KR101808262B1 - Apparatus and method for measuring straightness - Google Patents

Apparatus and method for measuring straightness Download PDF

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Publication number
KR101808262B1
KR101808262B1 KR1020160022834A KR20160022834A KR101808262B1 KR 101808262 B1 KR101808262 B1 KR 101808262B1 KR 1020160022834 A KR1020160022834 A KR 1020160022834A KR 20160022834 A KR20160022834 A KR 20160022834A KR 101808262 B1 KR101808262 B1 KR 101808262B1
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South Korea
Prior art keywords
image
photographing
straightness
photographing unit
photographed image
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KR1020160022834A
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Korean (ko)
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KR20170100360A (en
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허진
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주식회사 이오테크닉스
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Priority to KR1020160022834A priority Critical patent/KR101808262B1/en
Priority to PCT/KR2016/010140 priority patent/WO2017146330A1/en
Priority to TW105129927A priority patent/TWI626421B/en
Publication of KR20170100360A publication Critical patent/KR20170100360A/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
    • B23K26/03—Observing, e.g. monitoring, the workpiece
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
    • B23K26/03—Observing, e.g. monitoring, the workpiece
    • B23K26/032—Observing, e.g. monitoring, the workpiece using optical means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
    • B23Q17/00—Arrangements for observing, indicating or measuring on machine tools
    • B23Q17/24—Arrangements for observing, indicating or measuring on machine tools using optics or electromagnetic waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
    • G01B11/04—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness specially adapted for measuring length or width of objects while moving
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
    • G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
    • G01B11/06—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material
    • G01B11/0691—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness for measuring thickness ; e.g. of sheet material of objects while moving
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/08—Measuring arrangements characterised by the use of optical techniques for measuring diameters
    • G01B11/10—Measuring arrangements characterised by the use of optical techniques for measuring diameters of objects while moving

Abstract

A straightness measuring apparatus and method are disclosed. The disclosed straightness measuring method includes the steps of obtaining a photographed image of a reference line displayed on an object while changing a photographing position along a processing direction of the object and measuring a straightness of the processing direction from a position of the reference line indicated in the photographed image .

Description

[0001] Apparatus and method for measuring straightness [0002]

To an apparatus and a method for measuring the straightness of a direction in which an object is processed.

The machining process of forming a marking pattern on an object or cutting an object includes mechanical machining and laser machining. Generally, laser processing refers to a process of processing the shape and physical properties of a workpiece surface by scanning a laser beam on the surface of the workpiece.

In order to improve the machining quality of the object, it is important that the position where the mechanical pressure is irradiated or the irradiation position of the laser beam moves accurately along the line to be machined. In a typical machining process, the object can be linearly moved by the moving stage or the machining position can be changed while the machining equipment is moving linearly.

However, when the machining position is changed, the movement trajectory of the moving stage can not accurately follow the ideal straight line due to the out-of-vibration mechanical tolerance. The extent to which the line due to machining deviates from the straight line is called the straightness of the machining direction. In the processing step of the object, a process of measuring the straightness and inspecting the machining error is required.

According to the exemplary embodiment, the accuracy of the straightness measurement in the direction of processing the object can be increased.

In one aspect,

A method for measuring a straightness of a direction in which an object is processed,

Obtaining a photographed image of a reference line displayed on an object while changing a photographing position along a processing direction of the object; And

Measuring a straightness of the machining direction from a position of the reference line in the shot image,

The step of acquiring the captured image is provided so that the line width of the reference line appearing in the captured image according to the movement of the taken position is smaller than the resolution of the photographing unit.

Wherein,

The line width of the reference line may be smaller than half the resolution of the photographing unit.

The step of acquiring the captured image includes:

The exposure time for photographing the photographed image and the speed for moving the photographed position may satisfy Equation (1).

V * E * tan? ≪ P / M Equation 1

(V = Machining position moving speed, E = Exposure time, θ = Angle between machining direction and reference line, P = Pixel size, M = Magnification)

The step of acquiring the captured image includes:

The first direction size and the second direction size of the photographed image may be different from each other.

The step of acquiring the captured image includes:

The photographed image can be photographed as a line image.

