Patent Description:
Patent Literature <NUM> discloses an imaging unit in which an appropriate value of resolution for light of one or more light sources selected from multiple light sources used for imaging is obtained, light of one or more light sources is applied to a subject held by a holding member to image the subject with a camera, and the appropriate value of the resolution is used for processing an image obtained through the imaging. Patent Application <CIT> relates to a photographic system for capturing images of a subject being arranged in a casing. A photographic apparatus includes a housing for housing a subject and a photographing unit capturing the image of the subject. The subject is placed on a placement surface held by the subject moving unit. A drive unit moves the placement surface in the Z direction. A light source includes a bottom light source and an epi light source that irradiate light of different wavelengths on the subject. A controller controls the photographing unit to capture an image of the subject at a first wavelength and a second wavelength that is different from the first wavelength. Before image capture, a user operates the subject moving unit so as to determine a photographing distance SD. At least one image sensor and the subject are moved in the optical axis direction to correct for the lateral chromatic aberration of imaging lens. A storage means stores a table in which the relationship between the chromatic aberration of magnification and the optimum difference in image distance at each wavelength is stored. Patent Application <CIT> relates to aberration correction to correct chromatic aberration of magnification, based on stored correction data associated with correction levels and on predetermined combinations of aberration variation conditions. Patent Application <CIT> relates to image recording and reproduction, and in particular to chromatic aberration correction of an aperture amount of an iris and a lens image height of an object in an image pickup lens.

However, in the imaging unit disclosed in Patent Literature <NUM>, since the above appropriate value of the resolution is acquired by using an off-line imaging device different from a component mounter to which the imaging unit is attached, efforts and cost of manufacturing the off-line imaging device are increased.

Therefore, an object of the present disclosure is to provide a work machine capable of correcting chromatic aberration included in an image obtained by imaging a component without using a device separate from the work machine.

The present invention is defined by the features of the independent claim, with preferred embodiments being specified in the dependent claims.

According to the present disclosure, it is possible to correct chromatic aberration included in an image obtained by imaging a component without using a device separate from a work machine.

Embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

<FIG> illustrates component mounter <NUM> according to an embodiment of the present disclosure. Component mounter <NUM> is a device that executes component mounting work on circuit base material <NUM>. Component mounter <NUM> includes device main body <NUM>, base material conveyance/holding device <NUM>, component attachment device <NUM>, mark camera <NUM>, part camera <NUM>, component supply device <NUM>, bulk component supply device <NUM>, and control device <NUM> (refer to <FIG>). Examples of circuit base material <NUM> include a circuit board and a base material having a three-dimensional structure, and examples of the circuit board include a printed wiring board and a printed circuit board.

Device main body <NUM> includes frame portion <NUM> and beam portion <NUM> that is suspended on frame portion <NUM>. Base material conveyance/holding device <NUM> is disposed at the center of frame portion <NUM> in the front-rear direction, and has conveyance device <NUM> and clamp device <NUM>. Conveyance device <NUM> is a device that conveys circuit base material <NUM>, and clamp device <NUM> is a device that holds circuit base material <NUM>. Consequently, base material conveyance/holding device <NUM> conveys circuit base material <NUM> and holds circuit base material <NUM> fixedly at a predetermined position.

In the description below, a conveyance direction of circuit base material <NUM> will be referred to as an X direction, a horizontal direction perpendicular to that direction will be referred to as a Y direction, and a vertical direction will be referred to as a Z direction. That is, a width direction of component mounter <NUM> is the X direction, and a front-rear direction is the Y direction.

Component attachment device <NUM> is disposed in beam portion <NUM> and includes two work heads <NUM> and <NUM> and work head moving device <NUM>. As illustrated in <FIG>, suction nozzle <NUM> is provided on lower end face of each of work heads <NUM> and <NUM>, and suction nozzle <NUM> picks up and holds a component.

