JP2007033202A - Visual inspection apparatus and visual inspection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a visual inspection apparatus and a visual inspection method, capable of accurately inspecting an object to be inspected which is held by other plate-like member. <P>SOLUTION: A holding section of the visual inspection apparatus places the object to be inspected so as to support it by at least three leading ends. A driving section moves the leading ends of the holding section up and down, respectively. A photographing means photographs the object to be inspected which is placed by the holding section. A relative movement means relatively moves at least one of the holding section and the photographing means. A detecting means detects distances between the photographing means and the object to be inspected which is placed by the holding section, along lines of sight of the photographing means with respect to a plurality of positions of the object to be inspected. A controller section controls the operation of the driving section from respective distances detected by the detecting means and moves the leading ends of the holding section up and down respectively such that those distances satisfy a prescribed condition. An automatic focusing means controls upper and lower positions of the photographing means, thereby focusing the photographing means on the object to be inspected which is placed by the holding section. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an appearance inspection apparatus and an appearance inspection method, and more specifically to an appearance inspection apparatus and an appearance inspection method for inspecting an appearance by imaging a thin plate member such as a glass mask or a film mask with a camera.

  A mask may be used when a pattern such as a conductor wiring is formed on the surface of a printed circuit board or the like on which an electronic component or the like is mounted. The mask is made of glass, film, or the like (hereinafter, a film mask is described as a representative thereof), and serves as an original pattern to be transferred to the substrate. Then, using a visual inspection apparatus, the visual inspection is performed for the presence or absence of defects in the wiring pattern formed on the film mask. For example, the film mask is placed on the stage surface of the appearance inspection apparatus with the surface on which the pattern is formed as the upper surface. The appearance inspection apparatus has an imaging camera such as a CCD (Charged Coupled Device) camera in a space on a film mask placed on a stage surface. The appearance inspection apparatus moves the stage surface horizontally in the main scanning direction, and images the film mask that has passed under the imaging camera. The visual inspection apparatus sequentially shifts the imaging camera in the sub-scanning direction every time scanning in the main scanning direction is completed, and finally captures the entire inspection area of the film mask to obtain image data. Thereafter, the appearance inspection apparatus performs a pattern matching process or the like on the obtained image data to detect a pattern defect.

  In an appearance inspection apparatus using such a film mask as an inspection object, in order to increase the accuracy of detecting a pattern defect, it is important that the focus of an imaging camera serving as an imaging unit coincides with the upper surface of the inspection object. . This becomes more prominent as the inspection resolution increases, and generally, a technique is used in which an imaging camera having an autofocus function is used to inspect while focusing on the upper surface of the inspection object in real time. For example, the autofocus method is premised on non-contact with the object to be inspected, and uses the information on the height of the object to be inspected obtained using a laser displacement sensor or the amount of blur of the captured image itself. The focus is adjusted.

An apparatus that changes the focal position of an imaging camera using information on the height and shape of an object to be inspected is disclosed (for example, see Patent Documents 1 to 3). The appearance inspection apparatus disclosed in Patent Document 1 detects a height displacement amount of a reference surface of an inspection object by a height sensor during conveyance of the inspection object, and moves the imaging camera in a focal direction based on the displacement amount. Focus by moving relatively. The apparatus disclosed in Patent Document 2 captures images by changing the focus position based on a focus map created by detecting the shape of a sample. The defect inspection apparatus disclosed in Patent Document 3 detects height information of a plurality of points including two points sandwiching an imaging position on the surface of an inspection object, and focuses the imaging apparatus using the height information. . In this way, the height and shape of the inspection object placed on the stage surface before the inspection is measured, or the displacement of the inspection object is measured, and the imaging camera is moved up and down in the focal direction according to the measurement result. For example, a method of scanning the inspection object while optimally adjusting the focal length is employed.
JP 2000-266991 A JP 2002-42706 A Japanese Patent Laid-Open No. 2003-177101

  Here, in order to improve the resolution of the imaging system described above, it is necessary to increase the lens magnification of the imaging camera. However, increasing the lens magnification of the imaging camera decreases the depth of focus of the lens.

  On the other hand, in many cases, a manufacturer handles a film mask, a glass mask, or the like, which is an object to be inspected, so that it does not come into direct contact with other objects during the production thereof. Therefore, an object to be inspected may be held and handled by a plate-like member (holding plate) such as an acrylic plate. For example, the film mask is held in contact with the main surface of the holding plate. The glass mask is held by being fitted into the opening of the frame-shaped holding plate. For such a holding plate, a material having a relatively high hardness with respect to the object to be inspected is used, but there are cases where precise flatness and parallelism between the lower surface and the upper surface are not guaranteed. Even if such a holding plate for holding the object to be inspected is placed on the stage surface of the appearance inspection apparatus, the holding plate and the stage surface do not contact each other, and the holding plate does not follow the stage surface. That is, the holding plate placed with respect to the stage surface of the appearance inspection apparatus may be inclined, and may be inclined more than the depth of focus described above. In such a case, in the image in which the imaging camera images the object to be inspected at a certain timing, a part of the image (for example, a gazing point) is focused, but the other in the image deviates from the depth of focus range. It will be in the state which cannot be focused on this part.

  Therefore, an object of the present invention is to provide an appearance inspection apparatus and an appearance inspection method that can accurately inspect an object to be inspected held by another plate-like member.

