frames; and the like. Also, an image pickup unit is, more particularly, made up of a first image pickup unit and a second image pickup unit, and in the present embodiment there are used a first camera31as an example of the first image pickup unit and a second camera32as an example of the second image pickup unit.

FIG. 7is a block diagram showing a camera control unit ofFIG. 6in detail,FIG. 8is a flow chart describing operation of a control unit of a camera interface unit ofFIG. 6for selecting either the first camera or the second camera based on information on image pickup conditions read from a memory unit and recognizing a posture of an electronic component sucked by a suction nozzle,FIGS. 9A to 9Dare explanatory views showing a method of shortening time for the control unit ofFIG. 7to perform posture recognition of an electronic component according to instructions from the image processing unit, andFIG. 10is a cross sectional view showing structure for illumination to a light diffusing plate80.

The component recognition device in the above embodiment is composed of illumination units36,37,38for emitting illumination light to a component13held by a suction nozzle12and to be placed on a circuit board18, the first camera31for recognizing illuminated component13, the second camera32for recognizing the illuminated component13with resolution higher than that of the first camera31, and a control section66for enabling adjustment of image pickup conditions per an image pickup operation or per a plurality of image pickup operations or with arbitrary timing, through alternative selection of the first camera31and the second camera32and through adjustment of image lightness of the component13to be recognized based on component information of the component13, and controlling such that an image of the component13is picked up by either one of the cameras under the image pickup conditions, and performs recognition processing of a picked-up image of the component13. By providing such a component recognition device for the electronic component mounting apparatus, a posture of the suction nozzle12relative to a placement position of the circuit board18(e.g. an angle of rotation about an elevating shaft of the suction nozzle12) is corrected based on a result of recognition processing performed by the component recognition device, and then, the component13held by the suction nozzle12is placed on the placement position of the circuit board18.

Examples of component information of the component13include: component characteristic information such as size, height, and kind of the component13, and whether or not electrodes thereof are mirror finished surfaces; adjustment information based on the component characteristic information such as adjustment information on how to adjust lightness of an image of the component; adjustment information on illuminance of illumination from the illumination unit to the component; selection information on kinds and positions of plural kinds of illumination sources (such as whether or not illumination direction of illumination light emitted to the component is a direction other than a direction orthogonal to any side of the component, whether illumination light emitted to the component is disposed so as to be able to illuminate the component from almost right under the component, and whether illumination light emitted to the component is disposed so as to be able to illuminate the component from an inclined lower side of the component); adjustment information on exposure time of a corresponding image pickup unit; adjustment information on image signal gain suitable for image recognition; information of the illumination unit to be selected based on whether or not the electrodes of the component have difficulty in reflecting light; and information of the illumination unit to be selected based on whether or not the electrodes of the component are in mirror-states. Therefore, the control section66obtains component characteristic information of a component13to be placed next, obtains adjustment information based on the component characteristic information, and then adjusts image pickup conditions based on the adjustment information.

With reference toFIGS. 1 to 5, description will be first given of structure of an electronic component mounting apparatus10having the component recognition device. The electronic component mounting apparatus10has an image pickup unit30and a circuit portion for controlling the image pickup unit30whose structure is largely different from that of a conventional electronic component mounting apparatus. In the central portion of the electronic component mounting apparatus10, there is disposed a rotary index table11(hereinafter referred to as index table11) having a plurality of suction nozzles12installed on a periphery thereof at equal intervals. The index table11rotates by a constant angle in response to instructions from the control section66(further described later) to move each suction nozzle12along a moving route through a suction position exemplifying a component holding position, a recognition position, and a placement position (seeFIG. 3), and then again through the suction position, the recognition position, and the placement position in a repeating manner.

A component feeding section20installs a plurality of electronic component feeding units21(seeFIG. 2) in parallel, and moves an electronic component feeding unit21accommodating electronic components necessary for a placement operation to the suction position. Once the electronic component feeding unit21is placed at the suction position, a suction nozzle12sucks an electronic component13from the electronic component feeding unit21.

When the suction nozzle12sucks the electronic component13, the index table11rotates to move the suction nozzle12to the recognition position. In the recognition position, there is disposed a mechanism section (refer toFIG. 6andFIG. 7for the control section66) of the image pickup unit30(seeFIG. 3).

