JP2011013009A - Visual inspection method and visual inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To speedily and surely focus on an inspected object placed on a tray.SOLUTION: The visual inspection method uses a device including a stage on which a tray placing the inspected object is disposed, a back/front and a left/right drive mechanisms which horizontally drive the stage, an imaging part which images the inspected object placed on the tray, and an up/down drive mechanism which vertically drives the imaging part. The methods performs at least a first step of controlling the back/front and the left/right drive mechanisms to move the stage, a second step of determining whether a vertical position of the imaging part corresponding to a horizontal position of the stage is previously memorized, a third step of moving the imaging part to the vertical position when the vertical position is memorized or memorizing the horizontal position of the stage in relation to the vertical position of the imaging part after the vertical position of the imaging part is adjusted when the vertical position is not memorized, and a fourth step of imaging the inspected object using the imaging part.

Description

  The present invention relates to an appearance inspection method and an appearance inspection apparatus, and more particularly, to an appearance inspection method and an appearance inspection apparatus for photographing an inspection object in a state of being stored in a tray and performing inspection based on the photographed image.

  In an appearance inspection in which an inspection object is photographed by a photographing unit such as a camera, and the photographed image is used to determine whether the inspection object is a non-defective product, the position of the inspection object is always constant with respect to the photographing unit. In this case, the imaging unit is previously fixed at a position where the inspection object is in focus and the inspection object is imaged.

  With regard to such an appearance inspection, for example, Japanese Patent Application Laid-Open Publication No. 2004-228561 discloses an imaging unit that images an inspection object in an imaging field, a moving unit that moves the imaging field, and a feature area storage that stores a feature area of the inspection object. Posture detecting means for searching for a characteristic region of the inspection object from an image photographed in the field of view by the photographing means, calculating posture information of the inspection object with reference to information obtained by the search, and posture information A visual inspection apparatus comprising a movement control means for determining a photographing position of a photographing field of view by a moving means person and controlling the moving means is disclosed.

JP 2004-093339 A

  In the technique of the above-mentioned patent document 1, when the inspection object is stored in the pocket of the tray, the tray may be deformed. Therefore, when the position of the inspection object is fixed, the inspection object that is out of focus is generated. To do. In such a case, it is necessary to control the position of the imaging unit in accordance with the change in the position of the inspection object due to the deformation of the tray and to adjust the focus.

  As a general measure, there is a method of measuring the distance between the imaging unit and the inspection object using a distance measuring sensor or a displacement sensor and controlling the position of the imaging unit according to the result. However, a sensor capable of high-precision distance measurement required for focusing requires that the sensor be attached to a position closer to the inspection object than the imaging unit, and that the sensor is closer to the inspection object stored in the tray. However, there is a problem that the sensor becomes an obstacle to photographing because the size is often larger. In addition, a high-precision sensor is expensive, and there is a problem that the cost is increased by attaching the sensor to each photographing unit.

  As another countermeasure, a method of measuring the tray shape before inspection can be considered. However, this method requires a long time to measure the tray shape, and thus there is a problem that the time for the entire appearance inspection becomes long.

  The present invention has been made in view of the above problems, and its main purpose is to provide an appearance inspection method and an appearance inspection apparatus capable of quickly and reliably focusing on an inspection object stored in a tray. It is to provide.

  In order to achieve the above object, the present invention provides a stage on which a tray storing an inspection object is placed, a front-rear drive mechanism and a left-right drive mechanism for driving the stage in a horizontal direction, and the inspection stored in the tray. An appearance inspection method using an apparatus including at least an imaging unit that images an object and a vertical drive mechanism that drives the imaging unit in a vertical direction, and controls the front-rear drive mechanism and the left-right drive mechanism. A first step of moving the stage to a position where the imaging unit can image the inspection object; and a second step of determining whether a vertical position of the imaging unit corresponding to a horizontal position of the stage is stored in advance. And when the vertical position is stored, the vertical drive mechanism is controlled to move the photographing unit to the vertical position, and when the vertical position is not stored A third step of storing the horizontal position of the stage and the vertical position of the imaging unit in association with each other after the vertical position of the imaging unit is adjusted; and a step of imaging the inspection object using the imaging unit. At least four steps are executed.

