JP2007225431A - Visual inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a visual inspection device which images a workpiece without stopping it by moving a conveyance stage and an imaging device synchronously. <P>SOLUTION: The device comprises: the conveyance stage 3 for conveying the inspection workpiece 1 to a prescribed inspection position; a displacement sensor 4 for detecting each height in the optical axis direction of prescribed two points of the workpiece until the work reaches the inspection position; an imaging device 5 whose position in the optical axis direction is held within a focal point depth on the inspection position, having shutter speed of 1/20,000 for imaging the workpiece appearance; an image processing device 8 for processing an image imaged by the imaging device; and a control device 9 for moving the conveyance stage from prescribed one point to the other point of the workpiece, and adjusting the position in the optical axis direction of the imaging device synchronously with movement of the conveyance stage. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an appearance inspection apparatus, for example, an apparatus that performs an appearance inspection by capturing an appearance that is an inspection site such as an electronic substrate and capturing the image with high speed and accuracy.

  A conventional visual inspection apparatus includes a transfer stage that moves a workpiece to be inspected to a predetermined inspection position, and heights in the optical axis direction at two predetermined points in the workpiece until the workpiece reaches the inspection position. That is, a displacement sensor that detects the amount of displacement of the height from the reference plane, an imaging device that captures the appearance of the workpiece in the state where the height position in the optical axis direction is held in the focus range at the inspection position, and imaging The image processing apparatus includes an image processing apparatus that processes an image captured by the device, and a control apparatus that controls the positions of the transfer stage and the imaging device. (For example, refer to Patent Document 1).

JP 2000-266991 A

  The conventional appearance inspection apparatus is configured as described above, and after imaging one point in the work at the inspection position, the image is moved to another point and the next imaging is performed, but the shutter speed of the imaging device is 1 As shown in FIG. 3, the transfer stage for moving the workpiece is stopped at each inspection point as shown in X1 to X5, and the imaging device is kept in the focal range at each position, as shown in FIG. It was necessary to adjust the height position of the imaging device in the optical axis direction as indicated by h1 to h5.

  However, when the speed of the transfer stage for moving the workpiece is increased in order to improve inspection efficiency, the movement time between two predetermined points in the workpiece is shortened. It is necessary to move and stop suddenly.

  However, since the imaging device may use a heavy optical system such as a microscope unit, the time to stop (settling time) becomes long and it becomes difficult to stop at high speed, resulting in high speed. There was a problem that the image could not be acquired.

  In addition, in order to rapidly move and stop a heavy object, it is generally necessary to use a very expensive up / down moving stage.

  The present invention has been made in order to cope with the above-described problems, and provides an appearance inspection apparatus that can move an imaging stage and an imaging device in synchronization with each other and perform imaging without stopping the workpiece. With the goal.

  The visual inspection apparatus according to the present invention includes a transport stage for transporting an inspection work to a predetermined inspection position, and heights in the optical axis direction at predetermined two points of the work before the work reaches the inspection position. A position sensor in the optical axis direction at the inspection position, an imaging device having a shutter speed of 1/20000 or more that images the appearance of the workpiece, and an image captured by the imaging device The image processing apparatus for processing the image and the position of the imaging device in the optical axis direction in synchronization with the movement of the transfer stage, while moving the transfer stage from one predetermined point of the workpiece to another point. And a control device for adjustment.

  The appearance inspection apparatus according to the present invention is configured as described above, uses an imaging device with a high shutter speed, and synchronizes the movement of the conveyance stage and the imaging device in the optical axis direction without stopping the workpiece. The required appearance can be imaged. Therefore, even when an optical system having a large weight is used for the imaging device, the appearance inspection can be performed without any trouble.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the first embodiment, and FIG. 2 is an explanatory diagram showing the relationship between the position of the transfer stage and the vertical position of the imaging device in the first embodiment.

  As shown in FIG. 1, the appearance inspection apparatus according to the first embodiment is configured to drive a workpiece 1 to be inspected in a direction indicated by an arrow by a driving force of a motor 2 and move the workpiece 1 to a predetermined inspection position. Before the workpiece 1 reaches the inspection position, the height in the optical axis direction at two predetermined points (not shown) in the workpiece, that is, the height displacement from the reference plane (not shown) at an appropriate location. The displacement sensor 4 for detecting the position of the workpiece 1 is set in advance so as to be positioned within the depth of focus which is a focal range with respect to the displacement amount in the height direction of the workpiece 1 above the inspection position. An imaging device 5 composed of, for example, a CCD camera with a fixed focal length and a shutter speed of 1/20000 or more, an upper and lower stage 7 that is driven by a motor 6 and adjusts the vertical position of the imaging device 5, and an imaging device 5 Imaged by The motor 2 of the transfer stage 3 and the motor 6 of the upper and lower stages 7 are controlled based on the signal from the image processing apparatus 8 that processes the image and the displacement sensor 4, and the positions of the transfer stage 3 and the imaging device 5 are synchronized. And a control device 9 for adjusting.