The image pickup unit30is provided with green LEDs36,38and a red LED37for illuminating the electronic component13in a position under the suction nozzle12stopped in the recognition position, that exemplifies an illumination source of the illumination unit, as well as provided with the first camera31and the second camera32on a lateral side thereof as shown inFIG. 4A,FIG. 4B, andFIG. 5. Here, the green LED36, a couple of which is composed of a plurality of green LEDs, more particularly, a total of four LEDs formed by combining two rows of two LEDs disposed in parallel, is provided to a periphery of an opening100aof a later-described illumination unit case100such that an illumination direction of green illumination light from each green LED36is not a direction orthogonal to an arbitrary side of an electronic component subjected to image pickup but is, for example, a direction approximately diagonal to the electronic component13as shown inFIG. 4B. As for the red LED37, a couple thereof is composed of, for example, four LEDs disposed in a row, and this couple composed of four LEDs is disposed so as to face each other along a parallel direction of the first camera31and the second camera32as shown inFIG. 4A. Also, another green LED38, a couple of which is composed of five LEDs, is disposed in a direction orthogonal to the parallel direction of the first camera31and the second camera32, and parallel to an optical axis direction of the first camera31and the second camera32so as to face each other with an optical axis for taking a recognition image from the component to the first camera31and the second camera32(an optical axis for passing light representing an image of the electronic component13illuminated by the LEDs36,37,38) interposed therebetween.

It is noted that the green LEDs36,38are used for reflection while the red LED37is used for transmission. This is because transmission requires certain quantity of light, and therefore use of the red LED37is more preferable than use of the green LEDs36,38.

Consequently, the green LEDs36,38are used for picking up an image of light made up of illumination light reflected by the component13(in other words, light representing an image of the component13) with use of either one of the cameras31and32, whereas the red LED37is preferably used for picking up an image of only an appearance (in other words, a shadow) of the component13with diffused light formed by transmitting LED illumination light to a position higher than the component13and extending it to a diffusing plate above the component13for diffusion as described later in detail with use of either one of the cameras31and32.

Light (or shadow in other methods) representing an image of the electronic component13emitted by these LEDs36,37,38is, as shown inFIG. 5, reflected by a mirror33, and one part of this reflected light is reflected by a half mirror34(beam splitter) and directed to the first camera31while another part of the reflected light passes through the half mirror34and is reflected by a mirror35and directed to the second camera32. It is noted that the first camera31and the second camera32are secured to the illumination unit case100in parallel so that each optical axis is in parallel. The mirror33is slantingly secured right under the opening100aon one end of the illumination unit case100beneath the recognition position of the component13. The half mirror34is slantingly secured in a central portion of the illumination unit case100and beneath the first camera31. The mirror35is slantingly secured beneath the second camera32on another end of the illumination unit case100.

In the above-stated example, the first camera31is equipped with, for example, a conventional 250,000-pixel image device (e.g. CCD), while the second camera32is equipped with, for example, a 1,000,000-pixel image device having resolution higher than the first camera31. When the image pickup unit30having such structure recognizes a posture of the electronic component13being sucked by the suction nozzle12(a posture herein includes an outline posture, and, where necessary, positions of external terminals (pins and balls)), the index table11intermittently rotates to move the suction nozzle12to the placement position.

In the placement position, there is disposed an XY table15exemplifying a board holding unit which holds the circuit board18and a position of which is adjusted relative to the placement position in X and Y directions, for positional adjustment for every mounting operation, by an X-directional drive mechanism16X and a Y-directional drive mechanism16Y. On the XY table15, there is fed a circuit board18from a feeding-side board transfer section19athat is a loader composed of, for example, a pair of belt conveyor transfer rails, and this circuit board18with all components mounted thereon is delivered to a discharge-side board transfer section19bthat is an unloader composed of, for example, a pair of belt conveyor transfer rails. According to a suction state (suction posture) of the electronic component13, a position of the XY table15is adjusted, and the electronic component13being sucked by the suction nozzle12is placed on the circuit board18on the XY table15. Once placement of the electronic component13from the suction nozzle12is completed, the index table11rotates again and returns emptied suction nozzle12to the suction position one by one for repeating a series of operations. In the Y-directional drive mechanism16Y, forward and reverse rotation of a motor16dreciprocally rotates a ball screw16e. A nut member16ffixed on a Y table16gengages with the ball screw16e, so that forward and reverse rotation of the ball screw16ebrings about advance and retreat of the Y table16galong Y direction through the nut member16f. On the Y table16g, there is disposed the X-directional drive mechanism16X. In the X-directional drive mechanism16X, forward and reverse rotation of a motor16areciprocally rotates a ball screw16b. A nut member16cfixed on the XY table15engages with the ball screw16b, so that forward and reverse rotation of the ball screw16bbrings about advance and retreat of the XY table15along X direction through the nut member16c. Therefore, the XY table15is advanced and retreated in Y direction by the Y-directional drive mechanism16Y, and also moved forward and backward in X direction by the X-directional drive mechanism16X.