  According to the appearance inspection method and the appearance inspection apparatus of the present invention, paying attention to the tendency of the tray deformation to be similar in the case of the same type of tray, the inspection position (the horizontal position of the stage, that is, the front-rear drive mechanism and The position of the left and right drive mechanism) and the focus position (the vertical position of the photographing unit, that is, the position of the vertical drive mechanism) are stored in association with the tray type as necessary, and the photographing position is referred to by referring to the stored information. By determining, the focus can be adjusted in a short time.

  Also, even when the tendency of tray deformation changes or the type of tray changes, the focus is adjusted again, and the inspection position, the focus position, and the tray type are stored in association with each other as necessary. Can be continued.

  In addition, by confirming the focus on the image used for inspection, it is not necessary to take an image for focusing, and focusing can be performed without increasing the inspection time. Measurement equipment is not required, and focusing is possible with an inexpensive configuration.

It is a figure which shows typically the structure of the external appearance inspection apparatus which concerns on one Example of this invention. It is a perspective view which shows an example of the tray shape of the external appearance inspection apparatus which concerns on one Example of this invention. It is a flowchart figure which shows the external appearance inspection procedure of the test target object using the external appearance inspection apparatus which concerns on one Example of this invention. It is a flowchart figure which shows the procedure in the case of performing a visual inspection continuously using the visual inspection apparatus which concerns on one Example of this invention. It is a flowchart figure which shows the other example of the external appearance inspection procedure of the test target object using the external appearance inspection apparatus which concerns on one Example of this invention. It is a flowchart figure which shows the other example of the external appearance inspection procedure of the test target object using the external appearance inspection apparatus which concerns on one Example of this invention.

  As shown in the background art, it is important to focus on the inspection object in the appearance inspection in which the inspection object is photographed and inspected, but the inspection object is stored in the tray pocket Is out of focus due to deformation of the tray.

  To solve this problem, a method of measuring the distance to the inspection object using a distance measuring sensor or a displacement sensor is conceivable. However, a sensor capable of measuring a distance with high accuracy is large and close to the inspection object. Since it is attached, there is a problem that the imaging of the inspection object is hindered, and there is a problem that the cost increases because a high-precision sensor is expensive. Although a method of measuring the tray shape before the inspection is conceivable, this method has a problem that it takes time to measure the tray shape and the time for the entire appearance inspection becomes long.

  Therefore, in the present invention, attention is paid to the fact that the tray deformation tendency is similar in the case of the same type of tray, and when the focus adjustment is completed, the inspection position (the horizontal position of the stage, that is, the front and rear drive mechanism and the left and right drive mechanism). Position) and focus position (vertical position of the imaging unit, that is, the position of the vertical drive mechanism) and the type of tray as necessary are stored in association with each other, and the imaging unit is stored when performing inspection at the same inspection position The inspection is performed by moving to the focused position. Further, when the tendency of tray deformation changes or when the tray type changes, the focus is adjusted again, and the inspection position, the focus position, and the tray type are stored in association with each other as necessary. Allow inspection to continue. In addition, focusing is performed using an image taken at the time of inspection, thereby eliminating the time for capturing an image for focusing, enabling rapid inspection, and for distance measurement such as a distance sensor or a displacement sensor. It eliminates the need for equipment and enables focusing with an inexpensive configuration.

  In order to describe the above-described embodiment of the present invention in more detail, an electronic component visual inspection method and visual inspection apparatus according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram schematically illustrating a configuration of an appearance inspection apparatus according to the present embodiment, and FIG. 2 is a perspective view illustrating an example of a tray shape. 3 to 6 are flowcharts showing an appearance inspection procedure using the appearance inspection apparatus of the present embodiment.

  As shown in FIG. 1, the appearance inspection apparatus according to the present embodiment includes a photographing unit 3 such as a CCD (Charge Coupled Devices) camera that photographs a test object 1 such as an IC chip stored in a tray 2, and a tray 2. , The front / rear drive mechanism 5 and the left / right drive mechanism 6 for controlling the position in the surface direction of the stage 4 (referred to as a horizontal position), and the position of the photographing unit 3 substantially orthogonal to the surface direction of the stage 4. A vertical drive mechanism 7 for controlling (vertical position), a control unit 8 and the like. The front / rear drive mechanism 5, the left / right drive mechanism 6 and the vertical drive mechanism 7 are controlled by instructions from the control unit 8, The imaging unit 3 is controlled to image the inspection object 1.