Wherein measuring the straightness comprises:

Converting the captured image into a binarized image based on the brightness of the captured image, and identifying the position of the reference line from the binarized image.

Wherein the straightness measuring method further comprises: generating a pulse signal as the photographing position changes,

The step of acquiring the captured image may be synchronized with the pulse signal to obtain the captured image.

In another aspect,

An apparatus for measuring a straightness of a direction in which an object is processed,

A photographing unit for acquiring a photographing image of reference lines displayed on an object;

A moving stage for moving a photographing position of the photographing unit along a processing direction of the object;

And a processor for measuring a straightness of the processing direction from a position of a reference line indicated in the captured image,

The processor rotates the object such that the line width of the reference line appearing in the captured image as the movement of the photographing position is smaller than the resolution of the photographing unit.

The processor comprising:

It is possible to control the photographing section so that the line width of the reference line is smaller than 1/2 of the resolution of the photographing section.

The processor comprising:

The photographing unit and the moving stage can be controlled so that the speed at which the photographing position moves and the exposure time of the photographing unit satisfy Equation (1).

V * E * tan < P / M.

(V = Machining position moving speed, E = Exposure time, θ = Angle between machining direction and reference line, P = Pixel size, M = Magnification)

Wherein,

The first direction size and the second direction size of the photographed image may be different from each other.

Wherein,

The photographed image can be photographed as a line image.

The processor comprising:

The captured image may be converted into a binarized image based on the brightness of the captured image.

Wherein the straightness measuring apparatus further comprises an encoder for generating pulse signals as the photographing position changes,

The photographing unit may be synchronized with the pulse signal to obtain the photographed image.

According to the embodiment, the reference line displayed on the object can be photographed while the photographing position moves along the processing direction. Therefore, the straightness measurement speed can be faster than when the photographing position is stopped. In addition, it is possible to prevent the position of the reference line from becoming unclear due to the blurring phenomenon of the image caused by the photographing position. Therefore, the accuracy of the straightness measurement can be increased.

Fig. 1 is a diagram exemplarily showing a laser processing step of an object.
2 is a view showing an exemplary surface of an object.
3 is a schematic view of a straightness measuring apparatus according to an exemplary embodiment.
4 is a flowchart showing a straightness measurement method using the straightness measuring apparatus shown in FIG.
5 is a diagram for explaining the line width variation of the reference line described above.
6 is a view showing that the position of the reference line changes as the photographing position moves along the processing direction during the exposure time.
7 is a diagram showing an increase in the line width of the reference line in the photographed image.
8 is a view showing an example of a photographed image photographed by the photographing section.
9 is a diagram exemplarily showing a plurality of captured images received by the processor.
10 is a diagram showing an example of a photographed image.
11 is a diagram showing the binarization of the photographed image shown in Fig.
FIG. 12 shows an image obtained by converting the shot image shown in FIG. 10 into a predetermined plurality of brightness values.

In the following drawings, like reference numerals refer to like elements, and the size of each element in the drawings may be exaggerated for clarity and convenience of explanation. On the other hand, the embodiments described below are merely illustrative, and various modifications are possible from these embodiments.

The terms first, second, etc. may be used to describe various elements, but the elements should not be limited by terms. Terms are used only for the purpose of distinguishing one component from another.

The singular expressions include plural expressions unless the context clearly dictates otherwise. Also, when an element is referred to as "comprising ", it means that it can include other elements as well, without departing from the other elements unless specifically stated otherwise.

Also, the terms &quot; part, &quot; &quot; module, &quot; and the like, which are described in the specification, refer to a unit that processes at least one function or operation.

Fig. 1 is a diagram exemplarily showing a laser processing step of the object 10. Fig.

Referring to FIG. 1, an object 10 may be seated on a chuck 20. The light source 112 can irradiate a laser beam toward the object 10. The position at which the light source 112 irradiates the object 10 with the laser beam can be changed by the movement stage 130. [ The moving stage 130 can move the chuck 20 on which the object 10 is placed along a straight line (y-axis direction). As the moving stage 130 moves the chuck 20, the object 10 moves and the laser marking pattern can be formed linearly on the object 10.

