Orientation detection device

Abstract

To provide a direction detection device capable of preventing a conveyance of a workpiece to an inadequacy direction.SOLUTION: A direction detection device for detecting a direction of a non-circular workpiece, comprises: a support unit that supports the workpiece; a camera that images the workpiece supported by the support unit and acquires an image containing an outer peripheral edge of the workpiece; a lighting that irradiates the workpiece supported by the support unit; and a control part. The control part contains: a coordinate specification part that specifies a plurality of coordinates indicating a position of the outer peripheral edge contained in the image; an approximation line calculation part that calculates an approximation line that approximates the outer peripheral edge on the basis of the plurality of coordinates; and an outer peripheral edge determination part that determines that the approximation line is not corresponded to the outer peripheral edge of the workpiece in the case where the number of coordinates indicating a position in a predetermined range or a rate from the approximate line is out of a permission range.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an orientation detection device for detecting the orientation of a workpiece.

Background Art

[0002] In the manufacturing process of device chips, a wafer in which devices are formed in a plurality of regions partitioned by a plurality of streets (division planned lines) arranged in a grid pattern is used. By dividing this wafer along the streets, a plurality of device chips each having a device can be obtained. The device chips are incorporated into various electronic devices such as mobile phones and personal computers.

[0003] For wafer dicing, a cutting device that cuts a workpiece with an annular cutting blade, a laser processing device that processes a workpiece by irradiating a laser beam, etc. are used. In recent years, with the miniaturization of electronic devices, device chips are required to be thinned. Therefore, a process of thinning the wafer may be performed before wafer dicing. For wafer thinning, a grinding device that grinds a workpiece with a grinding wheel including a grinding stone, a polishing device that polishes a workpiece with a disk-shaped polishing pad, etc. are used.

[0004] Each of the above various processing devices is equipped with a chuck table for holding a workpiece, and the workpiece is held on the holding surface of the chuck table during processing of the workpiece. Note that the holding surface of the chuck table is designed according to the shape of the workpiece so that the workpiece is properly held by the chuck table. Therefore, when the workpiece is non-circular, it is necessary to align the orientation of the workpiece and the orientation of the holding surface when transporting and placing the workpiece on the chuck table.

[0005] For example, Patent Document 1 discloses a grinding device for grinding a disk-shaped wafer having a linear notch (orientation flat) indicating the crystal orientation formed on the outer peripheral portion. A notch corresponding to the orientation flat of the wafer is formed on the holding surface (adsorbing surface) of the chuck table mounted on this grinding device. When transporting the wafer onto the chuck table, first, the wafer is imaged by a camera (imaging unit), and the position of the orientation flat is specified based on the image of the wafer. Then, the orientation of the wafer is adjusted so that the position of the orientation flat coincides with the position of the notch on the holding surface.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] As described above, when processing a non-circular workpiece with a processing device, it is necessary to place the workpiece on the chuck table in a predetermined orientation. Therefore, before transporting the workpiece to the chuck table, a process for specifying the orientation of the workpiece is performed.

[0008] For example, when processing a rectangular workpiece with a processing device, first, the workpiece is imaged by a camera to obtain an image including an image of the outer peripheral edge (outline) of the workpiece. Next, a plurality of coordinates indicating the position of the outer peripheral edge of the workpiece are specified by image processing, and an approximate line approximating the outer peripheral edge of the workpiece is calculated based on the specified coordinates. Then, regarding the calculated approximate line as the outer peripheral edge of the workpiece, the angle of the outer peripheral edge of the workpiece with respect to the holding surface of the chuck table is adjusted.

[0009] However, depending on the imaging conditions of the workpiece, an approximation line that accurately approximates the outer peripheral edge of the workpiece may not be calculated. For example, when foreign matter (dust) adheres to the outer peripheral edge of the workpiece, or when the illumination illuminating the workpiece is partially deteriorated, etc., the coordinates of the outer peripheral edge of the workpiece are not correctly specified, and an approximation line with a large error from the actual outer peripheral edge of the workpiece may be calculated. As a result, the workpiece may not be conveyed to the chuck table in a direction suitable for the shape of the holding surface, and a situation may occur where the workpiece is not properly held by the chuck table.

[0010] The present invention has been made in view of such problems, and an object thereof is to provide an orientation detection device capable of preventing the workpiece from being conveyed in an inappropriate orientation.

Means for Solving the Problems

[0011] According to one aspect of the present invention, there is provided an orientation detection device for detecting the orientation of a non-circular workpiece, including a support unit that supports the workpiece, a camera that images the workpiece supported by the support unit to obtain an image including the outer peripheral edge of the workpiece, an illumination that illuminates the workpiece supported by the support unit, A display unit, and a control unit. The control unit includes calculate the brightness of a plurality of pixels included in the image along a direction intersecting the outer peripheral edge included in the image, and identify the coordinates of a plurality of pixels whose brightness difference from adjacent pixels is equal to or greater than a threshold value as a plurality of coordinates indicating the position of the outer peripheral edge a coordinate specifying unit, an approximation line calculating unit that calculates an approximation line that approximates the outer peripheral edge based on a plurality of the coordinates, and an outer peripheral edge determination unit that determines that the approximation line does not correspond to the outer peripheral edge of the workpiece when the number or ratio of the coordinates indicating positions within a predetermined range from the approximation line is outside the allowable range. a display control unit that causes the display unit to display, together with the image, an identification mark indicating the position of a row or column including the coordinates indicating a position outside a predetermined range from the approximate line, or an identification mark indicating the position of a row or column not including a pixel whose brightness difference from an adjacent pixel is equal to or greater than a threshold value; An orientation detection device including the above is provided.

