Image capture device for object and component mounting device equipped with the same

Abstract

To allow an imaging apparatus which images a moving object to acquire an image of the object with small variance in contrast even when the object passes through an imaging area of an imaging camera at a different speed.SOLUTION: A component mounting device 1 includes a component recognition camera 9 which picks up an image of a component E passing through an imaging area CA, and a control part 20 which controls the imaging operation of the component recognition camera 9. The control part 20 includes a speed acquisition part 26 which acquires information on a passing speed of the component E passing through the imaging area CA, and an exposure control part 24 which varies an exposure time of the component recognition camera 9 according to the passing speed. The exposure control part 24 sets a second exposure time for which the component E at a passing speed V2 is imaged to shorter than a first exposure time for which the component E at a passing speed V1 (V1<V2) is imaged.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to an imaging device for imaging various objects such as electronic components, and a component mounting apparatus equipped with the same. [Background technology]

[0002] A component mounting device that mounts electronic components on a board includes a mounting head having a suction nozzle. The suction nozzle picks up and holds the electronic component at a component supply position, and transfers it above the board while mounting it on the board. The suction nozzle holding the electronic component is imaged by a component recognition camera arranged below the suction nozzle. The suction state of the electronic component by the suction nozzle is determined based on the image acquired by the image acquisition. Generally, in order to improve takt time, a flying vision method is often adopted in which the mounting head is moved while the image is acquired (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-287199 A Summary of the Invention [Problem to be solved by the invention]

[0004] Compared to the stop vision method in which the mounting head is stopped temporarily above the component recognition camera to capture the image, the contrast of the image of the electronic component obtained by the flying vision method is lower. In other words, since the electronic component moves during the exposure time of the component recognition camera, the electronic component in the captured image is blurred. In addition, since the moving speed of the mounting head is not constant, the amount of blur of the electronic component image also varies. In other words, the contrast (image quality) of the electronic component in the image is not constant, which may hinder accurate determination of the component suction state.

[0005] An object of the present invention is to provide an imaging device that images a moving object and is capable of acquiring images of the object with little variation in image contrast even if the speed at which the object passes through the imaging area of ​​the imaging camera varies, and a component mounting device equipped with the imaging device. [Means for solving the problem]

[0006] According to one aspect of the present invention, an imaging device for an object includes an imaging camera having a predetermined imaging area and including an imaging element having a plurality of pixels for capturing an image of an object passing through the imaging area, and a control unit for controlling an imaging operation of the imaging camera, the control unit including a speed acquisition unit for acquiring information on a passing speed of the object passing through the imaging area, and an exposure control unit for changing an exposure time of the imaging camera in accordance with the passing speed, Number of pixels to capture The special 3 pixels The speed of the passage is determined in advance. The image is captured at the specific three pixels. And the center position of the image is 3 specific pixels The exposure time is determined so that the central pixel of the image is the pixel of interest.

[0007] When capturing an image of a moving object, the object inevitably blurs in the captured image. The amount of image blur varies depending on the speed at which the object passes through the imaging area. With the imaging device described above, the exposure time of the imaging camera is changed according to the speed at which the object passes through the imaging area. This makes it possible to suppress the variation in the amount of image blur between objects with different passing speeds and to make the contrast of the captured image of the object as uniform as possible.

[0008] In the above-mentioned object imaging device, when there is a first imaging object whose passing speed is a first speed and a second imaging object whose passing speed is a second speed faster than the first speed, it is desirable for the exposure control unit to set the second exposure time when imaging the second imaging object to be shorter than the first exposure time when imaging the first imaging object.

[0009] When the exposure time is constant, the amount of image blur increases as the passing speed of the image capturing object increases. According to the image capturing device, when capturing an image of a second image capturing object passing at a second speed faster than the first speed of the first image capturing object, a second exposure time shorter than the first exposure time of the first image capturing object is set. Therefore, the variation in the amount of image blur can be appropriately suppressed.

[0010] In the above-mentioned object imaging device, it is desirable that the exposure control unit sets the first exposure time and the second exposure time so that the distance that the first imaging object moves in the imaging area within the first exposure time is equal to the distance that the second imaging object moves in the imaging area within the second exposure time.

[0011] According to this imaging device, even though the first and second objects pass through the imaging area at different speeds, the image blur amount in the images acquired for these objects can be made constant. Therefore, the image quality of the objects can be made constant, and the shape, surface condition, attitude, etc. of the objects can be accurately determined based on the acquired images.

[0012] The control unit further includes a clock generating unit that generates a counter clock, and a clock counting unit that is capable of counting the number of occurrences of the counter clock within a specific period, and the speed acquisition unit acquires a count value of the counter clock within a period required for the image capture object to move a unit distance immediately before the image capture, and the exposure control unit calculates a value based on the count value of the counter clock. A fixed value corresponding to the number of pixels regulated It is preferable to set a time corresponding to a value obtained by multiplying the above-mentioned exposure time by a coefficient set in the above-mentioned formula.

[0013] According to this imaging device, the moving speed of the object just before imaging is calculated from the count value of the counter clock, and the exposure time is set based on the value obtained by multiplying this count value by a fixed coefficient. Therefore, the exposure time can be automatically set to a short time when the moving speed of the object is fast and to a long time when the moving speed is slow.

