JP2006162250A - Pattern inspection device for film workpiece - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for acquiring a pattern image without any blur by causing an imaging unit to scan along a flexure so as to keep a focus position from being displaced even if the flexure is widthwise developed in a film workpiece, as to a pattern inspection device for a film workpiece wherein the long film workpiece is widthwise scanned by the imaging unit to acquire the pattern image formed on the film workpiece for inspection. <P>SOLUTION: A distance sensor is provided in the vicinity of the imaging unit for measuring a distance to a surface of the workpiece. When the imaging unit is moved widthwise across the workpiece while scanning, the imaging unit is moved so that the distance to the workpiece coincides with a focal distance based on distance information from the distance sensor. It is also possible to move the film workpiece. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a film work inspection apparatus that automatically inspects a pattern formed on a long film work such as a TAB tape or an FPC (flexible printed circuit board).
In particular, the present invention relates to a film work inspection apparatus that automatically picks up an image while performing autofocus (autofocus) when the film work is slackened (curved) in the width direction.

In order to automatically inspect the appearance of patterns on circuits such as TAB tapes and FPCs (flexible printed circuit boards) that are formed on a long film work (hereinafter also referred to as a work), the pattern image is automatically converted into a CCD. There is known a pattern inspection apparatus that determines pass / fail by comparing with a master pattern acquired in advance by an image sensor such as the above.
In Patent Document 1, in the inspection apparatus for a film work as described above, a CCD line sensor for acquiring image data is arranged in the longitudinal direction of the film work in response to the widening of the film work. An apparatus for capturing images by scanning in the direction is shown.

However, the film work as described above is warped in the width direction due to processing in processes such as exposure development and etching for forming a pattern, and further, sagging due to its own weight is added. It has a shape.
When such a curved film work is inspected by using the apparatus described above, the surface of the work is displaced from the focal position of the image sensor during scanning only by scanning the image sensor in the width direction of the work. The acquired pattern image is blurred and cannot be inspected.

If the back surface of the film work is adsorbed by a flat stage, the curved surface shape of the work is corrected, and the above problem can be solved. However, if a stage is used, illumination light is irradiated from the back side of the workpiece, and it becomes difficult to inspect with transmitted illumination light that acquires a pattern image by the light transmitted through the workpiece, and scratches may occur on the back side of the workpiece In some cases, it may be necessary to inspect without using a stage.
Therefore, as in Patent Document 2 and Patent Document 3, the edge of the film work in the width direction is mechanically held, the tension is applied to correct the curvature of the work, and the film work is held on a flat surface. It has been proposed to hold at the focal position.

  However, film works such as TAB tape and FPC are becoming wider and thinner year by year. When the width is widened and thinned, the film work cannot be completely bent by merely holding the edge of the work and applying tension, and may not be held at the focal position of the image sensor.

In Patent Document 4, when a film work having a curved surface shape in the width direction as described above is inspected, a line sensor that is an image sensor is scanned twice in the width direction of the film work at the same position. Shown to get.
That is, the distance from the film work to the line sensor is continuously obtained based on the detection signal of the line sensor acquired in the first driving scan, and the distance data obtained in the first time is also obtained in the second driving scan. At the same time, the line sensor is driven and scanned along the curvature of the film work to obtain a pattern image without blur.

However, if the line sensor is scanned twice for one inspection, the inspection processing time becomes long and the throughput decreases.
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a film work pattern inspection apparatus that acquires an image of a pattern by scanning the image sensor in the width direction of a long film work. It is an object of the present invention to provide an apparatus capable of acquiring a pattern image without blurring by only one scanning.

JP 2001-160571 A JP 2004-28597 A JP 2002-217249 A JP 2002-372503 A

In the present invention, the above problems are solved as follows.
In a film work pattern inspection apparatus that scans an image pickup unit in the width direction of a long film work and acquires and inspects an image of a pattern formed on the film work, the image pickup unit or the film work is attached to the image pickup unit. An optical axis direction moving mechanism for moving in the optical axis direction is provided.
In addition, a distance sensor that measures the distance to the film work is provided in the vicinity of the imaging unit, and moves in the width direction of the film work together with the imaging unit while measuring the distance to the film work.

The apparatus control unit moves the imaging unit or the film work in the optical axis direction of the imaging unit by the optical axis direction moving mechanism based on the distance information to the film work measured by the distance sensor, Keep in focus position.
The position where the distance sensor is provided may be a position on the extension of the longitudinal direction of the CCD line sensor arranged along the longitudinal direction of the film work as an image sensor, or a direction perpendicular to the longitudinal direction of the CCD line sensor. Thus, the forward direction in which the imaging unit is scanned may be used.