As shown inFIG. 6andFIG. 7, an image processing unit60, functioning as an example of an image recognition processing section that performs image processing of the image pickup unit30and the like in the electronic component mounting apparatus10, is composed of, as one example, a main machine controller61that also performs control of other mechanism units, a sequence controller62, a man-machine interface63, and a bus64for connecting these members. Conforming to instructions from the sequence controller62, an interface unit66of a camera control unit65reads image pickup conditions information (for example, image pickup conditions information inputted by an input-output unit69of a computer and the like and stored) stored in advance in a memory unit67corresponding to a kind of an electronic component subjected to posture recognition, outputs various instructions or signals from a camera control signal generator66c, and performs predetermined operations for optimum image processing. The interface unit66functions as an example of the control section. Input of the image pickup conditions information is executed by reading the image pickup conditions information produced and recorded in advance from a storage medium such as a CD-ROM with the input-output unit69, or the image pickup conditions information may be inputted through the input-output unit69of a computer and the like by communication and then stored in the memory unit67in advance. Also, in addition to storing in advance before starting a mounting operation of the component mounting apparatus, appropriate modifications and updates corresponding to mounting operation contents during the mounting operation of the component mounting apparatus is acceptable.

The interface unit66makes reference to information on image pickup conditions read from the memory unit67, and instructs camera control signal generator66c. The camera control signal generator66cselects the first camera31or the second camera32via a camera control signal output selecting section66din response to kind (such as size) of an electronic component subjected to posture recognition, and gives illumination control instructions to, for example, the illumination unit38to execute illumination conforming to the image pickup conditions from the memory unit67so as to decrease difference in lightness between image pickup by the first and second cameras31and32. For example, in order to select a camera having optimum resolution for a size of a component, or spacing of electrodes or leads thereof, the second camera32having higher resolution is selected if the component is a component requiring high precision placement including a lead component having lead spacing with small pitches, or a C4 (Controlled Collapse Chip Connection) component such as a BGA (Ball Grid Array) or CSP (Chip Sized Package), while the first camera31having lower resolution is selected if the component is a chip component. In a case of a component such as a QFP (Quad Flat Package) or BGA whose leads or electrodes are in mirror states, illumination light is emitted from almost directly beneath by the LED36for example. This is because inclined illumination causes diffused reflection of the electrodes, thereby hindering recognition. For other normal components, illumination from an inclined angle of 45 degrees is preferable.

Also, depending on given image pickup conditions, the camera control signal generator66ccontrols exposure times of the first and second cameras31and32so as to decrease difference in lightness of image pickup due to a kind of a component subjected to posture recognition and difference between the first and second cameras31and32. For example, if electrodes of a component subjected to posture recognition are difficult to shine, as is a case of a plated electrode, more particularly difficult in reflecting light, exposure times of the first and second cameras31and32are prolonged. Alternately, the camera control signal generator66ccontrols gain and dynamic range of an A/D converter67fto control so as to decrease difference in lightness of image pickup due to the kind of the component subjected to posture recognition or a difference between the first and second cameras31and32. Further, the camera control signal generator66cuses an output of, for example, a 12-MHz oscillator66aas a readout clock if the first camera31is selected while using an output of, for example, a 20-MHz oscillator66bas a readout clock if the second camera32is selected, for executing switch control so as to eliminate a difference in output readout time between the cameras31and32. More particularly, if the second camera32is selected, readout clock frequency of the second camera32is adjusted to be higher than readout clock frequency of the first camera31, for eliminating image readout delay in using the second camera32in comparison with usage of the first camera31, thereby enabling elimination of tact (process) delay.