[0014] In the above-mentioned imaging device for an object, the object to be imaged passes through the imaging area by a moving body that moves while holding the object to be imaged, and the distance traveled by the moving body is measured by a distance measuring unit, and the clock counting unit can be configured to count the number of occurrences of the counter clock within a period in which the distance measuring unit detects the movement of a unit distance of the moving body.

[0015] According to this imaging device, the moving speed of the imaging object can be obtained by a simple and reliable method of counting the number of generated counter clocks.

[0016] In the above-mentioned imaging device for an object, it is preferable that the control unit further includes an approach angle acquisition unit that acquires information on an approach angle of the imaging object with respect to the imaging area, and the velocity acquisition unit corrects the passing velocity of the imaging object acquired in one axial direction to a passing velocity along the approach angle.

[0017] Alternatively, it is desirable that the speed acquisition unit acquires, as information on the passing speed of the imaged object, information on a first passing speed in a first axial direction and information on a second passing speed in a second axial direction perpendicular to the first axial direction within the plane of the imaged image, and derives the passing speed along the movement direction of the imaged object based on the first passing speed and the second passing speed.

[0018] According to these imaging devices, even if the speed acquisition unit is configured to be unable to acquire information on the passing speed in only one axial direction, it is possible to accurately grasp the passing speed of the imaging target moving in a direction tilted relative to the one axial direction, and therefore it is possible to set an appropriate exposure time according to the passing speed.

[0019] A component mounting apparatus according to another aspect of the present invention comprises a mounting head having a holding portion for holding a component, a moving mechanism for moving the mounting head, and an imaging device for the above-mentioned object, wherein the moving mechanism moves the mounting head so that the holding portion holding the component passes through the imaging area, and the control unit causes the imaging camera to perform the imaging operation when the holding portion passes through the imaging area.

[0020] According to this component mounting device, the exposure time of the imaging camera is changed according to the passing speed of the electronic component held by the holder and passing through the imaging area. Therefore, it is possible to suppress the variation in the amount of image blur between the electronic components passing at different passing speeds. Therefore, it is possible to make the contrast of the image of the electronic component as uniform as possible, and it is possible to accurately determine the type, posture, etc. of the component held by the holder. Effect of the Invention

[0021] According to the present invention, it is possible to provide an imaging device that images a moving object, which is capable of acquiring images of the object with little variation in image contrast even if the speed at which the object passes through the imaging area of ​​the imaging camera varies, and a component mounting device equipped with the imaging device. [Brief description of the drawings]

[0022] [Figure 1] FIG. 1 is a plan view showing a schematic configuration of a component mounting apparatus to which an object imaging device according to the present invention is applied. [Diagram 2] FIG. 2 is a block diagram showing the electrical configuration of the component mounting apparatus. [Diagram 3] FIG. 3 is a schematic diagram showing the imaging of a component using the flying vision method. [Figure 4] 4(A) to 4(C) are diagrams showing schematic views of component imaging in a comparative example in which the exposure time is constant. [Diagram 5] FIG. 5 is a diagram showing an image acquired by imaging in a comparative example. [Figure 6]6(A) and (B) are diagrams showing schematic diagrams of component imaging modes in which the exposure time is changed according to the first embodiment of the present invention. [Figure 7] FIG. 7 is a diagram showing an image acquired by imaging in the first embodiment. [Figure 8] FIG. 8 is a time chart showing the imaging process of the first embodiment. [Figure 9] 9A and 9B are diagrams for explaining problems that arise when an image capture object approaches an image capture area from an oblique direction. [Figure 10] 10A and 10B are diagrams showing component imaging according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In this embodiment, an example is shown in which an imaging device for an object according to the present invention is applied to a component mounting device. Therefore, the imaging object in this embodiment is a small piece-like electronic component such as an IC, a transistor, a capacitor, or a packaged electronic component (hereinafter simply referred to as a component). This is only one example, and the imaging object may be various workpieces other than components (metal or resin articles or products, food, fruit, natural products, etc.).

[0024] [Overall structure of component mounting equipment] Fig. 1 is a plan view showing a schematic configuration of a component mounting apparatus 1. The component mounting apparatus 1 is an apparatus that mounts various components on a substrate P to produce a circuit board. The component mounting apparatus 1 includes an apparatus main body 1A, a moving frame 2, a conveyor 3, a component supply unit 4, a tape feeder 5, a head unit 6 (mounting head), a first driving mechanism 7, and a second driving mechanism 8 (moving mechanism). The component mounting apparatus 1 also includes a component recognition camera 9 (imaging camera) and a substrate recognition camera 63 as imaging devices. The X direction in Fig. 1 is the transport direction of the substrate P, and the Y direction is the direction perpendicular to the X direction in the horizontal plane.

[0025] The device body 1A is a structure in which the various components of the component mounting device 1 are arranged, and is formed in a substantially rectangular shape when viewed from above. The moving frame 2 extends in the X direction and is supported by the device body 1A so as to be movable in the Y direction. The conveyor 3 carries the board P into the device body 1A from the -X side, transports it leftward to a predetermined work position (the position of the board P shown in FIG. 1) and stops it once. At this work position, components are mounted on the board P. After the mounting work, the conveyor 3 transports the board P to the +X side and takes it out of the device body 1A.