In the present invention, when the imaging unit moves in the width direction of the film work and acquires a pattern image, the imaging unit or the film work moves in the optical axis direction of the imaging unit based on the distance information from the distance sensor. Since the curved film work is kept at the focal position, an image without blur can be obtained by one scan.
Further, by providing the distance sensor in a direction orthogonal to the longitudinal direction of the CCD line sensor that is the image sensor and in the forward direction in which the image pickup unit is scanned, the distance to the portion where the CCD line sensor acquires an image is provided. Therefore, it is possible to obtain a pattern image with high accuracy and without blurring.

FIG. 1 is a diagram showing a schematic configuration of a film work pattern inspection apparatus according to an embodiment of the present invention.
The film work pattern inspection apparatus (hereinafter also referred to as a pattern inspection apparatus) according to the present embodiment includes a film work transport mechanism 10 and a film work W (hereinafter also referred to as a work) such as a TAB tape or FPC on which a pattern is formed. Then, the tape is unwound from the delivery reel 11 of the tape transport mechanism 10 and taken up by the take-up reel 12.

In the vicinity of the take-up reel 12, a marker portion 3 for marking a defective pattern is provided. In the marker part 3, a pattern determined to be defective is marked with punching, coloring, or the like so that it can be visually confirmed that the part is defective.
The film work W delivered from the delivery reel 11 is sent to the inspection unit 5. A conveyance roller 71 is provided on the conveyance downstream side of the inspection unit 5, and a brake roller 72 is provided on the conveyance upstream side of the inspection unit 5, and the film work W is intermittently applied while being tensioned in the longitudinal direction. It is conveyed to.

The inspection unit 5 is provided with a reflective illumination unit 21 and an imaging unit 51 that captures a pattern of a circuit or the like formed on the workpiece W by illumination light reflected by the film workpiece W.
The illumination means may be provided on the opposite side of the imaging unit 51 with respect to the film work W, and may be the transmission illumination means 22 (indicated by a dotted line in the figure). In this case, the imaging unit 51 captures a pattern of a circuit or the like formed on the workpiece W with illumination light transmitted through the film workpiece W.

A scanning unit 80 is attached to the imaging unit 51, and the scanning unit places the imaging unit 51 and the reflected illumination unit 21 on the inspection pattern of the film workpiece W in the width direction of the workpiece W (front and rear direction in the figure). An image of the entire inspection area (area where the pattern is formed) of the film work W is obtained.
The structure of the scanning unit 80 and the detailed operation when the imaging unit 51 acquires an image will be described later.
Further, when the pattern image is acquired by the imaging unit 51, the inspection unit 5 holds both ends (edges) of the film work W in the width direction, pulls the work W in the width direction, applies tension, and loosens. A work edge holding mechanism 90 for reduction is also provided.

The control unit 4 of the apparatus performs image processing on the image pattern picked up by the image pickup unit 51 and compares it with a master pattern that is stored in advance as a reference for inspection to determine whether the product is good or bad. The operation of the entire pattern inspection apparatus such as the inspection unit 5, the marker unit 3, and the tape transport mechanism 10 is controlled.
FIG. 2 is a diagram showing a detailed configuration of the inspection unit of the pattern inspection apparatus of FIG. 1, and a first embodiment of the present invention will be described with reference to FIG. The reflected illumination means 21 and the work holding mechanism 90 are not shown.

2A is a plan view of the inspection unit viewed from a direction orthogonal to the surface on which the film work is conveyed, FIG. 2B is a diagram viewed from the direction of conveyance of the film work, and FIG. It is the figure seen from the width direction of the film work.
Reference numeral 51 denotes an imaging unit. The imaging unit 51 includes a CCD line sensor 52 that is an imaging element, and an optical element (single or multiple lenses) that forms an image of a pattern on the film work W on the CCD line sensor 52. The lens unit 53 is configured.

As shown in FIG. 2A, the CCD line sensor 52 is provided such that its longitudinal direction is parallel to the longitudinal direction of the film work W, that is, parallel to the transport direction of the film work W.
Also, as shown in FIGS. 2B and 2C, the imaging unit 51 captures an image in the width direction (X direction) of the film work W so that the positional relationship between the CCD line sensor 52 and the lens unit 53 does not change. The unit 51 is configured to move independently in the optical axis L direction (Z direction).
The optical axis L of the imaging unit 51 is a virtual straight line connecting the center of the CCD line sensor 32 provided in the imaging unit 51 and the center of the optical element arranged in the lens unit 53. Orthogonal to the plane.