In order to achieve the above object, the present invention has the following features.
1st invention is the external appearance inspection apparatus which images and inspects to-be-inspected object. The appearance inspection apparatus includes a holding unit, a drive unit, an imaging unit, a relative movement unit, a detection unit, a control unit, and an autofocus unit. The holding unit supports the object to be inspected by at least three tips and places the object to be inspected. The drive unit moves the tip of the holding unit up and down. The imaging means images the inspection object placed on the holding unit. The relative movement unit relatively moves at least one of the holding unit and the imaging unit. The detecting means detects the line-of-sight direction distance of the imaging means from the imaging means to the inspection object placed on the holding unit with respect to a plurality of positions of the inspection object. The control unit controls the operation of the drive unit based on the distances detected by the detection unit, and moves the tip of the holding unit up and down so that the distances satisfy a predetermined condition. When the relative movement means relatively moves at least one of the holding unit and the imaging unit, the autofocus unit controls the vertical position of the imaging unit and the focus of the imaging unit is placed on the holding unit. Match with things.

  In a second aspect based on the first aspect, the detection means detects the distance with respect to three positions on the inspection object. The control unit moves the tip of the holding unit up and down so that the distances to the three positions are equal to each other.

  In a third aspect based on the first aspect, the detection means detects a distance with respect to three or more positions on the inspection object. The control unit moves the tip of the holding unit up and down so that the distances to all positions on the inspection object detected by the detection unit are within a predetermined range.

  In a fourth aspect based on the first aspect, the object to be inspected is held by a flat holding plate. The holding unit supports the lower surface of the holding plate with at least three tips.

  In a fifth aspect based on the fourth aspect, the plurality of positions at which the detection means detects the distance includes a position on the object to be inspected that is closest to a position where the holding plate is supported by the tip of the holding portion.

  In a sixth aspect based on the first aspect, the object to be inspected is held by a flat holding plate. The holding unit supports the lower surface of the holding plate with four tips.

  In a seventh aspect based on the sixth aspect, the plurality of positions at which the detecting means detects the distance is a position on the object to be inspected that is closest to two adjacent positions where the holding plate is supported by the tip of the holding portion. The holding plate is set to the position on the inspection object closest to the midpoint of the other two positions where the holding plate is supported by the tip of the holding portion.

  In an eighth aspect based on the first aspect, the appearance inspection apparatus further includes a fixed frame having a mounting surface on which an object to be inspected is formed. The holding portion is disposed inside the fixed frame.

  A ninth invention is an appearance inspection method for imaging and inspecting an inspection object using an imaging unit. The appearance inspection method includes a holding step, a detection step, a control step, and an autofocus step. In the holding step, the inspection object is supported by at least three tips, and the inspection object is placed. In the detection step, the line-of-sight direction distance of the imaging unit from the imaging unit to the inspection object placed at the tip is detected with respect to a plurality of positions of the inspection object. The control step moves the tip up and down based on the distances detected in the detection step so that the distances satisfy a predetermined condition. In the autofocus step, after the distance satisfies a predetermined condition, an image of the imaging unit is focused on the inspection object while relatively moving at least one of the inspection object and the imaging unit.

  In a tenth aspect based on the ninth aspect, the detecting step includes a step of detecting a distance with respect to three positions on the inspection object. The control step includes a step of moving the tip up and down so that the distances to the three positions are equal to each other.

  In an eleventh aspect based on the ninth aspect, the detecting step includes a step of detecting a distance with respect to three or more positions on the inspection object. The control step includes a step of moving the tip up and down so that the distances to all positions on the object detected in the detection step are within a predetermined range.

  According to the first aspect, the inclination of the inspection object placed on the holding unit with respect to the imaging unit can be controlled. For example, even if an image is obtained by imaging an inspection object with poor planar accuracy at a timing when the imaging means is present, the entire range can be accommodated within the depth of focus range of the imaging means. Therefore, an image in which the focus of the imaging means is matched with the upper surface of the object to be inspected in the entire range can be obtained, so that an accurate appearance inspection can be performed using the image.

  According to the second aspect of the invention, since the three points on the inspected object placed on the holding unit with respect to the imaging unit are controlled to have the same viewpoint direction distance, the plane including the three points is The object to be inspected can be placed perpendicular to the viewpoint direction with a small number of detection positions.

  According to the third aspect of the invention, since three or more points on the inspected object placed on the holding unit with respect to the imaging unit are controlled so as to have a viewpoint direction distance within a predetermined range, the line-of-sight direction It is possible to control the parallelism of the inspection object with respect to a plane perpendicular to the plane.

  According to the fourth aspect of the present invention, even when the object to be inspected is handled by being held by the holding plate whose precise flatness and parallelism between the lower surface and the upper surface are not guaranteed, the state of being held by the holding plate It is possible to control the inclination of the inspection object. For example, even if an image is obtained by capturing an object to be inspected held on a holding plate whose parallelism on the upper surface is poor with respect to the lower surface, at a certain timing, the entire range is within the depth of focus range of the imaging device. Can do.

  According to the fifth aspect, since the position for moving the inspection object up and down and the position for detecting the distance are close to each other, it is possible to easily predict a change in the distance according to the vertical movement.

  According to the sixth aspect of the invention, it is possible to prevent the end of the holding plate from sagging due to its own weight, which is expected by supporting the holding plate at three points.

  According to the seventh aspect, since the detection position is set at a position on the inspection object closest to the two positions supported by the tips, the tips supporting the two positions are always set to the same adjustment length. It is possible to control the distance of the detection position by moving it up and down in the same direction, thereby preventing one of the four tips and the holding plate from coming into contact with each other and making the placement unstable. .

  According to the eighth aspect of the invention, when imaging an object to be inspected and held on a glass table or the like that is guaranteed flatness and parallelism, the placement surface is formed perpendicular to the line-of-sight direction of the imaging means. Thus, the inspection object can be imaged by placing the glass table on the upper surface of the fixed frame. That is, an optimal placement method can be selected according to the form of the inspection object.