[0026] The component supply units 4 supply electronic components to be mounted on the board P. The component supply units 4 are arranged in two locations each in the +Y side and -Y side areas of the device main body 1A, sandwiching the conveyor 3. Each component supply unit 4 is equipped with tape feeders 5 arranged in the X direction. Each tape feeder 5 is a feeder that supplies components using a component storage tape as a carrier. The tape feeder 5 intermittently pays out the component storage tape from a reel on which the tape is wound, and supplies the components to a predetermined component removal position.

[0027] The head unit 6 performs an operation of picking up components from the component supply unit 4 and mounting them on the substrate P. The head unit 6 is mounted on a moving frame 2 and is movable in the XY directions above the work position as described below. The head unit 6 includes a head main body 61 and a plurality of nozzles 62 (holding portions) that hold the components.

[0028] The head body 61 includes a Z-axis servo motor 12 that moves the nozzle 62 up and down in the Z direction (a direction perpendicular to the X and Y directions), and an R-axis servo motor 13 (FIG. 2) that rotates the nozzle 62 around the axis of the nozzle 62 (around the Z axis). In addition, the head body 61 is equipped with a suction mechanism that makes the nozzle 62 perform a component suction operation. The multiple nozzles 62 are attached to the lower end of a shaft 611 (FIG. 3) that can be raised and lowered relative to the head body 61, and are arranged in a row. The nozzle 62 has a suction hole at the tip (lower end) that sucks up the component. The nozzle 62 moves up and down in the Z direction to suck up the component from the tape feeder 5 at the component removal position, and the suction is released at a predetermined position on the board P, thereby performing a mounting operation to mount the component on the board P.

[0029] The first drive mechanism 7 is disposed at the ends of the +X side and -X side of the device main body 1A. The first drive mechanism 7 is a mechanism for moving the moving frame 2 in the Y direction. The first drive mechanism 7 is configured to include a Y-axis servo motor 11 (FIG. 2), a ball screw shaft that extends in the Y direction and is connected to the Y-axis servo motor 11, and a ball nut that is disposed on the moving frame 2 and screws into the ball screw shaft. The first drive mechanism 7 configured in this way moves the moving frame 2 in the Y direction by the ball nut moving back and forth along the ball screw shaft as the ball screw shaft is rotationally driven by the Y-axis servo motor 11.

[0030] The second drive mechanism 8 is disposed on the moving frame 2. The second drive mechanism 8 is a moving mechanism that moves the head unit 6 in the X direction along the moving frame 2. The second drive mechanism 8 includes an X-axis servo motor 10 (FIG. 2), a ball screw shaft that extends in the X direction and is connected to the X-axis servo motor 10, and a ball nut that is disposed on the head unit 6 and screws into the ball screw shaft. The second drive mechanism 8 thus configured moves the head unit 6 in the X direction by the ball nut moving forward and backward along the ball screw shaft as the ball screw shaft is rotated and driven by the X-axis servo motor 10. As described above, the head unit 6 can be moved in the X and Y directions by the first and second drive mechanisms 7 and 8.

[0031] The component recognition camera 9 is incorporated in the device main body 1A, and is a camera having a predetermined imaging area above the device main body 1A. The component recognition camera 9 captures an image of the component sucked by the nozzle 62 of the head unit 6 from the bottom side. On the image data obtained by the imaging, the amount of deviation between the center position of the component and the reference position of the nozzle 62 (positional deviation in the X-axis and Y-axis directions) and the amount of rotational deviation in the R-axis direction are detected, and position correction according to these deviations is performed when the component is mounted.

[0032] The board recognition camera 63 is mounted on the head main body 61 of the head unit 6. The board recognition camera 63 moves together with the head unit 6 and captures images of various marks marked on the upper surface of the board P from above in order to identify the type of board P and to position the board P. The board recognition camera 63 also captures images of the components exposed from the component storage tape at the component removal position, and obtains images for determining whether or not there is an abnormality in the storage orientation of the components in the pockets.

[0033] [Electrical configuration of component mounting device] 2 is a block diagram showing an electrical configuration of the component mounting apparatus 1. The component mounting apparatus 1 includes an illumination unit 14, an encoder 15 (distance measurement unit), an input unit 16, a display unit 17, a timing generator 18, and a control unit 20, in addition to the above-mentioned X-axis servo motor 10, Y-axis servo motor 11, Z-axis servo motor 12, R-axis servo motor 13, component recognition camera 9, and board recognition camera 63.

[0034] The illumination unit 14 is composed of an LED light source or the like, and generates the required illumination light when imaging is performed by the component recognition camera 9 and the board recognition camera 63. The encoder 15 detects the amount of movement of the head unit 6 in the X direction. That is, the encoder 15 measures the movement distance of the head unit 6 (moving body) moved in the X direction along the moving frame 2 by the second driving mechanism 8, using a linear scale or the like. The detection data from the encoder 15 is used to derive the movement speed of the head unit 6 (nozzle 62 holding a component).

[0035] The input unit 16 is made up of a keyboard, a touch panel, etc., and accepts input of various operation information, control conditions, setting data, component information, etc. for the component mounting apparatus 1. For example, the input unit 16 accepts setting input of the moving speed, moving direction, etc. of the head unit 6. The display unit 17 is made up of a display device, and performs required display related to the component mounting apparatus 1.