<FIG> is a view in which a lower end face of one work head, for example, work head <NUM> is viewed from the lower direction toward the upper direction. Lower end face <NUM> of work head <NUM> is formed in a disk shape as illustrated in <FIG>, and twenty-four holders 65a to 65x are disposed at equal intervals on an outer circumferential part thereof. Each of holders 65a to 65x holds one suction nozzle <NUM>. Respective holders <NUM> are denoted by the reference signs 65a to 65x in the clockwise direction from the first holder to the twenty-fourth holder. Similarly, each suction nozzle <NUM> is also denoted by the reference signs 66a to 66x in the clockwise direction from the first nozzle to the twenty-fourth nozzle. However, in <FIG>, the reference signs of holders <NUM> and suction nozzle <NUM> are explicitly indicated only as necessary for describing the present embodiment.

Entire lower end face <NUM> and each suction nozzle <NUM> each are configured to be rotated by a rotation device using a motor (not illustrated) as a driving source, and thus a position of a picked up and held component on the outer circumferential part and a direction at that position can be changed.

Reference mark M is attached to the center of lower end face <NUM>. Reference mark M is formed by a circle including four small circles. A method of using reference mark M will be described later.

Work head moving device <NUM> includes X-direction moving device <NUM>, Y-direction moving device <NUM>, and Z-direction moving device <NUM>. Two work heads <NUM> and <NUM> can be integrally moved to any position on frame portion <NUM> by X-direction moving device <NUM> and Y-direction moving device <NUM>. Work heads <NUM> and <NUM> are detachably attached to sliders <NUM> and <NUM>, and Z-direction moving device <NUM> individually moves sliders <NUM> and <NUM> in the up-down direction. That is, work heads <NUM> and <NUM> can be individually moved in the up-down direction by Z-direction moving device <NUM>.

Mark camera <NUM> is attached to slider <NUM> so as to face downward, and can be moved in the X direction, the Y direction, and the Z direction together with work head <NUM>. Consequently, mark camera <NUM> images any position on frame portion <NUM>. As illustrated in <FIG>, part camera <NUM> is disposed to face upward between base material conveyance/holding device <NUM> and component supply device <NUM> on frame portion <NUM>. Consequently, part camera <NUM> images components held by suction nozzles <NUM> of work heads <NUM> and <NUM>.

Specifically, as illustrated in <FIG>, part camera <NUM> includes lighting section <NUM> and imaging section <NUM>. Part camera <NUM> has an imaging range above part camera <NUM>, and captures an image of a component held by suction nozzles 66a to 66x from below to generate a captured image.

Lighting section <NUM> irradiates a component that is an imaging target with light. Lighting section <NUM> includes housing <NUM>, connecting portion <NUM>, epi-illuminating light source <NUM>, half mirror <NUM>, and multi-stage light source <NUM>.

Housing <NUM> is a bowl-shaped member of which upper and lower surfaces (bottom surfaces) are open in an octagonal shape. Housing <NUM> has a shape in which an opening on the upper surface is larger than an opening on the lower surface, and thus an internal space thereof tends to increase from the lower surface to the upper surface.

Connecting portion <NUM> is a cylindrical member that connects housing <NUM> to imaging section <NUM>.

Epi-illuminating light source <NUM> includes multiple LEDs <NUM>.

Half mirror <NUM> reflects light in the horizontal direction from LED <NUM> of epi-illuminating light source <NUM> upward. Half mirror <NUM> transmits light from the upper side toward imaging section <NUM>.

Multi-stage light source <NUM> includes upper-stage light source 147a, middle-stage light source 147b, and lower-stage light source 147c. Upper-stage light source 147a includes multiple LEDs 148a, middle-stage light source 147b includes multiple LEDs 148b, and lower-stage light source 147c includes multiple LEDs 148c. Each of LEDs 148a to 148c applies light in a direction inclined from optical axis 149a. An inclined angle of an irradiation direction of LEDs 148a to 148c with respect to optical axis 149a is maximum in LED 148a, and thus LED 148a applies light in a substantially horizontal direction. The inclined angle of LED 148c is smallest. Upper-stage light source 147a is referred to as a side illuminating light source because the light source applies light in a substantially horizontal direction, and middle-stage light source 147b is referred to as an inclined light source because the light source applies light in an obliquely up direction.

In the present embodiment, LED 148a of upper-stage light source 147a is a blue LED, and LED 148b of middle-stage light source 147b, LED 148c of lower-stage light source 147c, and LED <NUM> of epi-illuminating light source <NUM> are red LEDs.