This enables maintenance of high-speed tact. Since image pickup of the circuit board18is necessary when the electronic component13is moved to the placement position, the camera control signal generator66ccontrols to make a board image pickup camera39pick up an image of the circuit board18, for performing placement of the electronic component13on the circuit board18.

Next, description will be given of operation, in the recognition position, of selecting either one of the first and second cameras31and32according to image pickup conditions read from the memory unit67by the interface unit66of the camera control unit65included in the control section66of the image pickup unit30, and then recognizing a posture of the electronic component13sucked by the suction nozzle12, with reference toFIG. 8.

In this case, in terms of various settings stated above such as setting of the illumination unit38, setting of exposure times of the first and second cameras31and32, and setting of output gains of the first camera31and the second camera32, it is already determined whether only either any one setting is conducted or setting is made in combination, under a condition of which operation of selecting the first and second cameras31and32, and posture recognition of the electronic component13by this selected first or second camera31or32will be described.

Component data that is component information of a component subjected to placement is inputted from a sequence controller62(Step S1). Corresponding to rotation of the index table11, stoppage in the recognition position is performed (Step2), and it is decided whether the first camera31for small view should be used or the second camera32for large view should be used, with reference to a size of the electronic component based on component data inputted in step S1depending on the component being sucked by the suction nozzle12(Step S3).

If, in step S3, the first camera31for small components is used, all pixels of an image inputted from the first camera31are scanned (Step S4). In step S3, if it is decided that the second camera32for large components should be used, it is further decided if this large electronic component13subjected to posture recognition belongs to precision components, belongs to middle-size components, or belongs to large-size components among large components (Step S5). It is naturally understood that not only division into three sections but also division into more than three sections are acceptable here.

In step S5, if it is decided that the component belongs to the precision components, a first rough recognition with, for example, “scan spacing4” is conducted for scanning pixels of an image inputted from the second camera32(Step S6). If it is decided that the component belongs to the middle-side components, pixels of an image inputted from the second camera32undergoes a second rough recognition with, for example, “scan spacing8” that is rougher than that of the precision components (Step S7). If it is decided that the component belongs to the large-size components, pixels of an image inputted from the second camera32undergoes a third rough recognition with, for example, “scan spacing10”, that is rougher than that of the middle-size components (Step S8). It is noted that the scan spacing4refers to a scan performed by every four scanning lines, scan spacing8refers to a scan performed by every eight scanning lines, and scan spacing10refers to a scan performed by every ten scanning lines.

As a result of each rough recognition depending on kinds of components in steps S6, S7, and S8, a region in a recognized image occupied by an image of the electronic component13is roughly clarified. Accordingly, a part unnecessary for posture recognition of the electronic component13is removed and posture recognition is performed by precise scan (e.g. full scan) of the electronic component13in an appropriate region including a region in which the electronic component13exists (Step S9). In performing this precise posture scan, performing posture recognition of the electronic component13by limiting a target to a necessary minimum region enables execution of tact in a shorter period of time. When posture recognition is completed, a recognition result is outputted (Step S10) and returned to the main machine controller61for use in correction of a position for placing the electronic component13in a placement position on the circuit board18.

Description will be given of one example of a method of shortening time for the image recognition processing section60to perform posture recognition of the electronic component13when the second camera32is selected as described above, with reference toFIG. 9AtoFIG. 9D. In a case of scanning 1,000,000 pixels (872 lines×1200) of an image device P (e.g. CCD) of the second camera32shown inFIG. 9A, existing regions of large components are recognized as shown inFIG. 9B,FIG. 9CandFIG. 9Dby first, second, and third rough recognition according to division of the large components as in steps S6, S7, and S8shown inFIG. 8.

In a case ofFIG. 9BandFIG. 9C, a shaded portion on a lower side is out of a target for pixel read for precise posture recognition. Accordingly, although scan of 872 lines is originally required, scan of 533 lines or 702 lines is sufficient. Further, as a method of shortening time for posture recognition, an upper portion symmetrical to this shaded lower portion may also be out of the target for precise posture recognition. It is also possible to confine the target for read for precise posture recognition to inside of a dotted line shown inFIG. 9BandFIG. 9C.