[0036] The timing generator 18 generates a timing signal that serves as a reference for various timing controls executed by the control unit 20. The timing generator 18 includes a clock generating unit 181 and a clock counting unit 182. The clock generating unit 181 generates a counter clock of a predetermined frequency (e.g., 80 MHz). The clock counting unit 182 counts the number of occurrences of the counter clock within a specific period.

[0037] For example, the clock counting unit 182 counts the number of counter clocks generated by the clock generating unit 181 during the period of movement of a unit distance of the head unit 6. The unit distance can be determined when the scale pulses generated by the encoder 15 for each unit of the linear scale passing by the encoder 15 reach a certain number. The counted value of the number of clocks depends on the moving speed of the head unit 6. In other words, the smaller the number of clocks, the faster the head unit 6 is moving in the X direction.

[0038] The control unit 20 is made up of a microcomputer and controls, based on a predetermined program, each unit included in the component mounting apparatus 1. The control unit 20 operates to be functionally equipped with an overall control unit 21, an axis control unit 22, an imaging control unit 23, an image processing unit 25, a speed acquisition unit 26, and an approach angle acquisition unit 27 by executing the program.

[0039] The overall control unit 21 comprehensively controls various operations of the component mounting apparatus 1. For example, the overall control unit 21 comprehensively controls the transport operation of the substrate P by the conveyor 3, the component supply operation by the component supply unit 4, the component mounting operation by the head unit 6, and the like.

[0040] The axis control unit 22 moves the head unit 6 in the X and Y directions by controlling the driving of the X-axis servo motor 10 and the Y-axis servo motor 11. This controls the X and Y direction positions of the head main body 61 (nozzle 62) mounted on the head unit 6 and the board recognition camera 63. The axis control unit 22 also controls the lifting and lowering of the nozzle 62 and the rotation around the Z axis by controlling the driving of the Z-axis servo motor 12 and the R-axis servo motor 13. This allows the component picked up by the nozzle 62 to be mounted on the board P and the rotational position of the component to be adjusted.

[0041] The imaging control unit 23 controls the imaging operations of the component recognition camera 9 and the board recognition camera 63. Specifically, the imaging control unit 23 controls the illumination unit 14, while controlling the operation of causing the component recognition camera 9 to image the component sucked by the nozzle 62, and the operation of causing the board recognition camera 63 to image the fiducial mark of the board P. The imaging control unit 23 includes an exposure control unit 24. The exposure control unit 24 controls the exposure time, the amount of illumination light, and the like during the imaging operation. In this embodiment, the exposure control unit 24 changes the exposure time of the component recognition camera 9 depending on the passing speed at which the nozzle 62 holding the component passes through the imaging area of ​​the component recognition camera 9. This point will be described in detail later.

[0042] The image processing unit 25 performs image processing such as edge detection processing for shape recognition on the image data acquired by the component recognition camera 9 and the board recognition camera 63. The image processing unit 25 performs image processing on the image acquired by the component recognition camera 9 to recognize whether or not the component is being picked up by the nozzle 62 and the pickup attitude. The image processing unit 25 also performs image processing on the image acquired by the board recognition camera 63 to recognize the fiducial mark.

[0043] The speed acquisition unit 26 acquires information on the passing speed at which the nozzle 62 passes through the imaging area of ​​the component recognition camera 9. The speed acquisition unit 26 acquires the count value of the counter clock by the clock counting unit 182 as the passing speed information (described in detail below with reference to FIG. 8). The approach angle acquisition unit 27 acquires information on the approach angle of the nozzle 62 with respect to the imaging area of ​​the component recognition camera 9 (described in detail below with reference to FIG. 10).

[0044] [About the Flying Vision System] 3 is a schematic diagram showing how the component recognition camera 9 captures an image of a component E using the flying vision system. The component recognition camera 9 has an angle of view AV that is determined by the characteristics of the attached lens, etc. Furthermore, the component recognition camera 9 has an imaging area CA at a focusing position (within the focal depth) within the angle of view AV. The component recognition camera 9 captures an image of the component E (image capture target) that passes through this imaging area CA.

[0045] That is, in the flying vision method, component E is not temporarily stopped in the imaging area CA and then imaged, but rather, component E is imaged as it passes through the imaging area CA. Fig. 3 shows a state in which component E is sucked and held by nozzle 62 attached to the lower end of shaft 611 of head main body 61. Position P1 in Fig. 3 is the position of nozzle 62 holding component E before it passes through imaging area CA. For example, position P1 is the position immediately after nozzle 62 sucks component E from tape feeder 5.

[0046] Next, the nozzle 62 holding the component E is moved by the second drive mechanism 8 so as to pass through the imaging area CA. Position P2 is a position where the nozzle 62 is midway through the imaging area CA. During this passage, the imaging control unit 23 operates the component recognition camera 9 to capture an image of the component E. Image data acquired by this imaging is sent to the image processing unit 25.

[0047] Thereafter, nozzle 62 passes through imaging area CA and heads to position P3. Position P3 is, for example, a position above board P that corresponds to the mounting position of component E. At position P3, nozzle 62 is lowered, and component E is mounted on board P. According to the flying vision method described above, after component E is picked up, the component E passes through imaging area CA during transportation until mounting, and an image of the component E is captured during the passage, thereby improving the takt time.