  The stage 4 is provided with a positioning mechanism 9 for fixing the position of the tray 2. The control unit 8 includes a calculation unit such as a CPU (Central Processing Unit) and a storage unit such as a ROM (Read Only Memory), a RAM (Random Access Memory), and an HDD (Hard Disk Drive). Reads the current positions of the stage 4 and the imaging unit 3 from the front-rear drive mechanism 5, the left-right drive mechanism 6, and the vertical drive mechanism 7, and also reads an image obtained by imaging the inspection object 1 from the imaging unit 3, and associates these pieces of information. Is stored in the storage unit.

  The operation of the appearance inspection apparatus having the above configuration will be described below.

  Prior to the start of inspection, the tray 2 is placed on the stage 4 and the position of the tray 2 is fixed by the positioning mechanism 9. As the shape of the tray 2, a shape in which the tray pocket 21 is provided on the upper surface of the tray 2 as shown in FIG. 2 can be considered. In this case, the inspection object 1 is stored in the tray pocket 21. In addition, when a plurality of types of trays 2 are used, the type of the tray 2 is specified in advance.

  In such a state, the procedure for performing an appearance inspection on one inspection object 1 will be described with reference to the flowchart of FIG.

  When the inspection is started, first, the control unit 8 determines an imaging position (inspection position and focus position). The inspection position (the horizontal position of the stage 4, that is, the positions of the front-rear drive mechanism 5 and the left-right drive mechanism 6) is determined by the position of the inspection object 1 to be inspected. On the other hand, the focus position (the vertical position of the photographing unit 3, that is, the position of the vertical drive mechanism 7) is determined from previously stored information.

  Specifically, in the storage unit such as the memory or the HDD, the positions of the front and rear drive mechanism 5 and the left and right drive mechanism 6 when the inspection has been performed so far, and the position of the vertical drive mechanism 7 at that time, Are stored in association with each other, and the control unit 8 includes the up-and-down drive mechanism 7 corresponding to the positions of the front-rear drive mechanism 5 and the left-right drive mechanism 6 when imaging the inspection object 1 to be inspected. It is confirmed whether or not the position is stored (S101).

  In addition, when there is only one type of tray 2 for storing the inspection object 1, since the tendency of deformation of the tray is similar, the same focus position can be used at the same inspection position. In the case of multiple types, the tendency of tray deformation may be different. In such a case, the position of the front / rear drive mechanism 5 and the left / right drive mechanism 6, the position of the vertical drive mechanism 7 and the type of the tray 2 (the control unit 8 may automatically detect or not shown in the storage unit). And may be input by operating the operation unit), and corresponding to the positions of the front-rear drive mechanism 5 and the left-right drive mechanism 6 when inspected using the same type of tray 2. It is also possible to check whether the position of the vertical drive mechanism 7 is stored.

  When the position of the vertical drive mechanism 7 is stored, the control unit 8 reads the stored position of the vertical drive mechanism 7 as a photographing position (S102), and the front / rear drive mechanism 5 and the left / right drive mechanism 6 are read out. The vertical drive mechanism 7 is controlled to move the stage 4 and the photographing unit 3 to the photographing position (S103).

  On the other hand, when the position of the vertical drive mechanism 7 is not stored, the control unit 8 moves the photographing unit 3 and searches for a position where the focus is achieved. Specifically, the control unit 8 controls the front / rear drive position 5 and the left / right drive mechanism 6 to move the stage 4 to the photographing position (S104), and in that state, moves the photographing unit 3 by the vertical drive mechanism 7. The focus is adjusted (S105). When the focus position is determined, the control unit 8 reads the position of the vertical drive mechanism 7 and stores the position in association with the position of the front / rear drive mechanism 5 and the left / right drive mechanism 6 at that time and the type of the tray 2 as necessary. (S106). In addition, as a method for determining the in-focus position, a method in which the position of the vertical drive mechanism 7 is manually moved and visually confirmed can be considered.

  When the above processing is completed, the control unit 8 causes the imaging unit 3 to image the inspection object 1 (S107) and confirms whether or not the object is in focus (S108). As a method for confirming whether or not the image is in focus, there are a method of differentiating the entire image and judging using the maximum value, a method of judging using a value obtained by performing differentiation twice. However, it is not limited to these methods.

  If the image is in focus, an inspection is performed using the image captured by the imaging unit 3 (S109), and the process for one inspection object 1 is terminated.