The imaging unit 51 is attached to the imaging unit holding base 54 via a telescopic shaft 58 and is moved in the optical axis L direction (Z direction) by an optical axis direction moving motor 57 provided on the imaging unit holding base 54. To do. Thereby, the imaging unit 51 approaches or separates from the film work W.
Further, the imaging unit holding base 54 is moved along the rail 56 by the scanning movement motor 55.
The rail 56 is provided so as to extend in a direction orthogonal to the conveyance direction of the film work W. Therefore, the imaging unit 51 moves in the width direction of the film work W when the imaging unit holding base 54 moves along the rail 56. Scan and move in (X direction).

A distance sensor 59 is attached to the lens unit 53 of the imaging unit 51 to measure the distance to the surface of the film work W, and the measured distance data to the film work W is sent to the control unit 4 of the apparatus. It is done.
The distance sensor 59 uses a commercially available length measuring device that measures the distance by reflecting red light having a wavelength of 700 nm to an object.
The reason why a light sensor that outputs light of this wavelength is used as a distance sensor is that polyimide is often used as a material for resin used in TAB tape and FPC, and polyimide reflects red light having a long wavelength efficiently. Because.

In the first embodiment, the distance sensor 59 is attached to the lens unit 53 of the image pickup unit 51 at a position on the longitudinal extension of the CCD line sensor 52.
Therefore, the position where the distance sensor 59 measures the distance to the film work W is a position on the extension of the film work W in the longitudinal direction with respect to the position imaged by the CCD line sensor 52.
The distance sensor 59 moves together with the imaging unit 51 when the imaging unit 51 moves in the workpiece width direction (X direction) and the optical axis L direction (Z direction).

FIG. 3 is a diagram for explaining the operation of the image pickup unit in the first embodiment, and is a view of the image pickup unit as seen from the transport direction of the film work, as in FIG.
The operation for controlling the imaging unit to the focal length with respect to the film work at the time of pattern imaging will be described below with reference to FIG.
Prior to the pattern inspection of the film work W, as a preparation, the relationship between the focal position of the imaging unit 51 and the distance to the surface of the film work W by the distance sensor 59 is obtained as follows.

A flat plate on which a test pattern is formed is placed in the optical axis L direction of the imaging unit 51, the test pattern is focused on, and the test pattern is imaged on the CCD line sensor 52.
At that time, the distance to the surface of the film work W is measured by the distance sensor 59 and this is set as the focal length F, and the focal length F is stored in the control unit 4 of the apparatus.
In this case, the measured distance is a distance from the distance sensor 59 to the surface of the workpiece W, and in an optically strict sense, it is different from the focal length of the optical element of the lens unit 53 of the imaging unit 51, but the present invention. , The distance from the distance sensor 59 to the surface of the workpiece W measured by the distance sensor 59 at the position where the pattern is formed on the CCD line sensor 52 of the imaging unit 51 is defined as the focal length.
Apart from this, a master pattern serving as a reference for inspection is also stored in the control unit.

After the above preparation is completed, the pattern inspection is started. A film work W to be inspected is wound around a delivery reel and set in the pattern inspection apparatus shown in FIG.
As described above, the film work W is conveyed, and the portion to be inspected stops at the inspection portion 5 of the apparatus.

As shown in FIG. 3 (a), the distance sensor 59 measures the distance to the surface of the film work W with respect to the film work W conveyed to the inspection section 5, and the data of the measured distance A is obtained from the apparatus. Send to control unit 4.
The control unit 4 compares the measured distance A with the focal length F stored above, calculates the difference A−F, and moves the imaging unit 51 in the optical axis L direction by the distance A−F. The optical axis direction moving motor 57 is driven so as to be lowered.

Thereby, as shown in FIG.3 (b), the imaging unit 51 falls in the direction (Z direction) which approaches the film work W along the optical axis L direction by the distance AF.
Since the distance sensor 59 is attached to the lens unit 53 of the imaging unit 51, the distance sensor 59 is lowered along with the imaging unit 51 by a distance A-F.
The distance sensor 59 repeats the measurement of the distance to the film work W at a specific short cycle and continues to send the distance data to the control unit 4.
The control unit 4 lowers the imaging unit 51 until the distance A-F becomes zero.