[0012] Preferably, the approximation line calculating unit calculates a straight line that approximates the outer peripheral edge as the approximation line. 。

[0013] Also preferably, the display control unit causes the display unit to display the identification mark so as not to overlap the plurality of coordinates. Also preferably, the display control unit causes the display unit to display, together with the image, a mark indicating that the coordinates indicating a position outside a predetermined range from the approximate line have been detected, or a mark indicating that no pixel whose brightness difference from an adjacent pixel is equal to or greater than a threshold value has been detected. Also, preferably, the identification mark is constituted by a color, a number, a character, a figure, a pattern, or a combination thereof.

Effects of the Invention

[0014] The orientation detection device according to one aspect of the present invention determines whether an approximate line approximating the outer peripheral edge of a workpiece corresponds to the outer peripheral edge of the workpiece based on the distances between a plurality of coordinates indicating the positions of the outer peripheral edge of the workpiece and the approximate line. Thereby, it is possible to prevent the orientation of the workpiece from being specified in a state where the outer peripheral edge of the workpiece is approximated by an inappropriate approximate line and the workpiece from being conveyed in an inappropriate orientation.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0016] Hereinafter, embodiments according to one aspect of the present invention will be described with reference to the accompanying drawings. First, a configuration example of the orientation detection device (orientation detection mechanism) according to the present embodiment will be described. FIG. 1 is a perspective view showing an orientation detection device (orientation detection mechanism) 2.

[0017] For example, the orientation detection device 2 is connected to or mounted on various processing devices, and detects the orientation of a workpiece being processed by the processing device. That is, the orientation detection device 2 can form a part of the processing device. In FIG. 1, the X-axis direction (the first horizontal direction, the left-right direction) and the Y-axis direction (the second horizontal direction, the front-back direction) are perpendicular to each other. Also, the Z-axis direction (the vertical direction, the up-down direction, the height direction) is perpendicular to the X-axis direction and the Y-axis direction.

[0018] The orientation detection device 2 includes a rectangular parallelepiped base 4 that supports or houses each component constituting the orientation detection device 2. In front of the base 4, a pair of cassette bases 6A and 6B are provided. On the upper surfaces of the cassette bases 6A and 6B, cassettes 8 capable of accommodating a plurality of workpieces 11 can be mounted.

[0019] The workpiece 11 is a non-circular plate-like object corresponding to an object to be processed by a processing device to which the orientation detection device 2 is connected or mounted. For example, the workpiece 11 is formed in a rectangular shape in a plan view, and includes surfaces (first surfaces) 11a and back surfaces (second surfaces) 11b that are substantially parallel to each other, and an outer peripheral edge (side surface) 11c connected to the surfaces 11a and the back surfaces 11b.

[0020] Examples of the workpiece 11 include package substrates such as CSP (Chip Size Package) substrates and QFN (Quad Flat Non-leaded package) substrates formed in a rectangular shape. For example, a package substrate is formed by mounting a plurality of device chips on a rectangular base substrate and covering the plurality of device chips with a sealing material (mold resin) made of resin. By dividing the package substrate by cutting, laser processing, etc., a package device including a plurality of packaged device chips is manufactured. Also, by subjecting the package substrate before division to grinding, polishing, etc. to thin the package substrate, a thinned package device can be obtained.

[0021] However, there is no limitation as long as the shape of the workpiece 11 is non-circular. Also, there are no limitations on the type, material, structure, size, etc. of the workpiece 11. Other examples of the workpiece 11 include wafers (substrates) made of semiconductor (Si, GaAs, InP, GaN, SiC, etc.), sapphire, glass, ceramics, resin, metal, etc. For example, the workpiece 11 may be a disk-shaped silicon wafer. An orientation flat indicating the crystal orientation of the silicon wafer may be formed on the outer peripheral portion of the silicon wafer. In this case, the silicon wafer becomes non-circular.

[0022] For example, a silicon wafer is partitioned into a plurality of rectangular regions by a plurality of streets (lines to be divided) arranged in a grid pattern so as to intersect each other. Also, devices such as IC (Integrated Circuit), LSI (Large Scale Integration), LED (Light Emitting Diode), and MEMS (Micro Electro Mechanical Systems) devices are formed in each of the plurality of regions partitioned by the streets. By dividing this silicon wafer along the streets, a plurality of device chips each having a device are manufactured. Also, by thinning the silicon wafer before dividing the silicon wafer, a thinned device chip can be obtained.

[0023] For example, the cassette 8 is formed in a rectangular parallelepiped shape and is arranged on the cassette stand 6A or the cassette stand 6B so that the depth direction is along the Y-axis direction. Also, a plurality of storage shelves capable of accommodating the workpiece 11 are provided in multiple stages inside the cassette 8. Specifically, a pair of guide rails along the depth direction of the cassette 8 are provided in multiple stages along the height direction of the cassette 8 on a pair of inner walls facing each other inside the cassette 8. Then, the workpiece 11 is accommodated in the storage shelf so that the longitudinal direction is along the depth direction of the cassette 8 and is supported by the pair of guide rails. Therefore, the orientations of the plurality of workpieces 11 accommodated in the cassette 8 are generally the same.

[0024] At the front end of the base 4, a rectangular opening 4a that opens on the upper surface of the base 4 is provided. Inside the opening 4a, a conveying mechanism (conveying unit) 10 for conveying the workpiece 11 is provided. The conveying mechanism 10 includes a plate-shaped holding portion 12 that holds the workpiece 11, and an articulated arm 14 that can position the holding portion 12 at an arbitrary position.

[0025] For example, the holding portion 12 is formed in a rectangular shape, and the width and thickness of the holding portion 12 are set so that the holding portion 12 can be inserted into the storage shelf of the cassette 8. Further, at both ends in the longitudinal direction of the holding portion 12, a plurality of suction holes 12b that open on the upper surface 12a side of the holding portion 12 are provided. Each of the suction holes 12b is connected to a suction source (not shown) such as an ejector via a flow path (not shown), a valve (not shown), etc. formed inside the holding portion 12.