[0048] [Comparative Example] As described above, in this embodiment, the exposure time of the component recognition camera 9 is changed according to the passing speed of the component E passing through the imaging area CA. In contrast to this, in the past, the exposure time was set to a constant value regardless of the passing speed. As a comparative example, an example in which the component recognition camera 9 captures an image of the component E with a constant exposure time will be described with reference to FIGS. 4(A) to (C). In the comparative example, the exposure time is set to a fixed value of 10 μs.

[0049] 4(A) shows the imaging result when component E, which is picked up by nozzle 62, passes through imaging area CA at a passing speed V of 0 m / sec, i.e., when imaging is performed while component E is stopped in imaging area CA. The imaging result here shows the amount of blur on the image of component E and the brightness value of the image. When V=0 m / sec, component E does not move from stop position E0, so the amount of blur is naturally 0 μm. Therefore, the brightness value also shows a sharp increase and decrease at the actual edge of component E, resulting in an image with good contrast.

[0050] FIG. 4(B) shows the imaging result when the passing speed of part E is V1=1.0 m / sec. In this case, part E moves from position E0 to position E1 within the exposure time. Specifically, since the exposure time is 10 μs, part E moves by 10 μm during the exposure period. In other words, a blur of 10 μm occurs in the image. That is, an image is acquired in which a blur of 10 μm is added to the actual size of part E in the moving direction. Therefore, the rise and fall of the brightness value is not steep, and the contrast of the image is reduced.

[0051] FIG. 4(C) shows the imaging result when the passing speed V2 of component E is 2.0 m / sec. In this case, during the exposure time, component E moves from position E0 to position E2. Since V1 < V2 at this position E2, it is a position further away from the previous position E1 with respect to position E0. Specifically, since the exposure time is 10 μs, component E moves 20 μm during the exposure period, and a blur amount of 20 μm occurs on the image. That is, an image is obtained in which a blur amount of 20 μm is added to the actual size in the moving direction of component E. Therefore, the rise and fall of the luminance value become even slower, and the contrast of the image further decreases.

[0052] As shown in FIGS. 4(B) and (C), if different blur amounts occur due to differences in the component passing speed, the image quality becomes unstable. That is, since images with different image contrasts are obtained due to differences in the blur amount, it becomes difficult to evaluate the adsorption state of component E based on a uniform standard based on the obtained images. That is, even though the images of component E with passing speeds V1 and V2 are images of the same component E, the image contrasts are different, and the widths of the images are also different. In this case, it becomes difficult to determine whether the nozzle 62 is adsorbing a component E with the correct dimensions, outer shape, and appearance, and whether the component E is adsorbed without tilting in the nozzle axis direction based on the obtained image.

[0053] Furthermore, if the blur amount differs due to differences in the component passing speed, images with different center positions of component E will be obtained. That is, the center position of component E is specified by identifying the edges in the moving direction of the component image, and the midpoint between both edges is specified as the center position of component E. Referring also to FIG. 5, in the case of the image G0 obtained when component E in FIG. 4(A) is in a stopped state, the midpoint between both edges (the rising points of the luminance value) of the luminance value corresponding to the actual size of component E is obtained as the center position C0.

[0054] Similarly, for the component images acquired with the passing speeds V1 and V2 shown in Fig. 4(B) and (C), the center positions C1 and C2 are found based on the brightness values ​​of both edges. Since the amount of blurring differs between the image G1 acquired at the passing speed V1 and the image G2 acquired at the passing speed V2 (V2>V1), the positions of the center positions C1 and C2, which are the midpoints between the two edges, also differ. In other words, the center positions C0, C1, and C2 are mutually shifted. The center position information of the component E is used, for example, as information for evaluating whether the nozzle 62 is picking up the component E without eccentricity. For this reason, if the center positions C1 and C2 differ due to differences in the passing speed of the component E, this may hinder the evaluation of the eccentric pick-up of the component E described above.

[0055] [First embodiment] 6(A) and (B) are diagrams showing a schematic view of a part imaging mode of the first embodiment of the present invention. In this embodiment, the exposure time of the part recognition camera 9 is changed according to the passing speed of the part E through the imaging area CA. FIG. 6(A) shows an imaging mode when the passing speed V1 of the part E (first imaging object) is 1.0 m / sec (first speed). Here, an example is shown in which the exposure control unit 24 sets the exposure time to 10 μs (first exposure time) in imaging when the passing speed is V1. In this case, as in the example of FIG. 4(B), the part E moves 10 μm from position E0 to position E1 within the exposure time. In other words, a blur of 10 μm occurs on the image. In accordance with this blur, the rise and fall of the brightness value becomes slow, and the contrast of the image decreases to a certain degree. However, this contrast decrease is within a range that does not interfere with the part recognition process.

[0056] FIG. 6(B) shows an imaging state when the passing speed V2 of the part E (second imaging object) is 2.0 m / sec (second speed faster than the first speed). Here, an example is shown in which the exposure control unit 24 sets the exposure time to 5 μs (second exposure time) in imaging when the passing speed is V2. That is, the exposure time is set to 1 / 2 of the exposure time when the passing speed is V1, in response to the passing speed V2 being set to twice the passing speed V1. In this case, the part E moves 10 μm from position E0 to position E2 within the exposure time. That is, the amount of blur generated on the image is 10 μm, the same as when the passing speed is V1.