When the imaging unit 51 reaches the focal length F, the difference between the measurement distance data A and the focal length F disappears, so the control unit 4 stops driving the optical axis direction moving motor 57 and the imaging unit 51 is maintained at the focal length F. Is done.
A pattern formed on the film work W is imaged on the CCD line sensor 52. The CCD line sensor 52 acquires the formed pattern image and sends it to the control unit 4, and the control unit 4 performs image processing and stores it.

Subsequently, the scanning movement motor 55 is driven, and the imaging unit 51 and the distance sensor 59 are scanned in the width direction (X direction) of the film work W together with the imaging unit holding base 54.
The imaging unit 51 acquires a pattern image of the film work W by the CCD line sensor 52 while being scanned, and the distance sensor 59 measures the distance to the film work W.

If the film work W sag in a curved shape with respect to the width direction, the distance A to the film work W measured by the distance sensor 59 again as shown in FIG. 3A as the imaging unit 51 is scanned. Becomes longer.
The control unit compares the measured distance A and the focal length F, calculates the difference A−F, and again, as shown in FIG. 3B, the imaging unit 51 moves the optical axis by the difference A−F. The optical axis direction moving motor 57 is driven so as to descend in the L direction (Z direction), and the position of the imaging unit 51 is kept at the focal length F.

As a result, the CCD line sensor 32 can always obtain a pattern image with no blur.
The slack of the film work W is considered to be most slack in the vicinity of the center with respect to the work width direction. Therefore, when the scanning of the image pickup unit 51 passes the center of the work width direction, this time is measured by the distance sensor 59. The distance A to the film work W becomes shorter.

In that case, the control unit 4 raises the imaging unit 51 in the optical axis L direction (Z direction) by the measured distance A and the focal length F difference A−F, and the position of the imaging unit 51 is set to the focal length F. keep.
In this way, the imaging unit 51 scans the inspection area in the width direction of the film work W, the CCD line sensor 32 acquires image data free from pattern blur, and the data is sent to the control unit 4. .

After the scanning movement of the imaging unit 51 is completed, the control unit 4 performs image processing on the transmitted image data, and compares the stored master pattern with the stored master pattern to determine pass / fail.
In the present embodiment, the position where the distance is measured by the distance sensor 59 and the position where the CCD line sensor 32 acquires an image are different with respect to the longitudinal direction of the film work W.

However, the distance sensor 59 is attached to the lens unit 53 of the image pickup unit 51, and corresponds to a position directly next to the longitudinal direction of the CCD line sensor 32, and the amount of curvature of the film work W is relative to the longitudinal direction of the work. Is not much different.
Therefore, even if the distance of the imaging unit 51 is adjusted based on the distance to the workpiece W measured at this position, the CCD line sensor 32 can acquire an image having a focused pattern without blur.

FIG. 4 is a diagram showing the configuration of the second embodiment of the inspection unit of the pattern inspection apparatus. The second embodiment of the present invention will be described with reference to FIG.
As in the case of FIG. 2, the reflective illumination means 21 is omitted, and the same components as those in FIG. 2 are denoted by the same reference numerals.
In this embodiment, a position where an image is acquired by a CCD line sensor can be measured by a distance sensor.

Unlike the first embodiment, the distance sensor 59 is provided on the imaging unit holding base 54 by being supported by a support 61 and is independent of the imaging unit 51.
Accordingly, the distance sensor 59 is scanned and moved in the width direction (X direction) of the film work W together with the imaging unit 51 by the imaging unit holding base 54, but does not move in the optical axis L direction (Z direction).

The distance sensor 59 is provided in a direction perpendicular to the longitudinal direction of the CCD line sensor 32 and in the forward direction (forward in the X direction) in which the imaging unit 51 is scanned and moved, and the distance to the surface of the workpiece W is measured at that position. To do.
The distance B from the position (sensor position) at which the distance sensor 59 measures the distance to the film work W to the position at which the pattern image is acquired by the CCD line sensor 32 (optical axis L of the imaging unit 52) is determined by the pattern inspection apparatus. The value B is stored in the control unit.

Also, an encoder or the like is attached to the scanning movement motor 55 and the optical axis direction movement motor 57 of the imaging unit holding base 54, and a mechanism for detecting the respective reference position (origin position) and the movement distance from the reference position (origin position). Is provided.
FIG. 5 is a diagram for explaining the operation of the image pickup unit in the second embodiment. Hereinafter, the operation for controlling the image pickup unit to the focal length with respect to the film work at the time of pattern image pickup will be described with reference to FIG.