[0026] When the holding portion 12 is moved by the articulated arm 14 and inserted into the cassette 8, the upper surface 12a of the holding portion 12 faces the lower surface (back surface 11b) of the workpiece 11 inside the cassette 8. Then, when the suction force (negative pressure) of the suction source is applied to the suction holes 12b, the lower surface side of the workpiece 11 is suction-held by the holding portion 12. When the holding portion 12 is pulled out from the cassette 8 by the articulated arm 14 in this state, the workpiece 11 is carried out of the cassette 8.

[0027] Note that the suction holes 12b may be provided on the lower surface side of the holding portion 12. In this case, the upper surface (front surface 11a) side of the workpiece 11 is held by the holding portion 12. Further, the holding portion 12 may be a Bernoulli type non-contact suction pad. In this case, the holding portion 12 holds the workpiece 11 in a non-contact manner using the Bernoulli effect.

[0028] Behind the opening 4a and the conveying mechanism 10, a detection unit 16 for detecting the orientation of the workpiece 11 is provided. The detection unit 16 includes a support unit 18 that supports the workpiece 11, and a camera (imaging unit) 20 that images the workpiece 11 supported by the support unit 18. Note that the support unit 18 is provided inside a rectangular opening 4b that opens on the upper surface of the base 4.

[0029] The workpiece 11 accommodated in the cassette 8 is conveyed onto the support unit 18 of the detection unit 16 by the conveying mechanism 10. Then, the orientation of the workpiece 11 is detected by the detection unit 16. Details of the configuration and function of the detection unit 16 will be described later (see FIGS. 2(A) and 2(B)).

[0030] In addition, the orientation detection device 2 includes a display unit (display unit, display device) 22 that displays various types of information. The display unit 22 is composed of various displays. For example, a touch panel display is used as the display unit 22. In this case, the operator can input information to the orientation detection device 2 by touching the display unit 22. That is, the display unit 22 also functions as an input unit (input unit, input device) for inputting various types of information to the orientation detection device 2. However, the input unit may be a mouse, keyboard, operation panel, etc. provided separately and independently from the display unit 22.

[0031] Each component (conveying mechanism 10, detection unit 16, display unit 22, etc.) constituting the orientation detection device 2 is connected to a control unit (control unit, control device) 24. The control unit 24 operates the orientation detection device 2 by generating and outputting a control signal for controlling the operation of each component of the orientation detection device 2.

[0032] For example, the control unit 24 is constituted by a computer and includes an arithmetic unit that performs arithmetic operations necessary for the operation of the orientation detection device 2, and a storage unit that stores various types of information (data, programs, etc.) necessary for the operation of the orientation detection device 2. The arithmetic unit is constituted by including a processor such as a CPU (Central Processing Unit). In addition, the storage unit is constituted by including memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory) that function as a main storage device, an auxiliary storage device, etc.

[0033] The orientation detection device 2 is connected to or mounted on various processing devices that process the workpiece 11. For example, the processing device includes a chuck table that holds the workpiece 11, a processing unit that processes the workpiece 11, and a transport mechanism that transports the workpiece 11. FIG. 1 shows the chuck table (holding table) 26 and the transport mechanism (transport unit) 28 provided in the processing device. Examples of the processing device include a cutting device that cuts the workpiece, a grinding device that grinds the workpiece, a polishing device that polishes the workpiece, a laser irradiation device that processes the workpiece by irradiating a laser beam, and the like.

[0034] The cutting device includes a processing unit (cutting unit) that cuts the workpiece 11. The cutting unit includes a spindle, and an annular cutting blade is mounted on the tip of the spindle. By cutting into the workpiece 11 held by the chuck table 26 while rotating the cutting blade, the workpiece 11 is cut.

[0035] The grinding device includes a processing unit (grinding unit) that grinds the workpiece 11. The grinding unit includes a spindle, and an annular grinding wheel having a grinding stone is mounted on the tip of the spindle. By bringing the grinding stone into contact with the workpiece 11 held by the chuck table 26 while rotating the grinding stone, the workpiece 11 is ground.

[0036] The polishing device includes a processing unit (polishing unit) that polishes the workpiece 11. The polishing unit includes a spindle, and a disk-shaped polishing pad is mounted on the tip of the spindle. By bringing the polishing pad into contact with the workpiece 11 held by the chuck table 26 while rotating the polishing pad, the workpiece 11 is polished.

[0037] The laser processing apparatus includes a processing unit (laser irradiation unit) that irradiates a laser beam for processing the workpiece 11. For example, the laser irradiation unit includes a laser oscillator that pulse-oscillates a laser of a predetermined wavelength, and a condenser that condenses the laser beam emitted from the laser oscillator. By irradiating the workpiece 11 held by the chuck table 26 with the laser beam from the laser irradiation unit, laser processing is performed on the workpiece 11.

[0038] The chuck table 26 and the processing unit included in the processing apparatus are arranged, for example, behind the detection unit 16. The upper surface of the chuck table 26 is a flat surface substantially parallel to the horizontal direction (XY plane direction), and constitutes a holding surface 26a for holding the workpiece 11. The holding surface 26a is connected to a suction source such as an ejector via a flow path, a valve, etc. formed inside the chuck table 26. When the suction force (negative pressure) of the suction source is applied to the holding surface 26a with the workpiece 11 placed on the chuck table 26, the workpiece 11 is sucked and held by the chuck table 26.

[0039] The workpiece 11 whose orientation is detected by the detection unit 16 is conveyed to the chuck table 26 by the conveying mechanism 28. Thereafter, the workpiece 11 is processed by the processing unit while being held by the chuck table 26.