  Further, according to the appearance inspection method of the present invention, the same effect as the above-described appearance inspection apparatus can be obtained.

  An appearance inspection apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a top view and a front view schematically showing the overall configuration of the appearance inspection apparatus. Here, for the sake of specific explanation, a case where a film mask on which a wiring pattern is drawn is inspected as an object to be inspected will be described as an example. The present invention is not limited to a film mask, but is effective for inspection using a thin plate-like member such as a glass mask, a printed board, and a flexible thin board as an inspection object. Further, as an example of a further inspection object, a case where a film mask, which is an example of the inspection object, is held and handled by a plate-like member (holding plate) such as an acrylic plate will be described. For example, the film mask is held in contact with the main surface of the holding plate. In the case of a glass mask, the glass mask is fitted and held in the opening of the frame-shaped holding plate.

  In FIG. 1, an appearance inspection apparatus 1 generally includes a stage transport mechanism unit 2, an imaging mechanism unit 3, and a control unit 4 (see FIG. 2). The stage transport mechanism unit 2 includes a stage unit 21, a turning unit 22, a Y-axis direction drive mechanism 23, a base unit 24, and an inclination adjustment mechanism 25. The imaging mechanism unit 3 includes an imaging camera 31, a support member 32, an X-axis direction drive member 33, a camera support member 34, an X-axis direction drive mechanism 35, a Z-axis direction drive mechanism 36, and a height detection sensor 37. .

  The stage portion 21 has a frame fixed to the entire circumference on the one main surface of the planar member. A plurality of inclination adjusting mechanisms 25 are installed inside the frame on the planar member. As will be apparent from the description below, the holding plate that holds the film mask is placed on the plurality of tilt adjusting mechanisms 25. Here, as an example, four tilt adjustment mechanisms 25 a to 25 d are installed in the stage unit 21. When the four tilt adjustment mechanisms 25a to 25d are described generically, the tilt adjustment mechanism is described with reference numeral 25. Here, the inclination adjustment mechanism 25 includes an inclination adjustment motor 251, an inclination adjustment driver 252, and an inclination adjustment holding pin 253 described later (see FIGS. 2 and 3). The holding unit of the present invention corresponds to the tilt adjustment holding pin 253 and the like. The vertical drive means of the present invention corresponds to a tilt adjustment motor 251 and a tilt adjustment driver 252 and the like.

  The other principal surface of the planar member of the stage unit 21 is supported by the turning unit 22, and the stage unit 21 is configured to be rotatable in the θ direction shown in the figure by the turning operation of the turning unit 22. The base portion 24 is extended and fixed in the illustrated Y-axis direction parallel to the stage surface so as to pass below the imaging mechanism portion 3. The Y-axis direction drive mechanism 23 slides along a guide provided in the Y-axis direction on the upper surface of the base portion 24, and the turning portion 22 is fixed on the upper surface thereof. The Y-axis direction drive mechanism 23 includes a Y-axis drive motor 231 and a Y-axis NC driver 232 described later (see FIG. 2). As a result, the Y-axis direction drive mechanism 23 can be moved in the Y-axis direction (main scanning direction) along the guide of the base portion 24 by the driving force from the Y-axis drive motor 231 and supported by the turning portion 22. The horizontal movement of the stage unit 21 in the main scanning direction is also possible. The stage transport mechanism unit 2 includes a transmission illumination light source (not shown) below the holding plate placed on the tilt adjustment mechanisms 25a to 25d. This light source for transmitted illumination irradiates the lower surface of the film mask with illumination light through a holding plate.

  The support member 32 is installed in the upper space of the stage unit 21 that horizontally moves on the base unit 24. An X-axis direction drive mechanism 35 is provided on the support member 32, and the X-axis direction drive member 33 is parallel to the stage surface and in the illustrated X-axis direction (sub-scanning direction) perpendicular to the Y-axis direction. Move. Note that the X-axis direction drive mechanism 35 includes an X-axis drive motor 351 and an X-axis NC driver 352 described later (see FIG. 2). The X-axis direction drive member 33 is provided with a Z-axis direction drive mechanism 36, and moves the camera support member 34 in the illustrated Z-axis direction perpendicular to the X-axis and Y-axis directions. The Z-axis direction drive mechanism 36 includes a Z-axis drive motor 361 and a Z-axis NC driver 362 described later (see FIG. 2).

  The imaging camera 31 is composed of, for example, a CCD camera, and is supported by the camera support member 34 so that the line-of-sight direction (imaging direction) is the downward direction of the Z axis in the figure. The imaging camera 31 converts incident light into an electric signal indicating its color and intensity. In the example of the appearance inspection apparatus 1 shown in FIG. 1, two imaging cameras 31a and 31b are provided, and are supported by a camera support member 34 so that their line-of-sight directions are in the downward direction of the Z axis in the drawing. For example, the imaging camera 31a for obtaining image data for pattern matching processing in the appearance inspection apparatus 1 and the imaging camera 31b for obtaining image data for visual inspection by the user of the appearance inspection apparatus 1 are configured. The transmitted light irradiated to the film mask from the light source for transmitted illumination is received. In the present invention, a plurality of imaging cameras 31 may be fixed to the camera support member 34, or only one imaging camera 31 may be fixed to the camera support member 34.