As in the first embodiment, a flat plate on which a test pattern is formed is placed below the imaging unit 51 and the distance sensor 59, and the focal distance F at which the pattern image is formed on the CCD line sensor 32 by the distance sensor 59 is It is obtained and stored in the control unit of the apparatus.
The film work W to be inspected is set in the pattern inspection apparatus, the film work W is conveyed, and the part to be inspected stops at the inspection part of the apparatus.

As shown in FIG. 5A, the scanning unit motor 54 moves the imaging unit holding base 54 in the workpiece width direction (X direction).
However, the movement of the imaging unit holding base 54 needs to be started from a distance B or more before the inspection area where the pattern is formed.
The scanning direction (X direction) moving distance Xn (X0, X1, X2, X3...) Relative to the reference position (origin position X0) of the scanning movement motor 55 is detected by the encoder of the scanning movement motor 55 and is sent to the control unit 4. Sent.

Corresponding to the scanning direction (X direction) moving distance Xn (X0, X1, X2, X3...), The distance sensor 59 determines the distance An (A0, A1, A2, A3...) To the workpiece surface. Measure and send to the control unit 4 of the apparatus.
The control unit 4 compares the measured distance data An and the stored focal length F, and calculates a difference An−F = an (a0, a1, a2, a3...). The calculated an is stored in the storage unit of the control unit 4 corresponding to the moving distance Xn in the scanning direction (X direction) at that time.

As shown in FIG. 5B, the scanning movement of the imaging unit holding base 54 in the workpiece width direction continues, and the scanning direction (X direction) moving distance X is the distance between the distance sensor 59 and the optical axis L of the imaging unit. Reach B. That is, X = B = Xb.
At this time, the control unit 4 calls the stored A0-F value (a0) corresponding to X0, and picks up an image for a0 minutes from the origin position Z0 in the optical axis L direction (Z direction) of the imaging unit 51. The optical axis direction moving motor 57 is driven so that the unit 51 descends in the optical axis L direction.

Thereafter, the imaging unit 51 is scanned and moved in the workpiece width direction.
When the moving distance X of the imaging unit holding base 54 in the scanning direction (X direction) reaches X (b + n), the control unit 4 calls the stored An-F value an corresponding to the value of Xn, The optical axis direction moving motor 57 is driven so that the imaging unit 51 is lowered by an amount from the origin position Z0 in the optical axis L direction.

Thereby, the imaging unit 51 is maintained at the focal length F at the position where the pattern image is captured.
In the case of this embodiment, the distance to the workpiece surface can be measured by the distance sensor 59 with respect to the position where the image is acquired by the CCD line sensor 32, so that the amount of curvature of the film workpiece W is relative to the longitudinal direction of the workpiece. Even if they are different, the pattern to be inspected can be accurately focused.

In addition, since the distance sensor 59 is provided at an interval in the scanning movement direction (X direction) with respect to the imaging unit 51, until the imaging unit 51 reaches the position where the distance sensor 59 measures the distance to the workpiece surface. There is a time delay.
Since the control unit 4 can calculate the movement distance of the imaging unit 51 in the optical axis L direction (Z direction) during this grace period, the imaging unit can be moved to the focal length F even if the scanning (X direction) movement speed is increased. It is possible to obtain a pattern image that has been formed by moving the image to, and to shorten the inspection processing time.

FIG. 6 is a diagram showing the configuration of the third embodiment of the inspection unit of the pattern inspection apparatus. The third embodiment of the present invention will be described with reference to FIG.
In addition, the reflective illumination means 21 is abbreviate | omitted similarly to FIG. 2, and it has shown with the same code | symbol about the same structure as FIG.
In this embodiment, as in the second embodiment, the position where the image is acquired by the CCD line sensor can be measured by the distance sensor.

The distance sensor 59 is supported by a support 62 from the lens unit 53 in a direction orthogonal to the longitudinal direction of the CCD line sensor 32 and in a forward direction (front in the X direction) in which the imaging unit 51 is scanned and moved. Measure the distance to the workpiece surface at that position.
Therefore, as in the second embodiment, the distance to the workpiece can be measured with respect to the position where the image is acquired by the CCD line sensor, but the distance sensor is used together with the image pickup unit as in the first embodiment. Move in the direction of the optical axis.

Similarly to the second embodiment, the position at which the pattern image is acquired by the CCD line sensor 32 from the position (sensor position) at which the distance sensor 59 measures the distance to the film work W (optical axis L of the imaging unit 52). The interval B is set and measured when manufacturing the pattern inspection apparatus, and the value B is stored in the control unit.
The scanning movement motor 55 and the optical axis direction movement motor 57 are provided with a mechanism such as an encoder that can detect a reference position (origin position) and a movement distance from the reference position (origin position).