[0040] Here, the holding surface 26a of the chuck table 26 is designed according to the shape of the workpiece 11 so that the workpiece 11 is properly held by the chuck table 26. For example, when the workpiece 11 is rectangular, a rectangular holding area for holding the workpiece 11 is provided on the chuck table 26. Therefore, when the workpiece 11 is non-circular, it is necessary to align the orientation of the workpiece 11 and the orientation of the holding surface 26a when conveying and placing the workpiece 11 on the chuck table 26.

[0041] Therefore, before the workpiece 11 is conveyed to the chuck table 26, the orientation of the workpiece 11 is detected by the detection unit 16. Then, the workpiece 11 is conveyed by the conveying mechanism 28 so as to be placed on the chuck table 26 in a predetermined orientation. For example, the conveying mechanism 28 is configured to be rotatable about a rotation axis substantially parallel to the Z-axis direction while holding the workpiece 11. In this case, by rotating the conveying mechanism 28 holding the workpiece 11, the workpiece 11 can be placed on the chuck table 26 in a desired orientation.

[0042] Next, the details of the detection unit 16 will be described. FIG. 2(A) is a partial cross-sectional front view showing the detection unit 16, and FIG. 2(B) is a partial cross-sectional side view showing the detection unit 16.

[0043] The detection unit 16 includes a support unit 18 that supports the workpiece 11 by a pair of support bases 30. The pair of support bases 30 are formed, for example, in a rectangular parallelepiped shape and are arranged at a distance from each other in the X-axis direction. The upper surface of the support base 30 is a flat surface substantially parallel to the horizontal direction (XY plane direction) and constitutes a support surface 30a for supporting the workpiece 11.

[0044] The height positions (positions in the Z-axis direction) of the pair of support surfaces 30a are substantially the same, and the distance d between the pair of support surfaces 30a is smaller than the width of the workpiece 11. When the workpiece 11 is conveyed to the detection unit 16, both end portions in the width direction of the workpiece 11 are supported by the pair of support bases 30, and the workpiece 11 is arranged substantially horizontally. For example, the workpiece 11 is arranged on the pair of support bases 30 such that the surface 11a side is exposed upward and the back surface 11b side is supported by the support surface 30a.

[0045] Below the support base 30, an illumination 32 for illuminating the workpiece 11 supported by the support unit 18 is provided. For example, the illumination 32 includes a plurality of light sources 34 and a cover (case) 36 that covers the plurality of light sources 34.

[0046] As the light source 34, for example, an LED can be used. Note that there is no limitation on the wavelength (color) of the light emitted by the LED as long as the light can be received by the camera 20. Further, the cover 36 is formed, for example, in a rectangular parallelepiped shape having substantially the same width and depth as the support base 30. And a plurality of light sources 34 are arranged at predetermined intervals along the width direction (X-axis direction) and the depth direction (Y-axis direction) of the cover 36 and are covered by the cover 36. Also, a plate-shaped diffusion plate 38 is provided between the support base 30 and the illumination 32. The diffusion plate 38 diffuses the light emitted by the light source 34 toward the support base 30 side.

[0047] The support base 30, the cover 36, and the diffusion plate 38 are made of a transparent body having transparency with respect to the light emitted by the light source 34. And the light emitted by the light source 34 passes through the cover 36, the diffusion plate 38, and the support base 30 and irradiates the workpiece 11. As a result, the entire workpiece 11 is illuminated by the illumination 32.

[0048] Above the support unit 18, the camera 20 is arranged so as to overlap the region between the pair of support surfaces 30a. And the workpiece 11 held by the support unit 18 is imaged by the camera 20. The camera 20 includes an imaging element such as a CCD (Charged-Coupled Devices) sensor or a CMOS (Complementary Metal-Oxide-Semiconductor) sensor and generates an image of the workpiece 11.

[0049] By illuminating the workpiece 11 with the illumination 32 and imaging the workpiece 11 with the camera 20, an image of the workpiece 11 is acquired. Note that the imaging region (field of view) 20a of the camera 20 is set so as to cover the entire pair of support surfaces 30a. Therefore, when the workpiece 11 is imaged by the camera 20, an image including the entire workpiece 11 is acquired.

[0050] FIG. 3 is an image diagram showing an image (captured image) 40 of the workpiece 11 acquired by the camera 20. When the workpiece 11 is imaged by the camera 20, an image 40 representing the entire surface 11a side of the workpiece 11 is acquired. Therefore, the image 40 includes an outer peripheral edge region 42 corresponding to a region representing at least a part of the outer peripheral edge 11c of the workpiece 11.

[0051] As described above, the support base 30, the cover 36, and the diffusion plate 38 (see FIGS. 2(A) and 2(B)) are transparent, and the entire workpiece 11 supported by the pair of support surfaces 30a is illuminated by the illumination 32. Therefore, an image of the outer peripheral edge 11c corresponding to the contour (four sides) of the workpiece 11 clearly appears in the image 40.

[0052] Since a plurality of workpieces 11 are accommodated in the cassette 8 (see FIG. 1) along the same direction, by transporting the workpiece 11 from the cassette 8 to the support unit 18 by the transport mechanism 10 (see FIG. 1) with a constant operation, the workpiece 11 is disposed on the pair of support units 18 in a generally constant orientation. However, due to variations in the orientation of the workpiece 11 in the cassette 8 and errors in the operation of the transport mechanism 10, etc., the orientation of the workpiece 11 disposed on the pair of support bases 30 may be slightly deviated. For example, the workpiece 11 may be disposed on the support unit 18 in a state where its longitudinal direction is slightly inclined with respect to the Y-axis direction. In this case, as shown in FIG. 3, the image 40 shows the slightly inclined workpiece 11.

[0053] The image 40 acquired by the camera 20 is input to the control unit 24 (see FIG. 1). Then, the control unit 24 detects the orientation of the workpiece 11 by performing image processing on the image 40.