Although the laser processing step is exemplarily shown in Fig. 1, the processing steps to which the embodiment can be applied are not limited thereto. For example, the embodiments described herein can also be applied to mechanical grooving, cutting processes, and the like.

The object 10 may include a wafer, a semiconductor chip, and the like as an object to be imaged, but is not limited thereto. In order to properly process the object 10, the direction in which the object 10 is to be machined and the machining position of the object 10 must move in the same direction. Therefore, the direction in which the object 10 is arranged on the chuck 20 can be aligned to the processing direction.

Fig. 2 is a diagram exemplarily showing the surface of the object 10. Fig.

Referring to FIG. 2, the object 10 may include a plurality of semiconductor chips 11 arranged in a lattice pattern. Identifiable reference lines (L, L ') may be marked on the surface of the object (10). The reference lines L and L 'may be the same straight line as the line along which the material is to be divided L or may be in the form of a line segment as the edge L' of the semiconductor chip 11. That is, in the photographed image, the reference lines L and L 'may appear as images in the form of a straight line or a line segment.

A laser beam may be irradiated along some of the reference lines L and L 'of the object 10 in the laser processing step. When the laser beam is irradiated along the reference lines L and L ', the plurality of semiconductor chips 11 included in the object 10 can be separated individually. The separated semiconductor chip 11 can be packaged by resin packaging.

In order to prevent the semiconductor chip 11 from being damaged in the processing step, the line along which the object is intended to be cut (L) in the moving direction (y-axis direction) of the laser beam and the reference lines L and L ' Therefore, by adjusting the arrangement angle of the object 10, the reference lines L and L 'of the object 10 and the processing direction of the laser beam (y-axis direction) can be made close to parallel.

However, even if the arrangement direction of the object 10 is adjusted on the basis of the reference lines L and L ', the laser beam can be irradiated to a point off the line along which the object is intended to be cut L. [ For example, the movement direction (y-axis direction) of the position where the laser beam is irradiated may not be perfectly parallel to the reference lines L and L 'due to an error in the aligning process. In addition, the direction in which the movable stage 130 moves the chuck 20 may not be perfectly straight. There may be defects in the equipment itself of the moving stage 130 and vibrations may be generated in the moving stage 130 in the direction perpendicular to the moving direction (x-axis direction) . Due to defects in the equipment described above or due to vibrations occurring during the movement, the irradiation position of the laser beam may not move along a perfect straight line as shown in Fig.

The difference between the actual machining direction and the ideal straight line is called the straightness of the machining direction. In normal cases, straightness may not be zero. If the straightness becomes too large, the processing quality is degraded, and the semiconductor chip 11 included in the object 10 may be damaged by the laser beam.

3 is a view schematically showing an apparatus for measuring straightness 100 according to an exemplary embodiment.

3, the straightness measuring apparatus 100 according to the exemplary embodiment includes a photographing unit 110 for obtaining an image of a reference line L and L 'displayed on an object 10, A moving stage 130 for moving a photographing position of the photographing unit 110 along a processing direction of the photographing unit 110 and a processor for measuring a straightness of the processing direction from a position of a reference line L and L ' 140).

The photographing unit 110 can photograph the surface of the object 10. The photographing unit 110 can acquire the photographed image a plurality of times while the photographing position is changed by the moving stage 130. [ The photographing unit 110 may transmit the acquired photographing image information to the processor 140. [ In FIG. 3, the photographing unit 110 and the processor 140 are shown as separate components, but the embodiment is not limited thereto. For example, the processor 140 may be embedded in the photographing unit 110. [ In addition, the processor 140 and the photographing unit 110 may share some hardware resources.

The photographing unit 110 can receive the light reflected by the object 10. The photographing unit 110 may include a light source 112 to secure a sufficient amount of light to be received. The photographing unit 110 can illuminate the object 10 with the illumination light using the light source 112 to secure a sufficient light reception amount. The straightness measuring apparatus 100 may further include a condensing optical system 114 provided between the photographing unit 110 and the object 10. [ The condensing optical system 114 can condense the light irradiated from the light source 112 to the photographing position of the photographing unit 110 to further increase the light receiving amount of the photographing unit 110. [ Further, the power consumption of the light source 112 can be reduced by the condensing optical system 114. [