Imaging section <NUM> generates a captured image based on the received light. Imaging section <NUM> includes an optical system such as a lens (not illustrated) and an imaging element (for example, a charge coupled device (CCD)).

When light emitted from epi-illuminating light source <NUM> and multi-stage light source <NUM> after being reflected by an imaging target component passes through half mirror <NUM> and reaches imaging section <NUM>, imaging section <NUM> receives the light to generate a captured image.

Component supply device <NUM> is disposed at a first end part of frame portion <NUM> in the front-rear direction. Component supply device <NUM> includes tray-type component supply device <NUM> and feeder-type component supply device <NUM> (refer to <FIG>). Tray-type component supply device <NUM> is a device that supplies a component in a state in which the component is placed on a tray. Feeder-type component supply device <NUM> is a device that supplies a component by using a tape feeder or a stick feeder (not illustrated).

Bulk component supply device <NUM> is disposed at a second end part of frame portion <NUM> in the front-rear direction. Bulk component supply device <NUM> is a device that aligns multiple components in a scattered state and supplies the components in an aligned state. That is, bulk component supply device <NUM> is a device that aligns multiple components in any posture and supplies the components in a predetermined posture. Electronic circuit components, solar cell constituent components, and power module constituent components, are examples of components that are supplied by component supply device <NUM> and bulk component supply device <NUM>. The electronic circuit components include a component having a lead, a component having no lead, and the like.

As illustrated in <FIG>, control device <NUM> includes controller <NUM>, multiple drive circuits <NUM>, and image processing device <NUM>. Multiple drive circuits <NUM> are connected to conveyance device <NUM>, clamp device <NUM>, work heads <NUM> and <NUM>, work head moving device <NUM>, tray-type component supply device <NUM>, feeder-type component supply device <NUM>, and bulk component supply device <NUM>. Controller <NUM> includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and the like, and is mainly a computer, and is connected to multiple drive circuits <NUM>. Consequently, operations of base material conveyance/holding device <NUM>, component attachment device <NUM>, component supply device <NUM>, and the like are controlled by controller <NUM>. Controller <NUM> is also connected to image processing device <NUM>. Image processing device <NUM> processes captured images acquired by mark camera <NUM> and part camera <NUM>, and controller <NUM> acquires various types of information from the captured images.

Next, chromatic aberration will be described. There are two types of chromatic aberration such as axial chromatic aberration and magnification chromatic aberration.

The axial chromatic aberration means a phenomenon in which light beams which are parallel to the optical axis do not form images at one point on the optical axis due to different refractive indexes resulting from different wavelengths. Specifically, as illustrated in <FIG>, an image is formed on the front side in a case of blue light, and on the back side in a case of red light.

On the other hand, the magnification chromatic aberration means a phenomenon in which light beams obliquely incident to the optical axis form images at different positions on an image plane, and thus a color deviation tends to occur more at radially outer circumferential parts of the images. Specifically, as illustrated in <FIG>, even if focal lengths are the same, distances from the center line of the lens are different between the blue light and the red light.

<FIG> illustrates a captured image obtained by part camera <NUM> capturing an image of lower end face <NUM> in <FIG>. The captured image in <FIG> represents an image obtained by combining an image captured through imaging when the red LED emits light (hereinafter, referred to as a "first captured image") and an image captured through imaging when the blue LED emits light (hereinafter, referred to as a "second captured image").

In <FIG>, circle Cr represents a circle formed by connecting centers of holders 65ar to 65xr included in the first captured image, that is, tips of suction nozzles 66ar to 66xr. On the other hand, circle Cb represents a circle formed by connecting centers of holders 65ab to 65xb included in the second captured image, that is, tips of suction nozzles 66ab to 66xb. The diameter of circle Cr and the diameter of circle Cb are different due to the influence of the magnification chromatic aberration. Since the magnification chromatic aberration occurs toward the lens center, as illustrated in <FIG>, in a case where lens center Ol and camera center Oc deviate with respect to each other, deviation occurs between the center of circle Cr and the center of circle Cb. Therefore, for example, a deviation width between the tip of the thirteenth suction nozzle 66mr in the first captured image and the tip of thirteenth suction nozzle 66mb in the second captured image is larger than a deviation width between the tip of first suction nozzle 66ar in the first captured image and the tip of first suction nozzle 66ab in the second captured image.