  With such a configuration, the imaging camera 31 is movable in the illustrated X-axis direction (sub-scanning direction) and Z-axis direction (line-of-sight direction). Then, main scanning is performed by moving the stage unit 21 in the main scanning direction (Y-axis direction) while the position of the imaging camera 31 in the X-axis direction is fixed. Next, every time main scanning from one end to the other end of the inspection area of the film mask is completed, the imaging camera 31 moves by a predetermined distance along the sub-scanning direction (X-axis direction). As a result, image data for the entire inspection area of the film mask is obtained from the imaging camera 31. Furthermore, the imaging camera 31 can be moved in the Z-axis direction (line-of-sight direction) by the Z-axis direction drive mechanism 36. As will be described later, the Z-axis direction drive mechanism 36 moves the camera support member 34 in the Z-axis direction according to the height in the Z-axis direction of the film mask (inspection object) detected by the height detection sensor 37. By appropriately moving, the autofocus of the imaging camera 31 is realized. That is, according to the height data in the Z-axis direction detected by the height detection sensor 37, the Z-axis direction drive mechanism 36 always has the focus position of the imaging camera 31 on the upper surface of the film mask while scanning the film mask. In this way, the position of the imaging camera 31 in the Z-axis direction is controlled. The relative movement means of the present invention corresponds to the X-axis direction drive mechanism 35 and the Y-axis direction drive mechanism 23.

  The height detection sensor 37 is respectively applied to predetermined inclination measurement points set on the film mask held on the holding plate placed on the inclination adjusting mechanisms 25a to 25d before the imaging operation described later. (The distance from the height detection sensor 37 to the measurement point) is detected. Also, during the imaging operation, the height to the film mask is sequentially detected in accordance with the imaging location for autofocusing of the imaging cameras 31a and 31b. For example, the height detection sensor 37 is a laser displacement sensor, an optical displacement sensor, an ultrasonic sensor, or the like. The height detection sensor 37 is fixed to the imaging camera 31 and the camera support member 34 with the height detection direction being the Z-axis direction toward the upper surface of the stage unit 21 in the same manner as the line-of-sight direction of the imaging camera 31. As will be apparent from the description below, the height detection sensor 37 detects the height of the object to be inspected in the Z-axis direction. If the height can be detected while being movable in the direction, it may be fixed to another part.

  Next, with reference to FIG. 2, a schematic configuration of the control function in the appearance inspection apparatus 1 will be described. FIG. 2 is a block diagram showing the control function of the appearance inspection apparatus 1.

  In FIG. 2, the appearance inspection apparatus 1 includes a control unit 4 including a main control unit 41, a focus control unit 42, and a storage unit 43. The main control unit 41 and the focus control unit 42 are constituted by, for example, a CPU board and are connected to each other. A storage unit 43 is connected to the main control unit 41 and the focus control unit 42. The storage unit 43 is used as a storage area when the main control unit 41 and the focus control unit 42 perform processing, and stores a data group necessary for processing. The storage unit 43 stores a height table 431.

  The main control unit 41 mainly controls operations of the X-axis NC driver 352 and the focus control unit 42. The X-axis NC driver 352 drives the X-axis drive motor 351 according to the control of the main control unit 41. The X-axis drive motor 351 moves the X-axis direction drive member 33 in the X-axis direction (sub-scanning direction; see FIG. 1), and moves the imaging camera 31 and the height detection sensor 37 in the X-axis direction. With these configurations, the main control unit 41 can control the operations of the imaging camera 31 and the height detection sensor 37 in the sub-scanning direction.

  The focus control unit 42 mainly controls the operations of the Y-axis NC driver 232, the Z-axis NC driver 362, and the tilt adjustment drivers 252a to 252d. The Y-axis NC driver 232 drives the Y-axis drive motor 231 according to the control of the focus control unit 42. The Y-axis drive motor 231 moves the stage unit 21 horizontally in the Y-axis direction (main scanning direction; see FIG. 1). With these configurations, the focus control unit 42 can control the operation of the stage unit 21 in the main scanning direction. The Z-axis NC driver 362 drives the Z-axis drive motor 361 according to the control of the focus control unit 42. Then, the Z-axis drive motor 361 moves the camera support member 34 in the Z-axis direction (line-of-sight direction; see FIG. 1), and causes the imaging camera 31 and the height detection sensor 37 to move in the Z-axis direction. With these configurations, the focus control unit 42 can control the operation of the imaging camera 31 with respect to the line-of-sight direction (focus direction).

  The inclination adjustment drivers 252a to 252d drive the inclination adjustment motors 251a to 251d according to the control of the focus control unit 42, respectively. Then, the inclination adjustment motors 251a to 251d move inclination adjustment holding pins 253a to 253d (described later) in the Z-axis direction, respectively. As will be described later, a holding plate for holding the film mask is placed on the upper end portion of the inclination adjustment holding pins 253a to 253d. With these configurations, the focus control unit 42 can hold the holding plate for the line of sight. Can be adjusted.

  Here, the main control unit 41 and the focus control unit 42 scan the inspection object in the X and Y axis directions before visual inspection of the inspection object, and create a height table 431 in advance, 43. When creating the height table 431, the height detection sensor 37 outputs the height information DL of the upper surface of the inspection object held on the holding plate to the focus control unit 42. The relative positional relationship between the height detection sensor 37 and the object to be inspected in the Y-axis direction is determined by outputting a feedback pulse PF output from the Y-axis drive motor 231 to the focus control unit 42. 42 can be detected. Further, the relative positional relationship between the height detection sensor 37 and the inspection object in the X-axis direction is obtained by obtaining a control amount for moving the X-axis direction driving member 33 in the X-axis direction from the main control unit 41. It can be detected by the control unit 42. In other words, the focus control unit 42 detects the height detection sensor 37 based on the relative positional relationship between the height detection sensor 37 and the inspection object held on the holding plate in the X-axis direction and the Y-axis direction. The position on the inspection object can be obtained. The focus control unit 42 can obtain the height information DL for the position on the inspection object detected by the height detection sensor 37.