The moving stage 130 can change the position at which the photographing unit 110 photographs the object 10. [ The moving stage 130 can change the photographing position of the photographing unit 110 by changing the relative position between the photographing unit 110 and the object 10 in the y axis direction. For example, the moving stage 130 can move the photographing position of the photographing unit 110 by moving the chuck 20 on which the object 10 is placed. However, the embodiment is not limited thereto. The moving stage 130 may change the photographing position of the photographing unit 110 by changing the position of the photographing unit 110 or may move both the photographing unit 110 and the object 10. [

The processor 140 may control the photographing unit 110 and the movement stage 130. [ The processor 140 may control the exposure time of the photographing unit 110. [ Also, it is possible to control the time interval at which the photographing unit 110 photographs an image. For example, while the moving stage 130 changes the photographing position at a constant speed, the processor 140 may cause the photographing section 110 to photograph the image at regular time intervals. The processor 140 may derive the distance variation of the photographing position from the time interval information between the photographed images. The processor 140 may control whether the moving stage 130 is operated and the speed at which the moving stage 130 moves the shooting position.

4 is a flowchart showing a straightness measuring method using the straightness measuring apparatus 100 shown in FIG.

4, a straightness measuring method according to an embodiment includes a step 1110 of obtaining an image of a reference line L, L 'displayed on an object 10 while changing a photographing position along a laser processing direction, And measuring the straightness of the machining direction from the position of the reference line (L, L ') shown in the shot image (step 1120).

In step 1110, the photographing unit 110 can photograph the surface of the object 10. The photographing unit 110 can photograph the reference lines (L, L ') displayed on the object 10. The moving stage 130 can move the photographing position of the photographing unit 110. [ The photographing unit 110 can acquire a photographed image a plurality of times while the photographing position moves in the y-axis direction. The photographing unit 110 can photograph the object 10 while the moving stage 130 changes the photographing position. In this case, the time taken to acquire the shot image at the plurality of shooting positions can be shortened as compared with the case where the moving stage 130 is stopped.

The processor 140 may control the exposure time of the photographing unit 110 and the speed at which the movement stage 130 moves the photographing position. The processor 140 may control the exposure time and speed so that the line widths of the reference lines L and L 'appearing in the shot image become smaller than the resolution of the shooting unit 110. [ Hereinafter, the reference lines L and L 'due to the blur of the photographed image will be described with respect to an increase in line width.

If the machining direction is exactly parallel to the reference lines L and L ', the line width of the reference lines L and L' may not change even if the photographing position moves in the machining direction. However, as described above, the machining direction may not exactly coincide with the reference lines L and L 'due to the deviation of the arrangement angle of the object 10. The direction in which the movable stage 130 moves the object 10 due to the vibration or the like generated in the movable stage 130 may not exactly coincide with the y axis, ).

5 is a diagram for explaining the line width variation of the above-described reference lines (L, L ').

Referring to Fig. 5, the machining direction k and the reference lines L, L 'may not be completely parallel. The angle θ between the processing direction k and the reference lines L and L 'may vary depending on the arrangement angle of the object 10 and the magnitude of vibration generated during the operation of the moving stage 130. When the object 10 is photographed while changing the photographing position along the processing direction k, the positions of the reference lines L and L 'may be changed during the exposure time of the photographing unit 110. Therefore, the effect of blurring of the reference lines L and L 'in the photographed image due to the movement of the photographing position may occur.

6 is a view showing that the positions of the reference lines L and L 'change as the photographing position moves along the processing direction k during the exposure time.

Referring to FIG. 6, the processing direction k and the reference lines L and L 'may not be parallel to each other. The photographing unit 110 can photograph the object 10 for a predetermined exposure time. During the exposure time, the relative positions of the object 10 and the photographing unit 110 are changed, and the photographing position can be moved by the distance d along the processing direction k. The positions of the reference lines L and L 'can be moved by a distance w in the direction perpendicular to the processing direction k while the photographing position moves by the distance d. As a result, the reference lines L and L 'are blurred in the photographed image, and the line widths of the reference lines L and L' may increase.

FIG. 7 is a diagram showing that the line widths of the reference lines (L, L ') in the photographed image are increased.