Conversely, in a case where lens center Ol coincides with camera center Oc, there is no deviation between the center of circle Cr and the center of circle Cb. However, since lens center Ol is not visible, lens center Ol is not aligned with camera center Oc when part camera <NUM> is assembled. Therefore, in many cameras, including part camera <NUM>, there is deviation between the lens center and the camera center.

Although the influence of such chromatic aberration can be eliminated by lens design, in the present embodiment, the influence of chromatic aberration is not eliminated by the lens design but is eliminated by calibration.

<FIG> illustrates a procedure of a calibration process executed by controller <NUM>. Hereinafter, in descriptions of the procedures of each process, a step is denoted by "S".

The calibration process is executed when it is necessary to remove the influence of the chromatic aberration, specifically, when work heads <NUM> and <NUM> are replaced with other work heads, or when the influence of the chromatic aberration becomes different due to aging or the like.

When the calibration process is started, first, controller <NUM> commands work head moving device <NUM> via drive circuit <NUM> to move work head <NUM> to imaging range <NUM> (refer to <FIG>) (S10). Although the calibration process is performed not only on work head <NUM> but also on work head <NUM>, for convenience of description, it is assumed that the calibration process is performed only on work head <NUM> in the present embodiment.

Next, controller <NUM> determines a color of irradiation light from lighting section <NUM> (S12). In the present embodiment, colors of the irradiation light are two colors such as red and blue, but the present invention is not limited to this, and may be three colors in addition to the case where red light and blue light are applied simultaneously, or may be four colors or more as long as lighting section <NUM> can apply irradiation light of four or more colors.

Next, in step S14, controller <NUM> commands lighting section <NUM> to irradiate lower end face <NUM> of work head <NUM> with the irradiation light of the determined color.

Next, controller <NUM> commands part camera <NUM> to capture an image (S16). In response to this, part camera <NUM> captures an image of lower end face <NUM> of work head <NUM> located in imaging range <NUM>, and outputs the captured image to image processing device <NUM>.

Controller <NUM> reads the captured image from image processing device <NUM>, and temporarily stores the captured image in the RAM, for example (S18).

Next, in step S20, controller <NUM> determines whether or not there is irradiation light of a color that has not yet applied. When red light is first applied and blue light is applied next as the irradiation light, since the blue irradiation light has not yet applied, it is determined in the determination in S20 that there is irradiation light of a color that has not yet applied (S20: NO), and controller <NUM> returns the processing to S12.

Controller <NUM> executes the processes in S12 to S18 described above on the blue irradiation light. After this process is executed, it is determined in the determination in S20 that there is no irradiation light of a color that has not yet applied (S20: YES), and controller <NUM> causes the process to proceed to the next S22.

In S22, the center and a diameter of a circle passing through predetermined three points are calculated for each captured image, that is, the first and second captured images. Here, the predetermined three points are, in the present embodiment, for example, points in the first and second captured images, respectively corresponding to the tip of first suction nozzle 66a, the tip of thirteenth suction nozzle <NUM>, and the tip of nineteenth suction nozzle <NUM>. The reason why three points are taken is to satisfy the minimum condition that one circle is determined. This is because one circle is not determined by two points, and one circle is determined by four or more points, but the processing time for determining one circle is longer than in the case where three points are taken. However, the three points to be adopted may be any three of the tips of twenty-four suction nozzles 66a to 66x. When coordinates of predetermined three points included in each of the first and second captured images are known, the center and the diameter of each circle passing through the three points can be easily calculated from the coordinates according to a well-known method, and thus a description of the calculation method will be omitted.

Next, controller <NUM> calculates lens center Ol based on the center and the diameter of each circle calculated in the first and second captured images (S24). Specifically, controller <NUM> calculates a movement direction and a movement amount of the center of each circle and a reduction amount of the diameter, calculates a position at which the center of the circle moves when the diameter converges to "<NUM>", and sets this position as lens center Ol.