  The first embodiment is configured as described above, and the imaging device 5 is configured as a high-speed camera having a shutter speed of 1/20000 or higher so that it can shoot with less light. For example, after imaging at Xa in FIG. 2, when moving to another point, for example, Xb in FIG. 2, the inspection stage X1 to X5 in the middle of FIG. 2 continues to Xb without stopping the transfer stage 3. In the meantime, every time the inspection point X1 to X5 of the work 1 is reached, the depth of focus that is just focused with respect to the height of each inspection point detected in advance by the displacement sensor 4 (indicated by Δ in FIG. 2) The position of the imaging device 5 is adjusted to h1 to h5 in synchronization with the transfer stage 3 so as to correspond to the above, and imaging is performed while moving the workpiece 1 at each position.

  As described above, according to the first embodiment, since the imaging device has a shutter speed of 1/20000 or more, and the transfer stage and the imaging device are moved in synchronization, the workpiece is stopped at each inspection point. As a result, the workpiece can be picked up without any trouble even when a heavy optical system is used for the image pickup device 5, and the appearance can be inspected.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described. Since the basic configuration of the appearance inspection apparatus is the same as that shown in FIG. 1, illustration and description thereof are omitted. The difference from the first embodiment is a method of measuring the movement amount of the transfer stage 3.

  In the first embodiment, the position of the work 1 is estimated by measuring the position of the motor 2. Specifically, the ball screw is rotated by the motor 2 mounted on the transfer stage 3. Thus, the position of the workpiece is read in accordance with the rotational speed of the motor. However, since the screw thread interval of the ball screw is not uniform over the entire length of the ball screw, an error due to this occurs, and the accuracy of the information on the work position and the position of the inspection point is lowered.

For this reason, the second embodiment stops estimating the position of the workpiece based on the motor position, attaches a linear scale or the like to an appropriate fixing portion around the transfer stage 3, and uses the fixed scale as a reference for the position of the workpiece. Is to measure.
Thereby, the accuracy of position information can be improved.

Embodiment 3 FIG.
Next, a third embodiment of the present invention will be described. Since the basic configuration of the appearance inspection apparatus is the same as that shown in FIG. 1, illustration and description thereof are omitted. The difference from the first embodiment is that a line sensor is used as the imaging device 5.

  Unlike the CCD camera according to the first embodiment, the line sensor has a large number of pixels arranged in the lateral direction. By arranging this arrangement direction in a direction perpendicular to the workpiece conveyance direction, The field of view in the perpendicular direction can be enlarged, and a wide range of inspections can be performed.

It is a block diagram which shows the structure of Embodiment 1-3 of this invention. 6 is an explanatory diagram for explaining a positional relationship between a transfer stage and an imaging device in Embodiment 1. FIG. It is explanatory drawing for demonstrating the positional relationship of the conveyance stage and imaging device in a conventional apparatus.

Explanation of symbols

1 work, 2 motor, 3 transport stage, 4 displacement sensor,
5 imaging device, 6 motor, 7 upper and lower stage, 8 image processing device,
9 Control device.

Claims (3)

  A transport stage for transporting a workpiece for inspection to a predetermined inspection position, a displacement sensor for detecting the height in the optical axis direction at two predetermined points of the workpiece until the workpiece reaches the inspection position, and the inspection An image pickup device in which the position in the optical axis direction is held within the depth of focus at the position, the shutter speed is 1/20000 or more for picking up the appearance of the workpiece, the image processing device for processing the image picked up by the image pickup device, and the above An external appearance including a control device that moves the transfer stage from a predetermined point of the workpiece toward another point and adjusts the position of the imaging device in the optical axis direction in synchronization with the movement of the transfer stage. Inspection device.   2. The appearance inspection apparatus according to claim 1, wherein the position of the workpiece is confirmed by a linear scale attached to a fixed portion.   The appearance inspection apparatus according to claim 1, wherein the imaging device is a line sensor.

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