  Next, the configuration of the tilt adjustment mechanism 25 will be described with reference to FIGS. 3 and 4. 3 is a view of the section ii of FIG. 1 as viewed from the j direction, and is a sectional view of the stage unit 21 showing a state in which the film mask F held by the holding plate Pa is placed on the stage unit 21. . Here, in order to clarify the difference between the stage unit 21 and other components, only the cross-section of the planar member and the frame of the stage unit 21 are indicated by hatched areas. FIG. 4 is a top view of the stage unit 21 showing a state in which the film mask F held on the holding plate Pa is placed on the stage unit 21.

  In FIG. 3, the inclination adjustment holding pins 253a to 253d are arranged so as to be movable up and down in the Z-axis direction by driving inclination adjustment motors 251a to 251d, respectively. The tilt adjustment holding pins 253a to 253d can be protruded / retracted from the uppermost position of the stage portion 21 (the uppermost position in the Z-axis direction of the frame body) according to the drive of the tilt adjustment motors 251a to 251d. It becomes. For example, the inclination adjustment motors 251a to 251d are configured by a stepping motor, a motor that drives a cam, or the like, and controls the vertical position of the inclination adjustment holding pins 253a to 253d according to their drive amounts. In addition, the tilt adjustment motors 251a to 251d may be other actuators such as piezoelectric elements that cause the tilt adjustment holding pins 253a to 253d to move up and down.

  On the other hand, the film mask F that is an object to be inspected is held at a substantially central position on the upper surface of the holding plate Pa. Then, the holding plate Pa is placed on the inclination adjustment holding pins 253a to 253d so that the upper end portions of the inclination adjustment holding pins 253a to 253d are in contact with the lower surface of the holding plate Pa. Here, even if the holding plate Pa is larger than the frame of the stage portion 21, the inclination adjusting holding pins 253a to 253d are protruded from the uppermost position of the stage portion 21, whereby the holding plate Pa is tilted and adjusted holding pins 253a. It can be placed on the appearance inspection apparatus 1 by contacting only the tip of ˜253d.

  In FIG. 4, the tilt adjustment mechanisms 25 a to 25 d are respectively fixed at predetermined positions in the frame body of the stage unit 21. For example, as shown in FIG. 4, the inclination adjusting mechanisms 25 a and 25 b are respectively installed at the corners on both ends of one side parallel to the X axis with respect to the rectangle inside the frame of the stage portion 21. The inclination adjusting mechanisms 25c and 25d are respectively installed at positions near the other side parallel to the X axis with respect to the rectangle. The inclination adjusting mechanisms 25c and 25d are installed closer to each other than the distance between the inclination adjusting mechanisms 25a and 25b installed at both end corners of one side (for example, a distance that divides the other side into three equal parts). .

  Here, the reason why the distance between the tilt adjusting mechanisms 25c and 25d is smaller than the distance between the tilt adjusting mechanisms 25a and 25b is that the tilt adjusting mechanisms 25c and 25d are brought close to each other while being supported at four points. This is in order to give a pseudo-supporting effect at three points. That is, in theory, three points are ideal for controlling the inclination of one plane. However, if one side of the holding plate Pa holding the film mask F is supported by only one point in the middle, the two sides hang down. It can happen. On the other hand, when the four corners of the holding plate Pa are supported at four points, the floating plate is lifted at any one point due to distortion of the holding plate Pa or the like. That is, there is a possibility that the holding plate Pa and the tilt adjusting mechanism are separated from each other and the tilt adjustment becomes impossible. For this reason, in the above-described embodiment, two of the four tilt adjusting mechanisms are brought close to each other so that the holding plate Pa and the tilt adjusting mechanism are not separated as much as possible and the holding plate Pa is supported. By using four points, the drooping of both ends is prevented.

  Next, an inclination measurement point for measuring the height using the above-described height detection sensor 37 will be described. At least three tilt measurement points are set on the film mask F. Preferably, the tilt measurement point is set at a position on the film mask F closest to the region where the tilt adjustment holding pins 253a to 253d and the holding plate Pa are in contact with each other. For example, when three inclination measurement points are set for the inclination adjustment mechanisms 25a to 25d installed at the positions as described above, the inclination adjustment mechanisms 25a and 25b installed at both end corners of one side are closest. Tilt measurement points ha and hb are set at positions on the film mask F, respectively. Then, an inclination measurement point hm is set at a position on the film mask F closest to the midpoint M between the inclination adjustment mechanisms 25c and 25d. Thus, by setting the tilt measurement point in the vicinity of the tilt adjustment mechanism 25 that can move up and down, a change in the tilt measurement point according to the vertical movement of each tilt adjustment holding pin 253 can be easily predicted. These inclination measurement points may be described as measurement positions in the height table 431 of the storage unit 43 by setting their positions in advance according to the shape of the inspection object.

  FIG. 4 shows an example in which the film mask F is not held on the area where the tilt adjustment holding pins 253a to 253d and the holding plate Pa are in contact, but the film mask F is held on the area. If there is, the tilt measurement point may be set on the region and the midpoint M. In addition, if the effect of easily predicting the change in the tilt measurement point described above is not expected, the tilt measurement point may be set in addition to these setting examples. For example, four or more tilt measurement points may be set on the film mask F, or may be set at positions away from the tilt adjustment mechanism 25.

  Next, with reference to FIG. 5 to FIG. 7, an operation for inspecting the appearance of the film mask F held on the holding plate Pa using the appearance inspection apparatus 1 will be described. FIG. 5 is a flowchart showing an operation of inspecting the appearance using the appearance inspection apparatus 1. FIG. 6 is a front view showing an example of the operation of the height detection sensor 37. FIG. 7 is a front view showing an example of the operation of the tilt adjustment mechanism 25.