[0057] In this embodiment, when there is a first part E passing through the imaging area CA at a passing speed V1 and a second part E passing through the imaging area CA at a passing speed V2 faster than the first part E, the exposure control unit 24 sets the exposure time for imaging the second part E to be shorter than the exposure time for imaging the first part E. When imaging a moving part E, blurring of the image of the part E is unavoidable in the acquired image. As described in the above comparative example, the amount of image blurring differs depending on the passing speed of the part E passing through the imaging area CA when the exposure time is constant. According to this embodiment, the exposure control unit 24 changes the exposure time of the part recognition camera 9 according to the passing speed of the part E. Therefore, it is possible to suppress the variation in the amount of image blurring between parts E with different passing speeds and to make the contrast of the images of these parts E as uniform as possible.

[0058] Particularly in this embodiment, the exposure control unit 24 sets the exposure time so that the distance traveled by the part E moving at the passing speed V1 or V2 in the imaging area CA within the exposure time is equal. That is, the distance traveled by the part E within the exposure time (10 μs) in the case of the passing speed V1 is 10 μm, and the distance traveled by the part E within the exposure time (5 μs) in the case of the passing speed V2 is also 10 μm. By setting the exposure time in this manner, the amount of blur in the images acquired at the different passing speeds V1 and V2, that is, the image contrast, can be made constant.

[0059] Furthermore, according to this embodiment, the center positions of images of part E that pass at different speeds can also be aligned. With reference to Fig. 7, the image G1 captured at a passing speed V1 and the image G2 captured at a passing speed V2 (V2>V1) have the same amount of blur due to the change in exposure time described above. Therefore, the center positions C1 and C2 obtained for the images G1 and G2 based on both edges of the luminance values ​​are equal. It is also possible to align the center position C0 of the image G0 of the stopped part E with the center positions C1 and C2.

[0060] It is also desirable to associate the amount of blur with the number of pixels of the imaging element of the component recognition camera 9. Fig. 7 shows an example in which images G1 and G2 including the amount of blur coincide with the positions of three pixels, Pixel_1 to 3. That is, the period of illumination and exposure is determined to be three specific pixels in the sub-scanning direction of the imaging element, and the exposure time is determined so that the amount of blur is three pixels regardless of the passing speed of the component E, and the center position is the center pixel of the three specific pixels. By adopting such a determination method, it becomes possible to accurately evaluate the component E on the image.

[0061] As described above, according to this embodiment, the image quality of components E that pass at different speeds can be made constant and the center positions of the images can also be aligned. Therefore, based on the images of components E captured by component recognition camera 9, it becomes possible to accurately determine whether nozzle 62 is picking up a component E with the correct dimensions, outer shape, and appearance, whether component E is being picked up without being tilted in the nozzle axial direction, and whether nozzle 62 is picking up the vicinity of the center position of component E, etc.

[0062] [Examples of imaging processing] Fig. 8 is a time chart showing the imaging process of the first embodiment. Here, a specific example is shown in which the exposure control unit 24 sets the exposure time in accordance with the passing speed of the component E. "CC2" in the top row of the time chart in Fig. 8 is a clock pulse created by the encoder 15 (see Fig. 2) based on a scale pulse generated for each passing unit of the linear scale.

[0063] The encoder 15 detects the amount of movement of the head unit 6 in the X direction, in other words, the amount of movement of the nozzle 62 holding the component E, based on a linear scale attached to the second driving mechanism 8. The clock pulse CC2 is not a direct use of the scale pulse of the encoder 15. The clock pulse CC2 is a pulse obtained by converting the amount of movement of the head unit 6 from the unit of the scale pulse to the unit of the amount of movement (unit distance) of one pixel of the imaging element provided in the component recognition camera 9. For example, it is assumed that the encoder 15 outputs a scale pulse every 1 μm based on the linear scale. And it is assumed that one pixel of the imaging element has a width of 24 μm. In this case, 24 μm is the unit distance. And, every time 24 scale pulses are output, in other words, every time the head unit 6 moves by 24 μm, one pulse of the clock pulse CC2 is output. The shorter the generation interval of such clock pulse CC2, the faster the speed at which the nozzle 62 holding the component E passes through the imaging area CA.

[0064] The "CC2 counter clock" in the second row of the time chart is a counter clock of a predetermined frequency generated by the clock generating unit 181 of the timing generator 18. The frequency of the counter clock is determined according to the required resolution. Here, an example is shown in which a counter clock of 80 MHz is generated.

[0065] The "CC2 cycle counter" is a count value of the "CC2 counter clock" generated during the period Rc during which the clock pulse CC2 outputs one cycle of the pulse. In other words, the "CC2 cycle counter" is the number of "CC2 counter clocks" generated by the clock generating unit 181 during the period required for the head unit 6 to move the unit distance of 24 μm. This counting is performed by the clock counting unit 182. For example, if the head unit 6 moves at 3 m / sec (3 μm / μs), it moves 3 μm per μs, so that it takes 8 μs to move the unit distance of 24 μm. If the "CC2 counter clock" is 80 MHz, 80 clocks are generated per μs. Therefore, the "CC2 counter clock" counted during one cycle of the clock pulse CC2 (a moving period of 24 μm) is 80 clocks x 8 (μs) = 640 clocks.