InFIG. 10, an LED that is an illumination source disposed right under the index table11in the recognition position is placed lower than the light diffusing plate80and displaced on an upper side of a plane PL on an upper side of an image pickup camera. On a periphery of the LED, there is provided a louver81for preventing diffusion of light and concentrating light with use of a condenser lens83that is a condensing section, so that the light is reflected upwardly toward the light diffused plate80by a mirror82disposed on the plane PL and a prism84. In this case, the camera picks up an image of the electronic component13as an outline (shadow outline). In other words, the illumination unit ofFIG. 10is composed of the light diffusing plate80disposed opposite to the camera against the component13and above the component13held by the suction nozzle12, the LED exemplifying an illumination source for emitting illumination light illuminating the component13downwardly, and the mirror82exemplifying a reflection section for reflecting the illumination light emitted from the LED upwardly toward the light diffusing plate80. The illumination light emitted from the LED is reflected by the mirror82upwardly toward the light diffused plate80, the illumination light is diffused by the light diffused plate80, and an outline image of the component13is picked up by the first or second camera31or32with the diffused light.

In a case where an LED is conventionally disposed on an upper side of plane PL for directly illuminating a light diffusing plate, an angle of reflected light to the plane is approximately 15°. However in this example, when the angle is around 30° or so, the illumination angle is considerably increased as well as quantity of diffused light being increased. This implements good image recognition. Also, this illumination structure makes it possible to make a distance between the light diffusing plate80and the image pickup unit identical to a conventional distance.

It will be understood that the present invention is not limited to the embodiment disclosed, but may be embodied in other specific forms. For example, in the illumination unit ofFIG. 10, it is possible that use of a high-luminance LED saves the condenser lens83and the prism84, and achieves a specified effect only with the mirror82. Also, disposing the LED so that light emitted from the LED comes into a lower side of the prism84at an angle equal to or larger than a critical angle, and generating total reflection of the light under the prism84, enables achievement of a specified effect without the mirror82.

According to the above embodiment, image pickup conditions are adjusted based on component information of the component13held by the suction nozzle12, exemplifying the component holding member, and to be placed on the circuit board18exemplifying the circuit forming body, through alternative selection of the first camera31exemplifying the first image pickup unit and the second camera32exemplifying the second image pickup unit having resolution higher than that of the first camera31, and through adjustment of image lightness of the component13recognized by either one of the cameras. Under the image pickup conditions, the component13is illuminated with the LEDs36,38or the LED37exemplifying the illumination unit, so that an image of the illuminated electronic component13is picked up under the image pickup conditions by either one of the cameras, and component recognition is performed based on this picked-up image. This enables optimum camera selection corresponding to kind of the component13and enables adjustment of image lightness of the component13recognized by the camera, thereby providing an image with resolution corresponding to the component13in a short period of time.

With an image-reception section of a camera with high resolution having a large number of pixels, a clear image such as an image EZ2shown inFIG. 15is obtainable. Consequently, simple usage of two kinds of cameras including a conventional camera with low resolution having a small number of pixels and a camera with high resolution causes an issue that image pickup in uniform quality (seamless image pickup) is not attainable because switchover of the cameras brings about considerable difference in image lightness due to difference in characteristics between these two kinds of cameras. Also, a large number of pixels require longer time for readout, thereby making it difficult to maintain the above-stated tact.

As described above, even if the first camera31and the second camera32with resolution higher than that of the first camera31are disposed in parallel, the control section66controls operation so as to eliminate difference in image quality due to difference in performance between the cameras31and32and a kind of component13and, enable seamless selection of the first and second cameras31and32, and implement clear image pickup of large electronic components with resolution necessary for image recognition with use of the second camera32. Also in the above embodiment, there is provided a structure of having two cameras31and32, which is stronger for vibration than a structure of having at least three cameras.

Also in the above embodiment, when the image pickup conditions are adjusted, illuminance of illumination from the illumination unit to a component may be adjusted or kinds or positions of plural kinds of illumination sources may be selected based on component information of the component.

Thus, changing illuminance of illumination to the electronic component, a kind of the illumination, or a position of the illumination based on information of the electronic component, and selection of the two image pickup units makes it possible to eliminate difference in lightness of an image to be picked up due to difference in performance between both image pickup units and the kind of the electronic component.

Also in the above embodiment, when the image pickup conditions are adjusted, exposure time of an image pickup unit may be adjusted based on the component information.

Thus, changing exposure time of a selected image pickup unit based on information of the electronic component and selection of the image pickup unit, makes it possible to eliminate difference in lightness of an image to be picked up due to difference in performance between the image pickup units and the kind of the electronic component.