Referring to FIG. 7, the line width of the reference lines L and L 'can be increased by the effect that the photographed image of the photographing unit 110 becomes blurred. The reference lines L and L 'can move in the direction perpendicular to the processing direction k as the photographing position changes during the exposure time of the photographing unit 110. [ As a result, the positions of the reference lines L and L 'in the photographed image are not precisely specified, and the line widths of the reference lines L and L' can be increased.

The line width of the reference lines L and L 'depends on the angle between the processing direction k and the reference lines L and L', the exposure time of the photographing unit 120 and the speed at which the photographing position moves . For example, the line widths of the reference lines L and L 'may become larger as the exposure time of the photographing unit 120 increases, and as the moving speed of the photographing position increases.

If the line widths of the reference lines L and L 'become excessively large, it may not be easy to determine the exact position of the reference lines L and L' in the shot image. Reference in shot image

 If the position error of the lines L and L 'becomes large, the straightness value of the machining direction k read from the shot image may be distorted.

The straightness measuring method according to the embodiment may make the line width of the reference line appearing in the photographed image smaller than the resolution of the photographing unit 110 as the photographing position moves in step 1110. [ Here, the resolving power of the photographing unit 110 may be determined according to the pixel size and the magnification of the photographing unit 110. Illustratively, the resolution of the photographing unit 110 can be determined by Equation (1).

Figure 112016018827018-pat00001

In Equation (1), r denotes the resolution of the photographing unit 110. In addition, P means the size of a pixel, which may mean the length or width of the pixel. And M denotes a magnification of the photographing unit 110. [ In the case of a camera device used in a laser processing process, the resolution may be on the order of about 0.2 μm to 0.3 μm. However, the above numerical values are merely illustrative and not limitative of the embodiments.

The processor 140 adjusts the exposure time of the photographing unit 110 and the speed at which the movement stage 130 moves the photographing position so that the line width of the reference lines L and L ' (R) of the light-shielding film. When the line widths of the reference lines L and L 'become smaller than the resolution r of the photographing unit 110, errors in the position of the reference lines L and L' in the photographed image can be reduced. If the errors of the positions of the reference lines L and L 'are reduced, the measurement error of the straightness can also be reduced.

Illustratively, the processor 140 adjusts the exposure time of the photographing unit 110 and the speed at which the movement stage 130 moves the photographing position so that the line width of the reference lines L and L ' Can be made smaller than half of the resolution (r) of the part (110). When the line width of the reference lines L and L 'becomes smaller than half of the resolution r of the photographing unit 110, the reference lines L and L' in the photographed image can be displayed in only one pixel. Therefore, it is possible to substantially eliminate the error caused by the blurring effect of the image due to the dynamic photographing.

The processor 140 may cause the exposure time E of the photographing unit 110 and the speed V at which the moving stage 130 moves the photographing position to satisfy Equation 2.

Figure 112016018827018-pat00002

In the equation (2), V denotes the moving speed of the processing position, E denotes the exposure time,? Denotes the angle between the processing direction k and the reference lines L and L ', P denotes the pixel size, and M denotes the magnification.

Referring to Equation (2), V * E may correspond to the distance d shown in Fig. That is, the distance d at which the photographing position moves in the processing direction k during the exposure time E may be equal to the product of the exposure time E and the moving speed V of the photographing position. V * E * tan? May correspond to the distance w shown in FIG. In other words, the distance w that the positions of the reference lines L and L 'move in the direction perpendicular to the machining direction k during the exposure time E corresponds to the distance d and the machining direction k, (L, L '). The distance w of the position of the reference lines L and L 'in the direction perpendicular to the processing direction k during the exposure time E corresponds to the resolution r = P / M). The distance w may be approximately equal to the line width of the reference lines (L, L ') represented by the blurring effect of the image. Therefore, the line widths of the reference lines L and L 'can be made smaller than the resolving power of the photographing unit 110.

In a typical laser processing process, tan? May have a value in the range of approximately 0 to 10 -4 . Thus, when the resolution P / M is approximately 0.2 [mu] m to 0.3 [mu] m, the velocity V and the exposure time E are approximately

Figure 112017008038797-pat00003
Can be satisfied. However, if the speed V for moving the photographing position is too small, it is difficult to measure the high-speed straightness, so that the exposure time E can satisfy approximately E <2 ms. The numerical values are merely illustrative, and are not intended to limit the embodiments.