  On the other hand, when the focus is not achieved, the control unit 8 moves the photographing unit 3 to determine the focus position, similarly to the case where the position of the vertical drive mechanism 7 described above is not stored ( In step S105, the position of the vertical drive mechanism 7 is read out and stored in the storage unit (S106). When the storage is completed, the inspection object 1 is imaged again (S107), and it is confirmed whether or not it is in focus (S108).

  The above flow is an inspection for one inspection object 1, but when an inspection is performed on a plurality of inspection objects 1, it is possible to repeat the above-described procedure. In this case, it can be considered that the confirmation and inspection of whether or not the focus is achieved after the image of the inspection object 1 is taken and the operation of moving to the position of the inspection object 1 to be inspected next are performed in parallel. Thereby, since confirmation of focus can be performed during the operation of moving to the position of the inspection object 1 to be inspected next, processing can be performed without increasing the inspection time.

  Next, a procedure for performing an appearance inspection on a plurality of trays 2 will be described with reference to a flowchart of FIG.

  When the new tray 2 is supplied (Yes in S201), the imaging position of the inspection object 1 to be inspected first is set (S202), and the appearance inspection of the inspection object 1 is performed according to the flowchart of FIG. 3 described above (S203). When the inspection is completed, the next photographing position is set (205). This process is performed for all the inspection objects 1 stored in the tray 2.

  When the inspection is completed for all the inspection objects 1 stored in the tray 2 (Yes in S204), a new tray 2 is supplied and the same processing is performed. When the deformation of the new tray 2 is different from that of the previous tray or when a different type of tray 2 is used, the process is continued with the focus again during the appearance inspection.

  Thus, in the appearance inspection, it is confirmed whether or not the focus position (position of the vertical drive mechanism 7) corresponding to the inspection position (position of the front-rear drive mechanism 5 and the left-right drive mechanism 6) is stored. In this case, the photographing unit 3 is adjusted to the focus position, and if not stored, after the focus is adjusted, the position of the vertical drive mechanism 7 is associated with the positions of the front-rear drive mechanism 5 and the left-right drive mechanism 6. Since it memorize | stores, the focus adjustment in the case of test | inspecting the test target object 1 accommodated in the same position can be performed rapidly. In addition, by checking whether the image is in focus using the image taken at the time of the inspection, it is possible to perform a quick inspection without taking the time to capture the image for focusing, and the distance from the distance measuring sensor, the displacement sensor, etc. Focusing can be performed with an inexpensive configuration, eliminating the need for measuring equipment.

  Even if the focus position is adjusted automatically, the appearance inspection is performed after confirming that the focus is in focus, so if the tendency of tray deformation changes, the inspection will be performed with the focus out of alignment. Can be prevented in advance.

  Further, by storing the position of the vertical drive mechanism 7 in association with the position of the front / rear drive mechanism 5 and the left / right drive mechanism 6 and the type of the tray 2, the focus position is automatically set only when the same type of tray 2 is used. Therefore, when the type of the tray 2 is changed, it is possible to prevent the inspection from being performed with the focus out of focus.

  In addition, this invention is not limited to the said Example, The structure and control method can be changed suitably, unless it deviates from the meaning of this invention. For example, in the above flow, the focus position is measured in the inspection flow, but it is also possible to measure the focus position in advance before starting the inspection and store the position information in the control unit 8.

  In the above flow, when the position of the vertical drive mechanism 7 corresponding to the position of the front / rear drive mechanism 5 and the left / right drive mechanism 6 is not stored, focusing is performed, but the position information is intermittently stored. Thus, it is also possible to approximate the position information of the unstored part by a calculation formula.

  Further, in the above flow, it is confirmed whether or not the object is in focus every time the inspection object 1 is photographed. However, when the inspection object 1 is larger than the field of view of the photographing unit 3, the inspection object 1 is inspected. When the subject 1 is imaged while being divided into a plurality of fields of view, as shown in the flowchart of FIG. 5, the position of the vertical drive mechanism 7 when it is determined that the focus is in the first field of view is set to the remaining fields. It is also possible to apply to the field of view. At this time, as shown in the flowchart of FIG. 6, the position of the vertical drive mechanism 7 is stored only in the first field of view, and if it is not the first field of view, the vertical drive mechanism 7 of the first field of view already stored is stored. It is also possible to read the position.