Also in the above embodiment, when the image pickup conditions are adjusted, an image signal gain may be adjusted so as to be suited for image recognition based on the component information of the component to eliminate difference in lightness of the image to be picked up due to difference in performance between the first image pickup unit and the second image pickup unit and the kind of the component.

Thus, controlling an image signal gain so as to be suited for image recognition makes it possible to eliminate difference in lightness of an image to be picked up due to difference in performance of both the image pickup units and the kind of the component.

Also in the above embodiment, when the image pickup conditions are adjusted, a readout clock frequency of the second image pickup unit may be adjusted to be higher than a readout clock frequency of the first image pickup unit if the second image pickup unit is selected based on the component information of the component.

Thus, setting the readout clock frequency high only when the second image pickup unit with high resolution (a large number of pixels) is selected eliminates image readout delay in comparison with usage of the first image pickup unit, thereby eliminating tact delay.

Also in the above embodiment, when the image pickup conditions are adjusted, scan spacing of a component image picked up by the image pickup unit is set in accordance with the kind of the image pickup unit and the kind of the component based on the component information of the component, and when component recognition is performed based on the picked-up image, this picked-up component image is scanned based on the scan spacing of the component image set in accordance with the kind of the image pickup unit and the kind of the component, a component existing region in the component image is recognized, and then this recognized component existing region can be recognized as an image so as to enable posture recognition of the component.

Thus, performing image pickup and then performing recognition while culling out an electronic component existing region, and then finally performing image recognition of a recognized electronic component existing region shortens readout time and consequently shortens tact of the electronic component device in its entirety. Also, switching to the second image pickup unit may shorten readout time more effectively, resulting in implementing shortened tact.

Also in the above embodiment, when the component is illuminated with the illumination unit under the image pickup conditions, illumination direction of illumination light emitted to the component can be other than a direction orthogonal to any side of the component.

Regarding the above, a conventional illumination method of electronic components has had an issue as shown below. The issue will be described with reference toFIG. 16AandFIG. 16B.FIG. 16Ais a plan view showing an electronic component and a position of LED136for illuminating the electronic component as seen from a side of suction nozzle112, andFIG. 16Bis a front view thereof.

When illumination light is emitted in a direction orthogonal to each side14of the electronic component, the light may be reflected by illuminated side14and be picked up as noise in an image during image recognition, thereby causing misrecognition. This occurs particularly when the electronic component is a BGA, CSP, and the like, since pins and balls that are terminals of the component are close to mirrors. These components require image recognition with high precision, which causes an issue.

For such a conventional issue, setting an illumination angel of illumination to an electronic component to other than a direction orthogonal to one side of the electronic component prevents light from being reflected by the one side of the electronic component and being picked up as noise in an image during image recognition, thereby preventing misrecognition. This is particularly effective for image recognition of terminals of the component (pins and balls) with good precision in a case where the component is an electronic component having a large outline (BGA/CSP and the like).

Also in the above embodiment, when the component is illuminated with the illumination unit under the image pickup conditions, illumination light emitted from an illumination source is reflected by a reflection section upwardly toward a light diffusing plate disposed opposite to the image pickup unit with respect to the component, and the illumination light is diffused by the light diffusing plate, and when an image of the illuminated component is picked up by either one of the image pickup units under the image pickup conditions, an outline image of the component may be picked up with light diffused by the light diffusing plate.

Regarding the above, conventionally there has been an issue as shown below. Accordingly, description will be given of conventional illumination for illuminating a light diffusing plate on an opposite side of an image pickup unit with respect to a sucked electronic component, with reference toFIG. 17. InFIG. 17, an LED138has an illumination angle of, for example, 15° relative to a horizontal direction of a light diffusing plate. With light reflected and diffused by the light diffusing plate, an outline image of an electronic component is picked up by the image pickup unit for image recognition. In this case, since the illumination angle is small and therefore quantity of light diffused by the light diffusing plate is small, a larger quantity of light is desired for obtaining a clearer outline image of the electronic component with use of the image pickup unit.

Therefore, in order to improve illumination efficiency for obtaining an outline image of the electronic component, it is desirable to emit illumination light to the light diffusing plate at an angle as large as possible relative to the horizontal direction of the light diffusing plate. However, there is an issue that due to structure of a component mounting apparatus, a distance from the image pickup unit to the light diffusing plate cannot be increased.