Next, controller <NUM> calculates a difference between calculated lens center Ol and camera center Oc, and temporarily stores the difference in, for example, the RAM (S26).

Next, controller <NUM> converts each circle calculated in the first and second captured images into each circle at lens center Ol based on the stored difference, and calculates a diameter of each circle after the conversion (S28). The reason why conversion into each circle at lens center Ol in this manner is that, as described above, the magnification chromatic aberration occurs toward lens center Ol, whereas each circle calculated in S22 is a circle at camera center Oc, and the influence of the magnification chromatic aberration cannot be accurately calculated with the circle at camera center Oc.

Specifically, in the calculation process in S28, the stored difference is denoted by (Ax, Ay), coordinates of the respective tips of first, thirteenth, and nineteenth suction nozzles 66ar, 66mr, and 66sr included in the first captured image are denoted by (Rx1, Ry1), (Rx2, Ry2), and (Rx3, Ry3), and coordinates of the respective tips of first, thirteenth, and nineteenth suction nozzles 66ab, 66mb, and 66sb included in the second captured image are denoted (Bx1, By1), (Bx2, By2), and (Bx3, By3). Since these coordinates are coordinates at camera center Oc, controller <NUM> converts the coordinates into coordinates at lens center Ol. That is, controller <NUM> calculates coordinates (Rx1-Ax, Ry1-Ay), (Rx2-Ax, Ry2-Ay), and (Rx3-Ax, Ry3-Ay) for the coordinates (Rx1, Ry1), (Rx2, Ry2), and (Rx3, Ry3) in the first captured image, and calculates coordinates (Bx1-Ax, By1-Ay), (Bx2-Ax, By2-Ay), and (Bx3-Ax, By3-Ay) for the coordinates (Bx1, By1), (Bx2, By2), and (Bx3, By3) in the second captured image. Controller <NUM> determines each circle passing through the three points after the conversion, and calculates a diameter of each circle.

Next, controller <NUM> calculates, with predetermined one color of the irradiation light as a reference color, a value of a ratio of the diameter of the circle of another color to the diameter of the circle of the reference color (S30). For example, in a case where the reference color is red, controller <NUM> calculates the diameter of the circle after the conversion from camera center Oc into lens center Ol in the second captured image/the diameter of the circle after the conversion from camera center Oc into lens center Ol in the first captured image.

Next, controller <NUM> stores the calculated value of the ratio as a coefficient value in correlation with the irradiation light (S32). In the present embodiment, since the value of the ratio is the diameter of the circle after conversion in the second captured image, that is, the captured image with the blue irradiation light/the diameter of the circle after conversion in the first captured image, that is, the captured image with the red irradiation light, the calculated value of the ratio, that is, the coefficient value is stored in correlation with blue. However, since the coefficient value is used when an electronic component (hereinafter abbreviated to "component") is mounted on a circuit base material after the calibration process is completed before the next calibration process is executed, it is preferable to store the coefficient value in a memory in which storage of the coefficient value is maintained even in a case where the supply of power to control device <NUM> is stopped.

Next, controller <NUM> commands work head moving device <NUM> via drive circuit <NUM> to move work head <NUM> such that reference mark M (refer to <FIG>) is located at one of the four corners of imaging range <NUM> (S34).

Next, controller <NUM> commands lighting section <NUM> to irradiate lower end face <NUM> of work head <NUM> with the irradiation light of the reference color (S36).

Since the subsequent processes in S38 and S40 are respectively the same as the processes in S16 and S18, descriptions thereof will be omitted.

Controller <NUM> determines whether or not a captured image of one corner that is point-symmetrical to one corner where reference mark M is located with respect to the center of imaging range <NUM> in imaging range <NUM> has been stored (S42). In this determination, in a case where it is determined that captured images of the two corners have not yet been stored (S42: NO), controller <NUM> returns the process to S34.

Controller <NUM> locates reference mark M at another corner of imaging range <NUM> (S34), and then executes the processes in steps S36 to S40. After these processes are executed, in the determination in S42, it is determined that the captured images of the two corners have been stored (S42: YES), and controller <NUM> causes the process to proceed to the next S44.