  In FIG. 5, the user of the appearance inspection apparatus 1 contacts the film mask F held on the holding plate Pa with the upper end portion of each of the inclination adjustment holding pins 253 a to 253 d to be in a predetermined position with respect to the stage portion 21. (Step S91; see FIGS. 3 and 4). Here, when the holding plate Pa is placed, the stage transport mechanism unit 2 is horizontally moved to a position deviated from the space immediately below the imaging mechanism unit 3. Thereby, it is possible to perform an operation of supplying the inspection object to the appearance inspection apparatus 1 without the imaging mechanism unit 3 and the holding plate Pa contacting each other.

  Next, the appearance inspection apparatus 1 detects the distance to the tilt measurement point using the height detection sensor 37, and describes the measurement result in the height table 431 according to the position (step S92). In FIG. 6, the height detection sensor 37 detects the distance L for each inclination measurement point set on the film mask F, and outputs the height information DL. Here, the operation of moving the height detection sensor 37 onto each set inclination measurement point is performed by the main control unit 41 and the focus control unit 42 controlling the X-axis NC driver 352 and the Y-axis NC driver 232, respectively. Done. That is, the position of the height detection sensor 37 is fixed in the Z-axis direction. As described above, the height detection sensor 37 and the film mask F move relative to each other in the X and Y axis directions under the control of the main control unit 41 and the focus control unit 42, so The height detection sensor 37 moves (arrow S in the figure). Note that the distance L detected by the height detection sensor 37 may not be an absolute distance, and may be a relative distance with respect to a preset reference distance.

  Next, the appearance inspection apparatus 1 refers to the height table 431, and shows the tilt adjustment holding pin 253 of the tilt adjustment mechanism 25 so that the distance L at each tilt measurement point satisfies the set condition. Each is moved up and down in the direction (step S93).

  A first example of the setting condition is to make all the distances L at each inclination measurement point equal. For example, when the three inclination measurement points ha, hb, and hm shown in FIG. 4 are set, the inclination adjustment mechanisms 25a to 25d so that the distances L at the inclination measurement points ha, hb, and hm are all the same. Move up and down. Specifically, the focus control unit 42 controls the inclination adjustment driver 252a to drive the inclination adjustment motor 251a to move the inclination adjustment holding pin 253a up and down in order to adjust the distance L of the inclination measurement point ha. In addition, the focus control unit 42 controls the inclination adjustment driver 252b to drive the inclination adjustment motor 251b to move the inclination adjustment holding pin 253b up and down in order to adjust the distance L of the inclination measurement point hb. Further, the focus control unit 42 controls the tilt adjustment drivers 252c and 252d to drive the tilt adjustment motors 251c and 251d and move the tilt adjustment holding pins 253c and 253d up and down in order to adjust the distance L of the tilt measurement point hm. Move. Here, the focus control unit 42 sets the tilt adjustment holding pins 253c and 253d because the tilt measurement point hm is set to the position on the film mask F that is closest to the midpoint M between the tilt adjustment mechanisms 25c and 25d. Always move the same adjustment length up and down in the same direction. Thereby, one of the four inclination adjustment holding pins 253a to 253d and the holding plate Pa are not in contact with each other, and it is possible to prevent the placement from becoming unstable.

  A second example of the setting condition is to set the distance L at each inclination measurement point within a predetermined range. For example, when four or more inclination measurement points are set on the film mask F, it is difficult to make all the distances L equal unless the flatness of the holding plate Pa is high. However, a large number of inclination measurement points are set on the entire surface of the film mask F, and the distance L at these inclination measurement points is adjusted within a predetermined range (that is, the difference between the maximum value and the minimum value of the distance L is set as a range). The degree of parallelism of the film mask F with respect to the XY plane can be controlled. Even in the case of using the second example, the focus control unit 42 always moves the tilt adjustment holding pins 253c and 253d up and down in the same direction by the same adjustment length, so that the four tilt adjustment holding pins 253a to 253d are moved. One and the holding plate Pa are not in contact with each other, and the mounting is prevented from becoming unstable.

  Next, the appearance inspection apparatus 1 images the film mask F held on the holding plate Pa placed on the tilt adjustment mechanism 25 by the imaging camera 31 (step S94). Hereinafter, the imaging procedure by the imaging camera 31 will be described in detail.

  As described above, the imaging camera 31 is movable in the X-axis direction (sub-scanning direction) and the Z-axis direction (line-of-sight direction) (see FIG. 1). Then, main scanning is performed by moving the stage unit 21 in the main scanning direction (Y-axis direction) while the position of the imaging camera 31 in the X-axis direction is fixed. For example, the focus control unit 42 controls the Z-axis direction drive mechanism 36 so that the imaging camera 31 is focused on a predetermined position of the film mask F placed on the tilt adjustment mechanism 25, and when the focus is achieved. The distance obtained from the height information DL output from the height detection sensor 37 is a reference distance. Since this reference distance is a fixed value unless the magnification of the imaging camera 31 is changed, the reference distance may be set as a default value and stored in the storage unit 43 in advance.

  Next, while scanning the film mask F, the focus control unit 42 controls the distance between the film mask F located immediately below the height detection sensor 37 in the Z-axis direction and the height detection sensor 37 to be the reference distance. The Z-axis direction drive mechanism 36 is controlled to move the position of the imaging camera 31 in the Z-axis direction. As a result, the position of the imaging camera 31 in the Z-axis direction is controlled so that the focal position of the imaging camera 31 is always on the upper surface of the film mask F, and the autofocus during scanning in the XY axis direction of the film mask F is performed. Realized.