[0066] 8 is the moving speed of the head unit 6 derived based on the count value of the "CC2 period counter." This moving speed is also the passing speed of the component E through the imaging area CA. "CC1 (external trigger)" is an instruction pulse for the component recognition camera 9 to start imaging. This instruction pulse is generated by the imaging control unit 23 of the control unit 20.

[0067] The "internal trigger" determines the start and end of the exposure period, and includes an exposure start pulse p1 and an exposure stop pulse p2. The exposure start pulse p1 is generated immediately when an instruction pulse of "CC1 (external trigger)" is given. The exposure stop pulse p2 is generated when the "CC2 counter clock" has counted a predetermined number after the exposure start pulse p1 is generated. The period from the exposure start pulse p1 to the exposure stop pulse p2 is the exposure time during which the exposure operation is turned ON by opening the shutter, etc. The illumination operation is also turned ON in accordance with this exposure time. This allows an image of the component E to be acquired.

[0068] In this embodiment, the exposure control unit 24 sets the exposure time based on the moving speed of the head unit 6 immediately before the imaging of the component E. Specifically, the speed acquisition unit 26 acquires the count value of the "CC2 cycle counter" immediately before the generation of the exposure start pulse p1. In FIG. 8, one cycle of the clock pulse CC2 immediately before the generation of the exposure start pulse p1 is shown as a period Rc. The number of clocks of the "CC2 counter clock" counted by the clock counting unit 182 within this period Rc is provided to the speed acquisition unit 26 as information on the passing speed. The provided count value corresponds to the time required for the head unit 6 (component E) to move a unit distance (24 μm) for one pixel immediately before the imaging. As in the above example, if the head unit 6 is moving at 3 m / sec, the speed acquisition unit 26 acquires the count value=640 clocks.

[0069] As shown in FIG. 7, in order to restrict the blur amount of the component image to three pixels, the exposure control unit 24 multiplies the count value of the "CC2 counter clock" acquired by the speed acquisition unit 26 by a coefficient=3 corresponding to three pixels to set the exposure time. In the above example, the exposure control unit 24 sets the time equivalent to 640×3=1920 clocks as the exposure time. Since the above coefficient is a value corresponding to three pixels, it is a coefficient that is set to the same value regardless of the moving speed of the component E. According to such a method of setting the exposure time, the exposure time can be automatically set to a short value when the passing speed of the component E is fast and to a long value when the passing speed of the component E is slow. Furthermore, regardless of the passing speed of the component E passing through the imaging area CA, the image blur amount can be adjusted to a constant value of three pixels.

[0070] [Second embodiment] In the above first embodiment, it is assumed that the head unit 6 moves in the X direction and the part E passes through the imaging area CA along the X direction. In the second embodiment, it is assumed that the part E passes through the imaging area CA in the X direction and the Y direction. In other words, it is assumed that the part E enters the imaging area CA from an oblique direction.

[0071] 9(A) and (B) are diagrams for explaining problems when the part E enters the imaging area CA from an oblique direction. FIG. 9(A) shows an example in which the part E moves along the X direction, assuming the first embodiment. Position P11 in FIG. 9(A) is the position before the nozzle 62 holding the part E enters the imaging area CA. The part E moves along the X direction from this position P11, passes through the imaging area CA, and reaches position P12. The linear scale and encoder 15 attached to the second driving mechanism 8 detect the movement of the head unit 6 in the X direction. Therefore, in the passing mode of the part E in FIG. 9(A), the passing speed of the part E can be accurately grasped based on the output of the encoder 15.

[0072] 9(B) shows an example in which the part E moves at an inclination with respect to the X direction. The part E held by the nozzle 62 moves from position P21 along a direction intermediate between the X and Y directions, passes through the imaging area CA, and reaches position P22. This type of movement is assumed when the nozzle 62 holding the part E passes through the imaging area CA while the head unit 6 is moved in the Y direction by the first driving mechanism 7 (FIG. 1) and also moved in the X direction by the second driving mechanism 8. In this case, the encoder 15 can only detect the amount of movement in the X direction, and therefore cannot accurately grasp the passing speed of the part E.

[0073] 10(A) and (B) are diagrams showing the aspect of component imaging in the second embodiment. As shown in FIG. 9(B), in the case where it is assumed that a component E enters the imaging area CA from an oblique direction and only the amount of movement in the X direction can be detected, it is necessary to provide a means for acquiring the amount of movement in the Y direction.

[0074] 10A illustrates a method for acquiring the approach angle θ of the moving direction F1 of the part E from position P21 to position P22 with respect to the imaging area CA. If the approach angle θ is known, the amount of movement of the part E in the Y direction can be estimated. Therefore, the passing speed of the part E can be determined by multiplying the amount of movement in the X direction detected by the encoder 15 by a coefficient corresponding to the approach angle θ.

[0075] As a specific process, the approach angle acquisition unit 27 (FIG. 2) of the control unit 20 acquires information on the approach angle θ of the component E with respect to the imaging area CA. If the movement path of the nozzle 62 is set in advance, the information on the approach angle θ can be derived from information on the movement path. The speed acquisition unit 26 corrects the passing speed of the component E acquired in the X direction (one axial direction) based on the detection result of the encoder 15 to a passing speed along the approach angle θ. Then, the exposure control unit 24 sets the exposure time based on the corrected passing speed.