[0054] FIG. 4 is a block diagram showing the control unit 24. In addition to the blocks showing the functional configuration of the control unit 24, FIG. 4 schematically shows the camera 20 and the display unit 22. Hereinafter, the configuration and operation of the control unit 24 shown in FIG. 4 will be described with reference to FIGS. 5 to 7.

[0055] The control unit 24 includes a processing unit 50 and a storage unit 60. The processing unit 50 processes information (signals, data, etc.) input from the outside, and generates and outputs various types of information (signals, data, etc.) to the outside. Further, the storage unit 60 stores various types of information (data, programs, etc.) used in the processing by the processing unit 50.

[0056] Specifically, the processing unit 50 includes a coordinate specifying unit 52 that specifies a plurality of coordinates indicating the position of the outer peripheral edge 11c of the workpiece 11 included in the image 40 (see FIG. 3) acquired by the camera 20. Further, the storage unit 60 includes a coordinate storage unit 62 that stores the coordinates specified by the coordinate specifying unit 52. For example, the coordinate specifying unit 52 specifies the coordinates of the outer peripheral edge 11c of the workpiece 11 based on the brightness of the pixels included in the image 40, and stores them in the coordinate storage unit 62.

[0057] FIG. 5 is an image diagram showing the outer peripheral edge region 42 of the image 40. The image 40 is composed of a plurality of pixels 70 arranged along the X-axis direction and the Y-axis direction, and the workpiece 11 is represented in the image 40 according to the brightness of each pixel 70.

[0058] The outer peripheral edge region 42 of the image 40 includes a dark region 72A where the brightness of the pixels 70 is low and a bright region 72B where the brightness of the pixels 70 is high. The dark region 72A corresponds to the region where the workpiece 11 exists, and the bright region 72B corresponds to the region where the workpiece 11 does not exist. Also, the boundary between the dark region 72A and the bright region 72B corresponds to the outer peripheral edge 11c of the workpiece 11.

[0059] First, the coordinate specifying unit 52 calculates the brightness of a plurality of pixels 70 along the direction intersecting with the outer peripheral edge 11c (see FIG. 3) of the workpiece 11 included in the outer peripheral edge region 42 of the image 40. For example, as shown in FIG. 5, the coordinate specifying unit 52 sequentially calculates the brightness of a plurality of pixels 70 belonging to one row parallel to the X-axis direction.

[0060] Next, the coordinate specifying unit 52 calculates the difference in brightness between two adjacent pixels 70, and compares the calculated brightness difference with a threshold value stored in the storage unit 60 in advance. Then, the coordinate specifying unit 52 specifies the coordinates of the pixel 70 whose brightness difference from the adjacent pixel 70 is equal to or greater than the threshold value as the coordinates 74 indicating the position of the outer peripheral edge 11c of the workpiece 11. Specifically, at the boundary between the dark region 72A and the bright region 72B, a pixel 70 with low brightness and a pixel 70 with high brightness are adjacent, and the brightness difference between the two is equal to or greater than the threshold value. Then, the coordinate specifying unit 52 selects the coordinates of one of the pixel 70 with low brightness and the pixel 70 with high brightness that are adjacent to each other (the pixel 70 with high brightness in FIG. 5) as the coordinates 74.

[0061] Next, the coordinate specifying unit 52 sequentially calculates the brightness of a plurality of pixels 70 belonging to other rows parallel to the X-axis direction, and specifies the coordinates 74 in the same procedure. Although FIG. 5 shows an example in which the brightness of the pixel 70 is calculated every three rows, the number of rows and the interval at which the brightness of the pixel 70 is calculated can be freely set. For example, in the outer peripheral edge region 42, the brightness of 100 rows of pixels 70 is calculated, and 100 coordinates 74 are specified.

[0062] Depending on the imaging conditions of the workpiece 11, the coordinates 74 indicating the position of the outer peripheral edge 11c of the workpiece 11 may not be correctly acquired. For example, when foreign matter (dust) adheres to the outer peripheral edge 11c of the workpiece 11, or when the illumination 32 (see FIGS. 2(A) and 2(B)) illuminating the workpiece 11 is partially deteriorated, an irregular portion (dark region 72C) protruding toward the bright region 72B side in the dark region 72A, or a portion where the brightness of the pixel 70 is unclear (intermediate region 72D) may appear in the image 40. Then, in the row including the dark region 72C, an irregular coordinate 74 (coordinate 74A) separated from other coordinates 74 may be detected. Also, in the row including the intermediate region 72D, it may not be possible to detect a pixel 70 whose brightness difference from an adjacent pixel 70 is equal to or greater than the threshold value.

[0063] In addition, in the above description, the case where the coordinate specifying unit 52 specifies the coordinate 74 indicating the position of the outer peripheral edge 11c corresponding to the long side (the right side in FIG. 3) of the workpiece 11 has been described. However, the coordinate specifying unit 52 may specify the coordinate 74 indicating the position of the outer peripheral edge 11c corresponding to the short side (the upper side or the lower side in FIG. 3) of the workpiece 11. In this case, the coordinate specifying unit 52 sequentially calculates the brightness of a plurality of pixels 70 belonging to a column parallel to the Y-axis direction.

[0064] Next, the coordinate specifying unit 52 (see FIG. 4) accesses the storage unit 60 and stores the plurality of specified coordinates 74 in the coordinate storage unit 62. If there is a row or column in which a pixel 70 having a brightness difference with an adjacent pixel 70 equal to or greater than the threshold value cannot be detected, the coordinate specifying unit 52 may store the coordinates of that row or column in the coordinate storage unit 62.

[0065] In addition, the processing unit 50 includes an approximate line calculation unit 54 that calculates an approximate line approximating the outer peripheral edge 11c of the workpiece 11 based on the plurality of coordinates 74 specified by the coordinate specifying unit 52. Further, the storage unit 60 includes an approximate line storage unit 64 that stores the approximate line calculated by the approximate line calculation unit 54.