For such a conventional issue, according to the above embodiment, in a case where illumination is emitted to the light diffusing plate for recognizing an outline of the electronic component with the image pickup unit, illumination light may be emitted to the light diffusing plate at a large angle relative to the horizontal direction of the light diffusing plate without changing a distance from the image pickup unit to the light diffusing plate, more particularly without increasing a distance from the image pickup unit to the light diffusing plate, which increases quantity of diffused light in the light diffusing plate, and improves illumination efficiency for obtaining an outline image of the electronic component, thereby implementing good image recognition.

Also in the above embodiment, when the image pickup conditions are adjusted, the second image pickup unit can be selected if, in component information of a component, the component is a lead component, or a C4 component such as a BAG or CSP, while the first image pickup unit can be selected if the component is a chip component.

Thus, an image pickup unit having optimum resolution for a component may be selected, which enables image pickup of small components to large components with almost the same image pickup quality while maintaining good resolution for image recognition.

Also in the above embodiment, when the image pickup conditions are adjusted, exposure time may be prolonged if, in component information of a component, electrode(s) of the component has difficulty in reflecting light like a plating electrode.

Thus, optimum exposure time may be set for the component, which enables image pickup of small components to large components with almost the same image pickup quality while maintaining good resolution for image recognition.

Also in the above embodiment, when image pickup conditions are adjusted, illumination light from an illumination source may be controlled so as to be emitted from almost right under a component if electrode(s) of the component is in a mirror state.

Thus, optimum illumination light for the component may be selected, which enables image pickup of small components to large components with almost the same image pickup quality while maintaining good resolution for image recognition.

It is noted that appropriate combinations of arbitrary embodiments among various embodiments stated above make it possible to implement an effect of each embodiment.

According to the present invention, even if the first image pickup unit and the second image pickup unit with high resolution are placed in parallel, the control section controls so as to eliminate difference in image quality due to difference in performance between the both image pickup units and kind of electronic component, enable seamless selection of the first and second image pickup units, and implement clear image pickup of large electronic components with resolution necessary for image recognition with use of the second image pickup unit.

Also, changing illuminance of illumination, kind of illumination, or a position of illumination to an electronic component based on information of the electronic component and through selection of two image pickup units makes it possible to eliminate difference in lightness of an image to be picked up due to difference in performance between both image pickup units and kind of the electronic component.

Also, changing exposure time of an image pickup unit selected by the control section based on information of the electronic component and through selection of the image pickup unit makes it possible to eliminate difference in lightness of the image to be picked up due to difference in performance between the image pickup units and the kind of the electronic component.

Also, controlling an image signal gain so as to be suited for image recognition makes it possible to eliminate difference in lightness of the image to be picked up due to difference in performance of both image pickup units and the kind of the component.

Also, setting a readout clock frequency high when the second image pickup unit with high resolution (a large number of pixels) is selected eliminates image readout delay in comparison with usage of the first image pickup unit, thereby eliminating tact delay.

Also, performing image pickup and performing recognition while culling out an electronic component existing region, and then finally performing image recognition of a recognized electronic component existing region shortens readout time and consequently shortens tact of the electronic component device in its entirety. Also, switching to the second image pickup unit can shorten readout time more effectively, resulting in implementing shortened tact.

Further, setting an illumination angle of illumination to an electronic component to other than a direction orthogonal to one side of the electronic component prevents light from being reflected by the one side of the electronic component and being picked up as noise in an image during image recognition, thereby preventing misrecognition. This is particularly effective for image recognition of terminals of the component (pins and balls) with good precision in a case where the component is an electronic component having a large outline (BGA/CSP and the like).

Furthermore, in a case where illumination is emitted to the light diffusing plate for recognizing an outline of the electronic component with the image pickup unit, illumination light may be emitted to the light diffusing plate at a large angle relative to a horizontal direction of the light diffusing plate without changing a distance from the image pickup unit to the light diffusing plate, which increases quantity of diffused light in the light diffusing plate, and improves illumination efficiency for obtaining an outline image of the electronic component, thereby implementing good image recognition.

According to the above, there are implemented optimum camera selection corresponding to a kind of a component and setting of scan spacing, which can provide an image with resolution corresponding to the component in a short period of time.