  Next, the main control unit 41 controls the X-axis direction driving mechanism 35 to move the imaging camera 31 in the sub-scanning direction (X-axis) every time main scanning from one end to the other end of the inspection area of the film mask F is completed. (Direction) along a predetermined distance. Then, the focus control unit 42 performs scanning by moving the stage unit 21 in the Y-axis direction opposite to the previous time while the position of the imaging camera 31 in the X-axis direction is fixed. Also at this time, the focus control unit 42 is configured so that the distance between the film mask F positioned immediately below the height detection sensor 37 in the Z-axis direction and the height detection sensor 37 becomes the reference distance. The axial drive mechanism 36 is controlled to move the position of the imaging camera 31 in the Z-axis direction. By repeating such an operation, while scanning the film mask F, the position of the imaging camera 31 in the Z-axis direction is controlled so that the focal position of the imaging camera 31 is always on the upper surface of the film mask F. The image data of the entire inspection area is output from the imaging camera 31.

  Thus, the appearance inspection apparatus 1 of the present invention can control the inclination of the inspection object held on the holding plate with respect to the imaging camera 31. For example, even if an object to be inspected is manufactured using a holding plate for which precise flatness or parallelism between the lower surface and the upper surface is not guaranteed, the inclination of the object to be inspected while being held by the holding plate Can be controlled. In addition, even if the image is obtained by capturing the inspection object held by the holding plate with the lower parallelism of the upper surface with respect to the lower surface at a certain timing, the entire range is within the depth of focus range of the imaging camera 31. Can fit. Accordingly, an image in which the focus of the imaging camera is matched with the upper surface of the object to be inspected in the entire range can be obtained, so that an accurate appearance inspection can be performed using the image.

  Moreover, since a stage (table) whose position has been precisely adjusted in advance is not required for placing the inspection object in the appearance inspection apparatus 1, the cost of the appearance inspection apparatus 1 itself can be reduced. If such cost reduction effect is not expected, imaging may be performed by placing the inspection object on the frame of the stage unit 21 according to the form of the inspection object. In this case, the upper surface of the frame body of the stage unit 21 is formed with a processing accuracy equal to or less than a predetermined flatness, and the tilt with respect to the imaging camera 31 is adjusted and installed. For example, when imaging an object to be inspected and held in close contact with a glass table or the like that is guaranteed flatness and parallelism, the glass table is placed on the upper surface of the frame body of the stage unit 21 as described above, so that It is also possible to image the inspected object.

  Further, even when the inspection object is imaged by placing a glass table on which the inspection object is closely held on the upper surface of the frame body of the stage portion 21 described above, the inclination adjustment described above may be performed. For example, after placing a glass table with the object to be intimately held on the upper surface of the frame, the distance L (see FIG. 6) with respect to the tilt measurement point set on the object to be inspected is detected. And when those distance L contains the dispersion | variation on the predetermined range, the inclination adjustment holding pin 253 of the inclination adjustment mechanism 25 is raised to the position which protrudes from a frame body upper surface. As a result, the glass table is placed in contact with the upper end portion of the tilt adjustment holding pin 253, so that tilt adjustment similar to that of the holding plate Pa described above is possible.

  Further, the distance L to the tilt measurement point may be detected again after the operation of step S93. For example, when it is difficult to predict a change according to the vertical movement of the tilt adjusting mechanism 25, the tilt of the object to be inspected held on the holding plate Pa is guaranteed by checking the adjusted distance L, and further adjustment is required. In such a case, the same adjustment can be repeated.

  In the above description, the four tilt adjustment mechanisms 25 a to 25 d are installed on the stage unit 21. Thereby, it is possible to prevent the end portions of the holding plate Pa placed on the inclination adjusting mechanism 25 (for example, the upper right corner portion and the upper left corner portion of the holding plate Pa shown in FIG. 4) from hanging down due to their own weight. . If such an effect is not expected, or if the holding plate itself has sufficient rigidity to prevent the sagging, three tilt adjustment mechanisms may be installed on the stage portion 21. In this case, the two tilt adjusting mechanisms are disposed at the same positions (see FIG. 4) as the tilt adjusting mechanisms 25a and 25b. In addition, one inclination adjusting mechanism is arranged in the vicinity of the middle point of the other side where the other two inclination adjusting mechanisms are disposed (for example, the middle point M shown in FIG. Position). In this way, by limiting the number of installed tilt adjustment mechanisms, it becomes possible to ensure contact with the holding plate placed on them, and the tilt according to the vertical movement of each tilt adjustment holding pin Changes in measurement points can be easily predicted.

  In the case where such an effect is not expected, it goes without saying that the present invention can be realized even if five or more tilt adjustment mechanisms are installed in the stage portion 21. Further, even when five or more tilt adjustment mechanisms are installed in the stage unit 21, four (or three) tilt adjustment mechanisms to be contacted are selected according to the size of the holding plate that holds the object to be inspected. Is also possible.

  Even if the object to be inspected is held on a holding plate having a small size, the present invention can be realized by the above-described four inclination adjusting mechanisms 25a to 25d on the stage portion 21. For example, a plate-like member (for example, a glass table) that can come into contact with all the tip portions of the four inclination adjustment holding pins 253a to 253d is prepared separately. And if the said plate-shaped member is mounted on the inclination adjustment holding | maintenance pin 253a-253d and the small size holding plate holding the to-be-inspected object is arrange | positioned on the upper surface, the inclination of the said holding plate will be four inclination adjustment mechanisms. It can be adjusted by 25a to 25d.