In S44, controller <NUM> calculates and stores a resolution at the reference color based on the stored two captured images. Specifically, controller <NUM> acquires coordinates of the center of reference mark M for each captured image, and calculates a length of a line segment having each image as an end point. Controller <NUM> calculates the calculated length of the line segment/the number of pixels included in the line segment, and stores the calculation result as a resolution at the reference color, that is, the resolution at red in the present embodiment. Since the resolution at the reference color is also used when a component is mounted on a circuit base material after the calibration process is completed and before the next calibration process is executed, similarly to the coefficient value, it is preferable to store the resolution in the memory in which storage of the coefficient value is maintained even in a case where the supply of power to control device <NUM> is stopped.

When the process in S44 is completed, controller <NUM> finishes the calibration process.

Next, it will be described how to use the coefficient value and the resolution in the reference color stored through the calibration process when a component is mounted on a circuit base material.

When a component is mounted on the circuit base material, as described above, a mounting target component is held by suction nozzle <NUM>, and the held component is imaged by part camera <NUM>. By performing image processing on the captured image obtained by part camera <NUM>, controller <NUM> recognizes a position of the component with respect to the center of suction nozzle <NUM> from the image of the component included in the captured image. The position of the center of suction nozzle <NUM> in the captured image is known.

In theory, the center of suction nozzle <NUM> coincides with a predetermined pickup position of the component (typically, the center of the component). However, due to deviation or the like in a component supply position, the component is picked up in a state in which the center of suction nozzle <NUM> and the predetermined pickup position of the component deviate relative to each other. Therefore, controller <NUM> recognizes a deviation amount between the predetermined pickup position of the component and the center of suction nozzle <NUM>. controller <NUM> controls drive circuit <NUM> such that the component is disposed immediately above a designated position of the circuit base material in consideration of the recognized deviation amount. Here, a resolution of the captured image obtained by part camera <NUM> differs depending on a color of the irradiation light. Specifically, an actual distance corresponding to one pixel differs depending on a color of the irradiation light. Thus, controller <NUM> converts the recognized deviation amount into an actual distance by using the resolution corresponding to the color of the irradiation light, and controls drive circuit <NUM>.

In a case where the color of the irradiation light is the reference color, controller <NUM> converts the recognized deviation amount into an actual distance by using the resolution at the reference color. On the other hand, in a case where the color of the irradiation light is different from the reference color, controller <NUM> converts the recognized deviation amount into an actual distance by using a resolution obtained by multiplying the resolution at the reference color by the coefficient value stored in correlation with the color of the irradiation light.

As described above, component mounter <NUM> of the present embodiment includes part camera <NUM>, work heads <NUM> and <NUM> having suction nozzles <NUM>, X-direction moving device <NUM> and Y-direction moving device <NUM> that move work heads <NUM> and <NUM> at least in the horizontal direction, lighting section <NUM> capable of applying light having different wavelengths from multiple light sources toward suction nozzles <NUM>, and controller <NUM>.

Controller <NUM> has imaging command section <NUM> that commands part camera <NUM> to apply light having different wavelengths to suction nozzle <NUM> to image suction nozzle <NUM>, first calculation section <NUM> that calculates, based on any one captured image among captured images obtained by imaging command section <NUM> for respective light beams having different wavelengths, a resolution of the captured image, second calculation section <NUM> that calculates the lens center of part camera <NUM> based on the captured images for the respective light beams having different wavelengths, and storage section <NUM> that stores a difference between the lens center calculated by second calculation section <NUM> and the camera center of part camera <NUM> as a unique value of part camera <NUM>.

As described above, in component mounter <NUM> of the present embodiment, it is possible to correct the chromatic aberration included in a captured image of a component without using another device different from component mounter <NUM>.

Incidentally, in the present embodiment, component mounter <NUM> is an example of a "work machine". Suction nozzle <NUM> is an example of a "component holder". Work heads <NUM> and <NUM> are examples of "holding heads". X-direction moving device <NUM>, Y-direction moving device <NUM> and Z-direction moving device <NUM> are examples of "moving device". Part camera <NUM> is an example of an "imaging device". Controller <NUM> is an example of a "control device".