[0066] FIG. 6 is an image diagram showing the outer peripheral edge region 42 of the image 40 and the approximate line 76. For example, when the workpiece 11 is rectangular and the outer peripheral edge 11c is linear (see FIG. 1 etc.), the approximate line calculation unit 54 reads out the plurality of coordinates 74 stored in the coordinate storage unit 62 and fits the plurality of coordinates 74 with a linear function using the least squares method. Thereby, an approximate line 76 that is a straight line corresponding to the outer peripheral edge 11c of the workpiece 11 is calculated. Then, the approximate line calculation unit 54 (see FIG. 4) accesses the storage unit 60 and stores the calculated approximate line 76 in the approximate line storage unit 64.

[0067] Note that the calculation method of the approximate line 76 can be appropriately selected according to the shape of the outer peripheral edge 11c of the workpiece 11. For example, when the outer peripheral edge 11c of the workpiece 11 is non-linear, the plurality of coordinates 74 may be fitted with a function of the second order or higher.

[0068] Further, the processing unit 50 includes an outer peripheral edge determination unit 56 that determines whether or not the approximate line 76 calculated by the approximate line calculation unit 54 corresponds to the outer peripheral edge 11c of the workpiece 11. For example, the outer peripheral edge determination unit 56 determines whether or not the approximate line 76 corresponds to the outer peripheral edge 11c of the workpiece 11 based on the distance between the coordinates 74 and the approximate line 76.

[0069] Specifically, the outer peripheral edge determination unit 56 is input with a plurality of coordinates 74 stored in the coordinate storage unit 62 and the approximate line 76 stored in the approximate line storage unit 64. Then, the outer peripheral edge determination unit 56 calculates the distance between each of the plurality of coordinates 74 and the approximate line 76.

[0070] Next, the outer peripheral edge determination unit 56 calculates the number or ratio of the coordinates 74 indicating positions within a predetermined range from the approximate line 76, and determines whether or not the number or ratio of the coordinates 74 is within the allowable range. For example, the storage unit 60 stores in advance a threshold value of the distance from the approximate line 76. Then, the outer peripheral edge determination unit 56 compares the distance from the approximate line 76 to the coordinates 74 with the threshold value to determine whether or not each of the plurality of coordinates 74 indicates a position inside a predetermined distance (within the allowable area) from the approximate line 76. Then, the number of the coordinates 74 (coordinates within the area) indicating positions within the allowable area and the number of the coordinates 74 (coordinates outside the area) indicating positions outside the allowable area are counted respectively.

[0071] Furthermore, the storage unit 60 stores in advance a threshold value that defines the allowable range (lower limit value) of the number or ratio of the coordinates within the area. Then, the outer peripheral edge determination unit 56 compares the number or ratio of the coordinates within the area with the threshold value to determine whether or not the number or ratio of the coordinates within the area is within the allowable range (equal to or greater than the lower limit value).

[0072] When a plurality of coordinates 74 are appropriately identified as coordinates indicating the outer peripheral edge 11c of the workpiece 11, the number of coordinates 74 indicating on or in the vicinity of the approximate line 76 increases, and the number or ratio of the in-area coordinates is within the allowable range (equal to or higher than the lower limit value). In this case, the outer peripheral edge determination unit 56 determines that the approximate line 76 corresponds to the outer peripheral edge 11c of the workpiece 11. On the other hand, when a plurality of coordinates 74 are not appropriately identified as coordinates indicating the outer peripheral edge 11c of the workpiece 11, the number of coordinates 74 indicating on or in the vicinity of the approximate line 76 decreases, and the number or ratio of the in-area coordinates is outside the allowable range (less than the lower limit value). In this case, the outer peripheral edge determination unit 56 determines that the approximate line 76 does not correspond to the outer peripheral edge 11c of the workpiece 11.

[0073] Further, the processing unit 50 includes an operation control unit 58 that controls the operation of the orientation detection device 2. The operation control unit 58 outputs a control signal to each component of the orientation detection device 2 according to the result of the determination by the outer peripheral edge determination unit 56, and controls the operation of each component. For example, the operation control unit 58 includes a display control unit 58a that controls the display unit 22. The display control unit 58a controls the information displayed on the display unit 22 by outputting a control signal to the display unit 22.

[0074] When the outer peripheral edge determination unit 56 determines that the approximate line 76 corresponds to the outer peripheral edge 11c of the workpiece 11, the orientation of the workpiece 11 is determined based on the approximate line 76. That is, the approximate line 76 is regarded as the same as the outer peripheral edge 11c of the workpiece 11, and the orientation of the workpiece 11 is specified based on the inclination of the approximate line 76. Then, the workpiece 11 is transported from the support unit 18 to the chuck table 26 by the transport mechanism 28 (see FIG. 1). At this time, the orientation of the workpiece 11 is adjusted by the rotation of the transport mechanism 28.

[0075] On the other hand, when the approximation line 76 is determined by the outer peripheral edge determination unit 56 not to correspond to the outer peripheral edge 11c of the workpiece 11, the orientation detection device 2 notifies the operator of an error. For example, the display control unit 58a outputs a control signal to the display unit 22 to cause the display unit 22 to display a message, an image, etc., informing that the orientation of the workpiece 11 has not been appropriately detected. Further, the orientation detection device 2 may include an indicator lamp that notifies the operator of an error by lighting or blinking, or a speaker that notifies the operator of an error by sound or voice.