7 and 8 are diagrams for explaining the operation of the image pickup unit in the third embodiment. Hereinafter, the operation for controlling the image pickup unit to the focal length with respect to the film work at the time of pattern image pickup will be described with reference to FIG. To do.
As in the first and second embodiments, the test pattern is used, and the focal length F at which the pattern image is formed on the CCD line sensor 32 is obtained by the distance sensor 59 and stored in the control unit 4 of the apparatus.

The film work W to be inspected is set in the pattern inspection apparatus, the film work W is conveyed, and the part to be inspected stops at the inspection part of the apparatus.
As shown in FIG. 7A, the scanning unit motor 54 moves the imaging unit holding base 54 in the width direction (X direction) of the workpiece W. As in the second embodiment, the imaging unit holding base 54 is moved. As in the second embodiment, it is necessary to start the movement at a distance B or more before the pattern image acquisition start position.

The scanning direction (X direction) moving distance Xn (X0, X1, X2, X3...) Relative to the reference position (origin position X0) of the scanning movement motor 55 is detected by the encoder of the scanning movement motor 55 and is sent to the control unit 4. Sent.
Corresponding to the scanning direction (X direction) moving distance Xn (X0, X1, X2, X3...), The distance sensor 59 determines the distance An (A0, A1, A2, A3...) To the workpiece surface. Measure and send to the control unit 4 of the apparatus.

The control unit 4 compares the measured distance data An and the stored focal length F, and calculates a difference An−F = an (a0, a1, a2, a3...).
The calculated an is stored in the storage unit of the control unit 4 corresponding to the moving distance Xn in the scanning direction (X direction) at that time.
Also, the optical axis L direction (Z direction) movement distance Zn (Z0, Z1, Z2, Z3...) Relative to the reference position (origin position Z0) of the imaging unit holding base 54 is also set by the encoder of the optical axis direction movement motor 57. Detected and sent to the control unit 4.

The control unit 4 stores the movement distance Zn in the optical axis L direction (Z direction) in the storage unit corresponding to the scanning movement distance Xn.
As described above, the An-F value an and the optical axis L direction (Z direction) movement distance Zn are stored in correspondence with the scanning movement distance Xn of the imaging unit holding base 54.
As shown in FIG. 7B, the scanning movement of the imaging unit holding base 54 in the workpiece width direction continues, and the scanning direction (X direction) moving distance X is the distance between the distance sensor 59 and the optical axis L of the imaging unit. Reach B. That is, X = B = Xb.

At this time, the control unit 4 calls the A0-F value (a0) stored corresponding to X0 and the movement distance Z0 in the optical axis L direction (Z direction).
Then, the optical axis direction moving motor 57 is driven so that the imaging unit 51 descends in the optical axis L direction (Z direction) from the origin position Z0 of the imaging unit 51 in the optical axis L direction (Z direction) by a0 + Z0. To do.
In FIG. 7B, Z0 = 0, and the moving amount of the imaging unit 51 in the Z direction is a0.

In FIG. 7B, since the amount of movement in the scanning direction (X direction) is Xb, corresponding to Xb, the difference ab from the focal length F obtained from the distance data ab at this time, and Z The direction moving distance Zb = a0 is stored.
Thereafter, the imaging unit 51 is scanned and moved in the workpiece width direction.
When the moving distance X in the scanning direction (X direction) of the imaging unit holding base 54 becomes X (b + n), the control unit 4 stores the An-F value an and the optical axis stored corresponding to the value of Xn. The movement distance Zn in the L direction (Z direction) is called, and the optical axis direction movement motor 57 is driven so as to move the imaging unit 51 in the optical axis L direction from the origin position Z0 of the imaging unit holding base 54 by an + Zn. .

That is, as shown in FIG. 8C, for example, when the imaging unit holding base 54 further moves the distance B from Xb and reaches Xm, the control unit 4 stores the value corresponding to the value of Xb. The Ab-F value ab and the optical axis L direction (Z direction) movement distance Zb (= a0 + Z0) are called, and the optical axis direction moving motor 57 is moved so that the imaging unit 51 moves in the optical axis L direction by ab + Zb. Drive.
Thereby, the imaging unit 51 is maintained at the focal length F.