  In addition, it is possible to set a reference position for each of the front / rear drive mechanism 5, the left / right drive mechanism 6, and the vertical drive mechanism 7, and set the stored information as the distance from the reference position. Further, the information to be stored may be the position of the tray pocket 21 instead of the positions of the front-rear drive mechanism 5 and the left-right drive mechanism 6. In this case, the position of the tray pocket 21 can be stored such as what number from the right end and what number from the upper end.

  Further, the front-rear drive mechanism 5 and the left-right drive mechanism 6 can be attached to the photographing unit 3. Similarly, the vertical drive mechanism 7 can be attached to the stage 4.

  INDUSTRIAL APPLICABILITY The present invention can be used for a method and an apparatus for visual inspection of electronic components such as semiconductors, in particular, visual inspection of electronic components such as semiconductors that are stored in a tray.

DESCRIPTION OF SYMBOLS 1 Inspection object 2 Tray 3 Image pick-up part 4 Stage 5 Front-rear drive mechanism 6 Left-right drive mechanism 7 Vertical drive mechanism 8 Control part 9 Positioning mechanism 21 Tray pocket

Claims (8)

A stage on which a tray storing an inspection object is placed, a first drive mechanism and a second drive mechanism for driving the stage in a horizontal direction, and an imaging unit for photographing the inspection object stored in the tray; A third drive mechanism for driving the imaging unit in a vertical direction, and an appearance inspection method using an apparatus including at least
A first step of controlling the first drive mechanism and the second drive mechanism to move the stage to a position where the imaging unit can image the inspection object;
A second step of determining whether a vertical position of the photographing unit corresponding to a horizontal position of the stage is stored in advance;
When the vertical position is stored, the third driving mechanism is controlled to move the photographing unit to the vertical position. When the vertical position is not stored, the vertical position of the photographing unit is adjusted. A third step of storing the horizontal position of the stage and the vertical position of the photographing unit in association with each other;
A visual inspection method characterized by performing at least a fourth step of photographing the inspection object using the photographing unit. Further executing a fifth step of determining whether the photographing unit is in focus based on an image obtained by photographing the inspection object;
2. The appearance inspection method according to claim 1, wherein if it is determined that the image is out of focus, the process returns to the third step, and the process when the vertical position is not stored is executed.   The appearance inspection method according to claim 2, wherein an image obtained by photographing the inspection object in the fifth step is the same as an image used for an appearance inspection. In the second step, it is determined whether the horizontal position of the stage and the vertical position of the photographing unit corresponding to the type of the tray are stored,
In the third step, if the vertical position is not stored, the vertical position of the photographing unit is adjusted, and then the horizontal position of the stage and the tray type are associated with the vertical position of the photographing unit. The visual inspection method according to claim 1, wherein the visual inspection method is stored. A stage on which a tray storing an inspection object is placed, a first drive mechanism and a second drive mechanism for driving the stage in a horizontal direction, and an imaging unit for photographing the inspection object stored in the tray; A third drive mechanism for driving the imaging unit in the vertical direction; and a control unit,
The controller determines whether a vertical position of the imaging unit corresponding to a horizontal position of the stage is stored in advance after the imaging unit moves the stage to a position where the inspection object can be imaged. When the vertical position is stored, the third drive mechanism is controlled to move the photographing unit to the vertical position. When the vertical position is not stored, the vertical position of the photographing unit is After being adjusted, the horizontal position of the stage and the vertical position of the imaging unit are stored in association with each other, and thereafter, control for causing the imaging unit to image the inspection object is performed. .   The controller determines whether the imaging unit is in focus based on an image obtained by imaging the inspection object, and determines that the vertical position is not stored when it is determined that the image is not in focus. The appearance inspection apparatus according to claim 5, wherein control is performed.   The said control part uses the same image by judgment whether the imaging | photography part image | photographed the said test target object is in focus, and an external appearance test | inspection. Appearance inspection apparatus as described.   The control unit determines whether the horizontal position of the stage and the vertical position of the photographing unit corresponding to the type of the tray are stored, and when the vertical position is not stored, the vertical position of the photographing unit The visual inspection according to any one of claims 5 to 7, wherein the horizontal position of the stage, the type of the tray, and the vertical position of the photographing unit are stored in association with each other after the adjustment is made. apparatus.

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