[0076] FIG. 7 is an image diagram showing the outer peripheral edge region 42 of the image 40, the approximation line 76, and the identification marks 78, 80A, 80B. When it is determined that the approximation line 76 does not correspond to the outer peripheral edge 11c of the workpiece 11, the display control unit 58a may cause the display unit 22 to display the outer peripheral edge region 42 of the image 40 and the identification marks 78, 80A, 80B indicating the positions where the coordinates 74 have not been appropriately specified.

[0077] The identification mark 78 is a mark indicating a position where there is an abnormality in specifying the coordinates 74. Specifically, the identification mark 78 indicates the position of a row or column including the coordinates 74 (off-area coordinates) outside a predetermined range from the approximation line 76, or the position of a row or column where no pixel 70 having a brightness difference with an adjacent pixel 70 equal to or greater than a threshold value is detected. For example, an "x" mark is displayed as the identification mark 78 at a position overlapping the target row on the image 40. By displaying the identification mark 78 together with the image 40 on the display unit 22, the operator can instantaneously grasp the position where there is an abnormality in detecting the outer peripheral edge 11c of the workpiece 11.

[0078] On the other hand, the identification marks 80A, 80B are marks indicating the content of the abnormality. Specifically, the identification mark 80A indicates that coordinates 74 (off-area coordinates) outside a predetermined range from the approximation line 76 have been detected. Further, the identification mark 80B indicates that no pixel 70 having a brightness difference with an adjacent pixel 70 equal to or greater than a threshold value has been detected.

[0079] For example, as the identification mark 80A, a symbol “>” indicating that there is a row or column including outer area coordinates is displayed adjacent to the identification mark 78 at a position overlapping with that row or column. Also, for example, as the identification mark 80B, a symbol “?” indicating that there is a row or column in which no pixel 70 having a brightness difference with an adjacent pixel 70 equal to or greater than a threshold value is detected is displayed adjacent to the identification mark 78 at a position overlapping with that row or column. In this way, by displaying the identification marks 80A and 80B that simply indicate the content of the abnormality together with the image 40 on the display unit 22, the operator can instantaneously grasp the content of the detection abnormality of the outer peripheral edge 11c.

[0080] Note that there is no limitation on the form of the identification marks 78, 80A, and 80B displayed on the display unit 22, and the identification marks 78, 80A, and 80B can be freely configured by colors, numbers, characters, figures, patterns, or combinations thereof. For example, the identification mark 78 may be a figure such as an arrow, or may be displayed by representing the pixels 70 belonging to the row or column to be displayed in a different color or pattern from the pixels 70 belonging to other rows or columns. Also, the identification marks 80A and 80B may be a message indicating the content of the abnormality, an error number corresponding to the content of the abnormality, or the like.

[0081] Next, a specific example of a method for detecting the orientation of the workpiece 11 using the orientation detection device 2 will be described. FIG. 8 is a flowchart showing the method for detecting the orientation of the workpiece 11.

[0082] When detecting the orientation of the workpiece 11, first, a cassette 8 (see FIG. 1) containing a plurality of workpieces 11 is placed on the cassette table 6A or the cassette table 6B. Then, the workpiece 11 accommodated in the cassette 8 is transported to the support unit 18 by the transport mechanism 10. Thereafter, while illuminating the workpiece 11 supported by the pair of support bases 30 with illumination 32 (see FIGS. 2(A) and 2(B)), the workpiece 11 is imaged by the camera 20 (step S1).

[0083] The image 40 of the workpiece 11 acquired by the camera 20 (see FIG. 3) is input to the control unit 24 (see FIG. 4). Then, the coordinate specifying unit 52 specifies a plurality of coordinates 74 (see FIG. 5) indicating the positions of the outer peripheral edge 11c of the workpiece 11 included in the image 40 (step S2). After that, the approximate line calculation unit 54 calculates an approximate line 76 (see FIG. 6) that approximates the outer peripheral edge 11c of the workpiece 11 based on the plurality of coordinates 74 specified by the coordinate specifying unit 52 (step S3).

[0084] Next, the outer peripheral edge determination unit 56 determines whether the approximate line 76 corresponds to the outer peripheral edge 11c of the workpiece 11 (step S4). For example, as described above, the outer peripheral edge determination unit 56 classifies the coordinates 74 into in-area coordinates and out-of-area coordinates based on the distance between the coordinates 74 and the approximate line 76, and determines the correspondence between the outer peripheral edge 11c of the workpiece 11 and the approximate line 76 based on whether the number or ratio of the in-area coordinates is within an allowable range.

[0085] If it is determined that the approximate line 76 corresponds to the outer peripheral edge 11c of the workpiece 11 (YES in step S5), the approximate line 76 is regarded as the same as the outer peripheral edge 11c of the workpiece 11, and the orientation of the workpiece 11 is specified based on the inclination of the approximate line 76. Then, the display control unit 58a outputs a control signal to the display unit 22 to display the image 40 on the display unit 22 (step S6).

[0086] Note that the display control unit 58a may also display other information (coordinates 74, approximate line 76, etc.) on the display unit 22 together with the image 40. Further, when there is a row or column including coordinates 74 (out-of-area coordinates) indicating positions outside a predetermined range from the approximate line 76, or when there is a row or column in which no pixel 70 having a brightness difference with an adjacent pixel 70 equal to or greater than a threshold value is detected, the display control unit 58a may display identification marks 78, 80A, 80B (see FIG. 7) on the display unit 22 together with the image 40. However, step S6 can also be omitted.

[0087] Next, the workpiece 11 is conveyed from the support unit 18 to the chuck table 26 (see FIG. 1) by the conveyance mechanism 28 (see FIG. 1) (step S7). At this time, the orientation of the workpiece 11 is adjusted based on the angle of the approximate line 76.