Thereby, the imaging unit 51 is maintained at the focal length F at the position where the pattern image is captured.
In the case of the present embodiment, as in the second embodiment, the distance to the workpiece surface can be measured by the distance sensor 59 with respect to the position where the image is acquired by the CCD line sensor 32. However, even if it differs in the longitudinal direction of the workpiece, the pattern to be inspected can be focused with high accuracy.

  The distance sensor 59 is provided with an interval in the scanning movement direction (X direction) with respect to the imaging unit 51, and the time until the imaging unit 51 reaches the position where the distance sensor 59 measures the distance to the workpiece surface. Since the control unit 4 can calculate the movement distance of the imaging unit 51 in the optical axis L direction (Z direction) during this delay time, the scanning (X direction) movement speed is increased. In addition, the imaging unit can be moved to the focal length F, and the formed pattern image can be acquired, so that the inspection processing time can be shortened.

  In the above embodiment, the mechanism and operation for moving the imaging unit 51 in the direction of the optical axis L in order to maintain the imaging unit 51 at the focal position F with respect to the film work W have been described. The position in the direction of the axis L may be fixed, and the film work W may be moved in the direction of the optical axis L, and the same effect can be obtained.

  In particular, when a high resolution is required, the imaging unit 51 may become heavier due to an increase in the number of lenses of the lens unit 53. In such a case, the imaging unit 51 is moved in the optical axis L direction. Rather than moving the film work W, the structure of the drive mechanism and the like is simplified.

FIG. 9 is a diagram showing the configuration of the fourth embodiment of the inspection unit of the pattern inspection apparatus, and an embodiment in which the film work is moved in the optical axis direction of the imaging unit will be described with reference to FIG. In the figure, the same components as those in the above embodiment are denoted by the same reference numerals.
Similar to the second embodiment, the distance sensor 59 is supported by the support 61 on the imaging unit holding base 54 and is in a direction perpendicular to the longitudinal direction of the CCD line sensor 32, and the imaging unit 51 is scanned and moved. The distance to the surface of the work W is measured at that position.

  The distance from the position where the distance sensor 59 measures the distance to the film work W (sensor position) to the position where the pattern image is acquired by the CCD line sensor 32 (optical axis L of the imaging unit 52) is determined by pattern inspection. The setting is measured when the device is manufactured, and stored in the control unit.

Unlike the first to third embodiments, the imaging unit holding base 54 is provided with only the scanning movement motor 55, and the scanning movement motor 55 moves the imaging unit holding base 54 along the rail 56. The imaging unit 51 scans and moves in the width direction (X direction) of the film work W.
An encoder or the like is attached to the scanning movement motor 55, and a reference position (origin position) in the X direction and a movement distance from the reference position (origin position) are detected.

Work edge holding mechanisms 90 that hold both ends (edges) of the workpiece W and apply tension by pulling the workpiece W in the width direction are provided on one plate 91 on both sides in the width direction of the film workpiece W of the inspection unit 5. It has been. The work edge holding mechanism 90 has a detailed configuration example shown in, for example, Japanese Patent Application No. 2004-197595.
The plate 91 is provided with a plate moving mechanism 92 that moves the plate 91 in the direction of the optical axis L (Z direction) of the imaging unit 51. By moving the plate 91, the work edge holding mechanism 90 is moved in the direction of the optical axis L ( Z direction).

Therefore, the film work W approaches or separates from the imaging unit 51 by moving in the optical axis L direction (Z direction) while the work edge holding mechanism 90 holds the film work W.
Next, an operation for controlling the film work to the focal length with respect to the imaging unit at the time of pattern imaging will be described.

As in the above embodiment, a flat plate on which a test pattern is formed is placed below the imaging unit 51 and the distance sensor 59, and the focal length at which the pattern image is formed on the CCD line sensor 32 is obtained by the distance sensor 59. It is stored in the control unit of the apparatus.
The film work W to be inspected is set in the pattern inspection apparatus, the film work W is conveyed, and the part to be inspected stops at the inspection part of the apparatus.

The work edge holding mechanism 90 holds both ends (edges) of the film work W in the width direction. The workpiece edge holding mechanism 90 moves slightly in the width direction of the workpiece W, applies tension to the width direction of the workpiece W, and reduces slack generated in the width direction of the workpiece W.
The scanning movement motor 55 operates to move the imaging unit holding base 54 in the workpiece width direction (X direction).

As in the second embodiment, the scanning movement (X direction) movement distance with respect to the reference position (origin position) of the scanning movement motor 55 is detected by the encoder of the scanning movement motor 55 and sent to the control unit 4.
Corresponding to the moving distance in the scanning direction (X direction), the distance sensor 59 measures the distance to the workpiece surface and sends it to the control unit 4 of the apparatus.