  In the above description, the example in which the imaging camera 31 receives the transmitted light irradiated to the object to be inspected from the transmitted illumination light source provided below the holding plate Pa has been described. May be provided. In this case, the imaging camera 31 receives the reflected light reflected by the object to be inspected from the light source provided above the holding plate Pa.

  In the present embodiment, the main scanning is performed by moving the stage unit 21 in the Y-axis direction. However, the present invention is not limited to this, and the main scanning is performed by moving the imaging camera 31 in the main scanning direction. You may do it. Similarly, instead of moving the imaging camera 31 in the sub-scanning direction, the stage unit 21 may be moved in the sub-scanning direction.

  The appearance inspection apparatus and method according to the present invention can perform inspection with high accuracy, and are useful as an appearance inspection apparatus and an appearance inspection method for inspecting appearance of a thin plate-like member held on a holding plate or the like as an inspection object. It is.

The top view and front view which show typically the whole structure of the external appearance inspection apparatus which concerns on one Embodiment of this invention The block diagram which shows the control function of the external appearance inspection apparatus 1 of FIG. FIG. 1 is a cross-sectional view of the stage portion 21 on which the film mask F held on the holding plate Pa is placed as seen from the j direction in FIG. A top view of the stage unit 21 on which the film mask F held on the holding plate Pa is placed. Flowchart showing an operation for visual inspection using the visual inspection apparatus 1 Front view showing an example of the operation of the height detection sensor 37 Front view showing an example of the operation of the tilt adjustment mechanism 25

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Appearance inspection apparatus 2 ... Stage conveyance mechanism part 21 ... Stage part 22 ... Turning part 23 ... Y-axis direction drive mechanism 231 ... Y-axis drive motor 232 ... Y-axis NC driver 24 ... Base part 25 ... Inclination adjustment mechanism 251 ... Inclination Adjustment motor 252... Tilt adjustment driver 253... Tilt adjustment holding pin 3... Imaging mechanism 31 .. imaging camera 32 .. support member 33 .. X-axis direction drive member 34. Motor 352 ... X-axis NC driver 36 ... Z-axis direction drive mechanism 361 ... Z-axis drive motor 362 ... Z-axis NC driver 37 ... Height detection sensor 4 ... Control unit 41 ... Main control unit 42 ... Focus control unit 43 ... Storage unit 431 ... Height table

Claims (11)

An appearance inspection apparatus for imaging and inspecting an inspection object,
A holding unit for supporting the object to be inspected by at least three tips and placing the object to be inspected;
A drive unit for vertically moving the tip of the holding unit;
Imaging means for imaging an object to be inspected placed on the holding unit;
Relative movement means for relatively moving at least one of the holding unit and the imaging means;
Detecting means for detecting a visual direction distance of the imaging means from the imaging means to the inspection object placed on the holding unit with respect to a plurality of positions of the inspection object;
A control unit that controls the operation of the drive unit based on each distance detected by the detection unit, and moves the tip of the holding unit up and down so that the distance satisfies a predetermined condition;
When the relative moving means relatively moves at least one of the holding unit and the imaging unit, the vertical position of the imaging unit is controlled to focus the imaging unit on the holding unit. And an auto-inspection device for adjusting the appearance. The detection means detects the distance with respect to three positions on the inspection object,
The appearance inspection apparatus according to claim 1, wherein the control unit moves the tip of the holding unit up and down so that the distances to the three positions are equal to each other. The detection means detects the distance with respect to three or more positions on the inspection object,
The control unit moves the tip of the holding unit up and down so that the distances to all the positions on the inspection object detected by the detection unit are within a predetermined range, respectively. Item 1. An appearance inspection apparatus according to Item 1. The inspection object is held by a flat holding plate,
The appearance inspection apparatus according to claim 1, wherein the holding unit supports the lower surface of the holding plate with at least three tips.   5. The external appearance according to claim 4, wherein the plurality of positions at which the detection unit detects the distance includes a position on the inspection object closest to a position at which the holding plate is supported by a tip of the holding unit. Inspection device. The inspection object is held by a flat holding plate,
The appearance inspection apparatus according to claim 1, wherein the holding unit supports a lower surface of the holding plate with four tips.   The plurality of positions at which the detection means detects the distance includes a position on the object to be inspected that is closest to two adjacent positions that support the holding plate at the tip of the holding unit, and a position of the holding plate on the holding unit. The visual inspection apparatus according to claim 6, wherein the visual inspection apparatus is set to a position on the object to be inspected that is closest to a midpoint of the other two positions supported by the tip. The appearance inspection apparatus further includes a fixed frame having a mounting surface on which an object to be inspected is formed on its upper surface,
The appearance inspection apparatus according to claim 1, wherein the holding unit is disposed inside the fixed frame. An appearance inspection method for imaging and inspecting an inspection object using an imaging unit,
A holding step for supporting the inspection object with at least three tips and placing the inspection object;
A detection step of detecting a line-of-sight direction distance of the imaging unit from the imaging unit to the inspection object placed on the tip, with respect to a plurality of positions of the inspection object;
Based on each distance detected in the detection step, a control step for moving the tip up and down so that the distance satisfies a predetermined condition;
An autofocus step of capturing an image with the focus of the imaging unit aligned with the inspection object while relatively moving at least one of the inspection object and the imaging unit after the distance satisfies a predetermined condition; Appearance inspection method. The detecting step includes detecting the distance with respect to three positions on the inspection object;
The visual inspection method according to claim 9, wherein the control step includes a step of moving the tip up and down so that the distances to the three positions are equal to each other. The detecting step includes detecting the distance with respect to three or more positions on the inspection object;
10. The control step according to claim 9, wherein the control step includes a step of vertically moving the tip so that the distances to all positions on the inspection object detected in the detection step are within a predetermined range. Appearance inspection method.

Images