[0088] On the other hand, when it is determined that the approximate line 76 does not correspond to the outer peripheral edge 11c of the workpiece 11 (NO in step S5), the operation control unit 58 causes an error to be notified to the display unit 22 or the like (step S8). Further, the display control unit 58a outputs a control signal to the display unit 22, and causes the image 40 and the identification marks 78, 80A, 80B (see FIG. 7) to be displayed on the display unit 22 (step S9). At this time, the display control unit 58a may cause other information (coordinates 74, approximate line 76, etc.) to be displayed on the display unit 22 together with the image 40.

[0089] Then, the operator who has confirmed the error takes measures to eliminate the abnormality based on the information displayed on the display unit 22 (step S10). For example, when coordinates 74 (out-of-area coordinates) indicating a position outside a predetermined range from the approximate line 76 are detected, the operator checks whether there is a foreign object attached to the workpiece 11, and performs a cleaning process on the workpiece 11 as necessary. Further, for example, when there is a row or column in which no pixel 70 having a brightness difference from the adjacent pixel 70 equal to or greater than the threshold value is detected, the operator checks the illumination 32 (see FIGS. 2(A) and 2(B)), and replaces the light source 34 or the like as necessary.

[0090] The series of operations of the control unit 24 described above are realized by executing a program stored in the storage unit 60. Specifically, the storage unit 60 stores a program describing the processing in steps S1 to S9. Then, the control unit 24 reads out and executes the program from the storage unit 60 to automatically detect the orientation of the workpiece 11.

[0091] As described above, the orientation detection device 2 according to the present embodiment determines whether or not the approximate line 76 corresponds to the outer peripheral edge 11c of the workpiece 11 based on the distance between the plurality of coordinates 74 indicating the position of the outer peripheral edge 11c of the workpiece 11 and the approximate line 76 approximating the outer peripheral edge 11c of the workpiece 11. Thereby, it is possible to prevent the orientation of the workpiece 11 from being specified in a state where the outer peripheral edge 11c of the workpiece 11 is approximated by an inappropriate approximate line and the workpiece 11 from being conveyed in an inappropriate orientation.

[0092] In addition, the orientation detection device 2 can cause the display unit 22 to display identification marks 78, 80A, and 80B indicating positions where the coordinates 74 indicating the position of the outer peripheral edge 11c of the workpiece 11 are not appropriately specified. As a result, the operator is notified of the position where there is an abnormality in the detection of the outer peripheral edge 11c of the workpiece 11. As a result, the operator can immediately check the position where there is an abnormality in the detection of the outer peripheral edge 11c and take measures to promptly eliminate the abnormality.

[0093] Note that the structure, method, etc. according to the above embodiment can be appropriately changed and implemented without departing from the scope of the object of the present invention.

Explanation of Reference Numerals

[0094] 11 Workpiece 11a Front surface (first surface) 11b Back surface (second surface) 11c Outer peripheral edge (side surface) 2 Orientation detection device (orientation detection mechanism) 4 Base 4a, 4b Openings 6A, 6B Cassette stands 8 Cassette 10 Conveying mechanism (conveying unit) 12 Holding unit 12a Upper surface 12b Suction holes 14 Multi-joint arm 16 Detection unit 18 Support unit 20 Camera (imaging unit) 20a Imaging area (field of view) 22 Display unit (display unit, display device) 24 Control unit (control unit, control device) 26 Chuck table (holding table) 26a Holding surface 28 Conveyor mechanism (conveyor unit) 30 Support stand 30a Support surface 32 Lighting 34 Light source 36 Cover (case) 38 Diffusion plate 40 Image (captured image) 42 Outer peripheral edge region 50 Processing unit 52 Coordinate specifying unit 54 Approximation line calculation unit 56 Outer peripheral edge determination unit 58 Operation control unit 58a Display control unit 60 Memory unit 62 Coordinate memory unit 64 Approximation line memory unit 70 Pixel 72A Dark region 72B Bright region 72C Dark region 72D Intermediate region 74,74A Coordinates 76 Approximation line 78,80A,80B Identification marks

Claims

1. An orientation detection device for detecting the orientation of a non-circular workpiece, comprising: a support unit for supporting the workpiece; a camera for imaging the workpiece supported by the support unit to obtain an image including the outer peripheral edge of the workpiece; illumination for illuminating the workpiece supported by the support unit; a display unit; and a control unit, wherein the control unit calculates the brightness of a plurality of pixels included in the image along a direction intersecting the outer peripheral edge included in the image, and specifies coordinates of a plurality of pixels whose brightness difference from adjacent pixels is equal to or greater than a threshold value as a plurality of coordinates indicating the position of the outer peripheral edge as a coordinate specifying unit; an approximate line calculation unit for calculating an approximate line approximating the outer peripheral edge based on the plurality of coordinates; an outer peripheral edge determination unit for determining that the approximate line does not correspond to the outer peripheral edge of the workpiece when the number or ratio of the coordinates indicating positions within a predetermined range from the approximate line is outside the allowable range; and a display control unit for causing the display unit to display, together with the image, an identification mark indicating the position of a row or column including the coordinates indicating positions outside a predetermined range from the approximate line, or an identification mark indicating the position of a row or column not including pixels whose brightness difference from adjacent pixels is equal to or greater than a threshold value.

2. The orientation detection device according to claim 1, wherein the approximate line calculation unit calculates a straight line approximating the outer peripheral edge as the approximate line.

3. The orientation detection device according to claim 1 or 2, wherein the display control unit causes the display unit to display the identification mark so as not to overlap with the plurality of coordinates.

4. The orientation detection device according to any one of claims 1 to 3, wherein the display control unit causes the display unit to display, together with the image, a mark indicating that coordinates indicating positions outside a predetermined range from the approximate line have been detected, or a mark indicating that pixels whose brightness difference from adjacent pixels is equal to or greater than a threshold value have not been detected.

5. The orientation detection device according to any one of claims 1 to 4, wherein the identification mark is constituted by a color, a number, a character, a figure, a pattern, or a combination thereof.

Images