The control unit 4 compares the measured distance data with the stored focal length, calculates the difference, and corresponds to the moving distance in the scanning direction (X direction) at that time, the storage unit of the control unit 4 To remember.
When the imaging unit 51 moves in the X direction and reaches a position where the difference from the focal length is calculated, the control unit 4 calls the difference from the stored focal length and drives the plate moving mechanism 92. The plate 91 is moved in the optical axis L direction (Z direction) of the imaging unit 51 by a distance corresponding to the difference from the focal length.

  As the plate 91 moves, the work edge holding mechanism 90 and the film work W held thereon move in the optical axis L direction (Z direction) of the image pickup unit 51, and as a result, the film work W moves to the image pickup unit 51. Is located at the focal length.

  Thereafter, according to the scanning movement of the imaging unit 51 in the workpiece width direction (X direction), the distance sensor 59 measures the distance to the workpiece surface, and calculates and stores the difference between the distance measured by the control unit 4 and the focal length. By repeating the movement of the film work W in the optical axis L direction (Z direction) by the plate moving mechanism 92, the film work W is maintained at the focal length with respect to the imaging unit 51 at the position where the pattern image is taken.

It is a figure which shows schematic structure of the pattern inspection apparatus of the film work which is an Example of this invention. It is a figure (1st Example) which shows the detailed structure of the test | inspection part of a pattern inspection apparatus. It is a figure explaining operation | movement of the imaging unit in a 1st Example. It is a figure (2nd Example) which shows the detailed structure of the test | inspection part of a pattern inspection apparatus. It is a figure explaining operation | movement of the imaging unit in a 2nd Example. It is a figure (3rd Example) which shows the detailed structure of the test | inspection part of a pattern inspection apparatus. It is FIG. (1) explaining operation | movement of the imaging unit in a 3rd Example. It is FIG. (2) explaining operation | movement of the imaging unit in a 3rd Example. It is a figure (4th Example) which shows the detailed structure of the test | inspection part of a pattern inspection apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Film work conveyance mechanism 11 Delivery reel 12 Take-up reel 21 Reflection illumination means 22 Transmission illumination means 3 Marker part 4 Control part 5 Inspection part 51 Imaging unit 52 CCD line sensor 53 Lens unit 54 Imaging unit holding stand 55 Scanning movement motor 56 Rail 57 optical axis direction moving motor 58 shaft 59 distance sensor 61, 62 support 71 conveying roller 72 brake roller 80 scanning means 90 work edge holding mechanism 91 plate 92 plate moving mechanism F focal length of imaging unit W film work L optical axis of imaging unit

Claims (3)

In a film work pattern inspection apparatus that scans an image pickup unit in the width direction of a long film work, acquires and inspects an image of a pattern formed on the film work,
The imaging unit includes an imaging element that is a line sensor arranged along the longitudinal direction of the film work, and an optical element that projects a pattern on the film work onto the imaging element.
A scanning movement mechanism for moving the imaging unit in the width direction of the film work, an optical axis direction moving mechanism for moving the imaging unit in the optical axis direction of the imaging unit, and a scanning movement mechanism together with the imaging unit. A distance sensor that measures the distance to the film work, and a controller that drives the optical axis direction moving mechanism based on distance information from the distance sensor and maintains the imaging unit at a focal length with respect to the film work. A film work pattern inspection apparatus comprising: In a film work pattern inspection apparatus that scans an image pickup unit in the width direction of a long film work, acquires and inspects an image of a pattern formed on the film work,
The imaging unit includes an imaging element that is a line sensor arranged along the longitudinal direction of the film work, and an optical element that projects a pattern on the film work onto the imaging element.
A scanning movement mechanism that moves the imaging unit in the width direction of the film work, a work holding mechanism that holds both ends of the film work in the width direction, and an optical axis direction that moves the work holding mechanism in the optical axis direction of the imaging unit A moving mechanism, a distance sensor that measures the distance to the film work while scanning and moving together with the imaging unit by the scanning movement mechanism, and the work holding mechanism holds the film work based on distance information from the distance sensor. A film work pattern inspection apparatus comprising: a controller that drives the optical axis direction moving mechanism in a state to keep the imaging unit at a focal length with respect to the film work. 3. The distance sensor according to claim 1, wherein the distance sensor is provided in a direction perpendicular to a longitudinal direction of the CCD line sensor and in a forward direction in which the imaging unit is scanned and moved. Filmwork pattern inspection equipment.

Images