[0076] 10B shows an example in which the X-axis speed and Y-axis speed of the movement direction F2 of the part E from position P21 to position P22 are input in advance to the control unit 20. If the X-axis speed and Y-axis speed are known, the speed in the movement direction F2 can be derived.

[0077] In a specific process, the speed acquisition unit 26 acquires information on an X-axis speed (first passing speed) along the X direction (first axis direction) and information on a Y-axis speed (second passing speed) along a Y direction (second axis direction) perpendicular to the X direction in a plane. For example, the information on the X-axis speed can be acquired from the output of the encoder 15, and the information on the Y-axis speed can be acquired from a sensor or the like attached to the first driving mechanism 7. The speed acquisition unit 26 derives a passing speed along the moving direction F2 of the part E based on the acquired X-axis speed and Y-axis speed. Then, the exposure control unit 24 sets an exposure time based on the derived passing speeds.

[0078] According to the second embodiment described above, it is possible to accurately grasp the passing speed of the component E as it enters the imaging area CA from an oblique direction. Therefore, it is possible to cause the exposure control unit 24 to set an appropriate exposure time in accordance with the passing speed.

[0079] [Other embodiments] Although the embodiments of the present invention have been described above, the present invention is not limited to these, and various modified embodiments can be adopted. For example, in the above first embodiment, as shown in FIG. 7, an example was shown in which the exposure time is set so as to completely match the amount of blurring of the component images G1 and G2, which pass at different speeds. The amount of blurring of the component images G1 and G2 does not necessarily have to completely match, and some deviation may occur. Also, in the above embodiment, an example was shown in which the exposure time is determined based on the movement distance of three pixels of the image sensor of the component recognition camera 9. The exposure time may be determined based on other criteria without depending on pixels. [Explanation of symbols]

[0080] 1. Component mounting equipment 6 Head unit (mounting head / moving body) 62 Nozzle (holding part) 7 First Drive Mechanism 8 Second driving mechanism (moving mechanism) 9 Part recognition camera (image capture camera) 15 Encoder (distance measurement part) 181 Clock Generation Unit 182 Clock counter 20 Control section 23 Imaging control section 24 Exposure control section 26 Speed ​​acquisition section 27 Approach angle acquisition part CA Imaging Area E Parts

Claims

1. an imaging camera having a predetermined imaging area and including an imaging element having a plurality of pixels for capturing an image of an imaging target passing through the imaging area; A control unit that controls an imaging operation of the imaging camera, The control unit is a speed acquisition unit that acquires information on a passing speed of an image capture target passing through the image capture area; an exposure control unit that changes an exposure time of the imaging camera in accordance with the passing speed; Including, The exposure control unit predetermines the number of pixels for capturing an image to three specific pixels lined up in the sub-scanning direction, and determines the exposure time so that the image is captured using the three specific pixels regardless of the passing speed, and the center position of the image is the central pixel of the three specific pixels.

2. 2. The object imaging device according to claim 1, When a first image capture object having a first passing speed and a second image capture object having a second passing speed that is faster than the first speed are present, The exposure control unit sets a second exposure time when imaging the second imaging object to be shorter than a first exposure time when imaging the first imaging object.

3. 3. The object imaging device according to claim 2, An imaging device for an object, wherein the exposure control unit sets the first exposure time and the second exposure time so that the distance the first imaging object moves in the imaging area within the first exposure time is equal to the distance the second imaging object moves in the imaging area within the second exposure time.

4. The object imaging device according to any one of claims 1 to 3, The control unit is a clock generating unit that generates a counter clock; A clock counting unit capable of counting the number of occurrences of the counter clock within a specific period of time, the speed acquisition unit acquires a count value of the counter clock within a period required for the image capture object to move a unit distance immediately before the image capture; The exposure control unit sets the exposure time to a time equivalent to a value obtained by multiplying the count value of the counter clock by a coefficient that is set to a constant value corresponding to the three specific pixels.

5. 5. The object imaging device according to claim 4, the imaging target passes through the imaging area by a moving body that moves while holding the imaging target, and a moving distance of the moving body is measured by a distance measuring unit, The clock counting unit counts the number of occurrences of the counter clock within a period during which the distance measuring unit detects the movement of the moving object by a unit distance.

6. The object imaging device according to any one of claims 1 to 5, The control unit further includes an approach angle acquisition unit that acquires information about an approach angle of the image capture object with respect to the image capture area, The velocity acquisition unit corrects the passing velocity of the imaged object acquired in one axial direction to a passing velocity along the approach angle.

7. The object imaging device according to any one of claims 1 to 5, The speed acquisition unit As information on the passing speed of the imaged object, information on a first passing speed in a first axial direction and information on a second passing speed in a second axial direction perpendicular to the first axial direction in a plane of the imaged image are acquired; An imaging device for an object that derives a passing speed along a moving direction of the imaged object based on the first passing speed and the second passing speed.

8. a mounting head having a holding portion for holding a component; a moving mechanism for moving the mounting head; The object imaging device according to any one of claims 1 to 7, the moving mechanism moves the mounting head so that the holder holding the component passes through the imaging area; The control unit causes the imaging camera to perform the imaging operation when the holding unit passes through the imaging area.

Images