Controller <NUM> further includes third calculation section <NUM> that calculates coefficient values for calculating resolutions of captured images other than a captured image used as a resolution calculation basis among the captured images for respective light beams having different wavelengths, based on the unique value stored in storage section <NUM>.

Consequently, since resolutions of the captured images other than the captured image used as a resolution calculation basis are obtained by merely multiplying the coefficient value calculated by the third calculation section <NUM> by the resolution of the captured image used as a resolution calculation basis, a resolution of a captured image for one light beam having a wavelength may be calculated even if there are multiple captured images for light beams having different wavelengths. Therefore, a calculation process can be simplified.

Controller <NUM> further includes fourth calculation section <NUM> that multiplies the coefficient value calculated by third calculation section <NUM> by the resolution calculated by first calculation section <NUM> to calculate the resolutions of the captured images other than the captured image used as a resolution calculation basis, and correction section <NUM> that corrects a corresponding captured image based on the resolutions calculated by first and fourth calculation sections <NUM> and <NUM>.

Suction nozzle <NUM> includes three or more suction nozzles 66a to 66x, suction nozzles 66a to 66x are arranged at equal intervals on the outer circumferential part of lower end face <NUM> of work heads <NUM> and <NUM>, and second calculation section <NUM> calculates the lens center of part camera <NUM> based on at least three suction nozzles 66ar, 66mr, 66sr, 66ab, 66mb, and 66sb among suction nozzles 66ar to 66xr and 66ab to 66xb included in the captured images for light beams having different wavelengths.

Consequently, since the lens center of part camera <NUM> can be calculated by detecting at least three points for each captured image for respective light beams having different wavelengths, the image processing can be simplified, and the calculation processing can also be simplified.

Second calculation section <NUM> calculates centers and diameters of circles Cr and Cb passing through each of the tips of at least three suction nozzles 66ar, 66mr, 66sr, 66ab, 66mb, and 66sb for each captured image for respective light beams having different wavelengths, and calculates lens center Ol of part camera <NUM> based on the calculated centers and diameters of respective circles Cr and Cb.

Third calculation section <NUM> converts each of the tips of at least three suction nozzles 66ar, 66mr, 66sr, 66ab, 66mb, and 66sb from camera center Oc into lens center Ol based on the unique value stored in storage section <NUM>, calculates a diameter of each circle passing through respective tips of at least three suction nozzles after conversion, and calculates the coefficient value based on the calculated diameter of each circle for each captured image of respective light beams having different wavelengths.

The present invention is not limited to the above embodiment, and various modifications can be made within the scope of the claims.

Claim 1:
A work machine (<NUM>) comprising:
an imaging device (<NUM>);
a holding head (<NUM>, <NUM>) having a component holder (<NUM>);
a moving device (<NUM>, <NUM>, <NUM>) configured to move the holding head in at least a horizontal direction;
a lighting device (<NUM>) configured to apply irradiation light having different wavelengths from multiple light sources (<NUM>) toward the component holder; and
a control device (<NUM>), wherein
the control device includes
an imaging command section (<NUM>) configured to command the imaging device to irradiate the component holder with light having different wavelengths to capture an image of the component holder,
a first calculation section (<NUM>) configured to calculate, based on any one captured image among captured images obtained by the imaging command section for respective light beams having different wavelengths, a number of pixels included in a line segment as a resolution of the captured image for each respective light beam, wherein a length of the line segment corresponds to the actual distance covered from a camera center of the imaging device to an end point of the captured image,
a second calculation section (<NUM>) configured to calculate a lens center of the imaging device based on the captured images for the respective light beams having different wavelengths, and
a storage section (<NUM>) configured to store a difference between the lens center calculated by the second calculation section and the camera center of the imaging device as a unique value of the imaging device,
characterized in that
the component holder includes three or more component holders,
the three or more component holders are arranged at equal intervals on an outer circumferential part of a lower end face of the holding head, and
the second calculation section is configured to calculate the lens center of the imaging device based on at least three component holders among the three or more component holders included in each of the captured images for the respective light beams having different wavelengths.