8 is a view showing an example of a photographed image photographed by the photographing unit 110. As shown in Fig.

Referring to FIG. 8, reference lines (L, L ') may appear in the captured image of the photographing unit 110. The line width of the reference lines L and L 'may be smaller than the resolution of the photographing unit 110 in the x-axis direction. Thus, the x-axis position of the reference lines L, L 'can be defined by one pixel position in the captured image.

The photographing unit 110 can acquire a photographing image as shown in FIG. 8 every time the photographing position is changed. The straightness of the processing direction can be determined according to how the position of the reference lines L and L 'is shifted in the x-axis direction in the plurality of shot images. That is, since it is important to how far the reference lines L and L 'in the captured image are shifted in the x-axis direction, the need to acquire the entire image of the object 10 in the y-axis direction may be small. Therefore, the photographed image captured by the photographing unit 110 may have different sizes in the x-axis direction and the y-axis direction.

For example, the size of the photographed image in the y-axis direction (the direction in which the photographing position moves by the moving stage 130) may be smaller than the size in the x-axis direction. The photographing unit 110 may acquire an image by photographing a partial frame instead of photographing all of the entire frame. The photographing unit 110 can photograph only a part of the frame of the object 10 in the direction in which the photographing position moves (y axis direction) by the moving stage 130. [

When the photographing unit 110 photographs only some frames in the y-axis direction, the number of times that the photographing unit 110 can photograph an image per hour can be increased. Therefore, it is easy to control the exposure time E of the photographing unit 110 to be small. In addition, by acquiring more images per unit time, the positional change of the reference lines L and L 'can be seen in shorter time intervals. If the photographing section 110 acquires more photographed images in shorter time intervals, the accuracy of the straightness measurement in the processing direction can be further enhanced.

The photographing unit 110 may photograph the line image illustratively. That is, only one pixel may be provided in the y-axis direction in the captured image. When the photographing unit 110 photographs a line image, since only one pixel is provided in the y-axis direction, the configuration of the photographing unit 110 can be simplified. Further, as the arrangement of the light receiving elements included in the photographing unit 110 in the y-axis direction is facilitated, the light receiving area per unit pixel can be widened. As the light receiving area per unit pixel of the photographing unit 110 becomes wider, the sharpness of the photographed image can be increased.

Referring again to FIG. 4, in step 1120, the processor 140 may measure the straightness of the processing direction k from the positions of the reference lines L and L 'shown in the plurality of shot images. The processor 140 may receive a plurality of photographed images from the photographing unit 110. [ The plurality of photographed images may be photographed at different photographed positions. The photographing unit 110 can acquire a captured image of the object 10 and transmit the captured image to the processor 140 while the relative position between the light source 112 and the object 10 is changed by the moving stage 130. [ The processor 140 may measure the straightness of the processing direction k from the positions of the reference lines L and L 'shown in each of the plurality of shot images.

FIG. 9 is a diagram exemplarily showing a plurality of captured images received by the processor 140. FIG.

Referring to FIG. 9, the processor 140 may receive a plurality of photographed images from the photographing unit 110. FIG. For example, the processor 140 may identify the location of the reference lines L and L 'in the first through third images a, b, and c, respectively. 9, in the first image (a) and the second image (b), the positions of the reference lines L and L 'may hardly change. However, in the third image (c), the positions of the reference lines L and L 'can be shifted by? X. The processor 140 determines whether the photographing position is moved by the moving stage 130 while the x-axis direction shift amount x of the reference lines L and L 'and the first to third images a, b, the straightness of the machining direction k can be found from the ratio of the distance moved in the y-axis direction.

In order for the processor 140 to correctly determine the straightness, the photographing position is set so that the first to third images a, b, and c are photographed as well as the x-axis positional shift amount x of the reference lines L and L ' Distance information moved in the y-axis direction may also be needed.

The photographing unit 110 can photograph the object 10 every time the photographing position is changed by a predetermined distance by the moving stage 130 so that the processor 140 can easily obtain the moving distance information of the photographing position. For example, the photographing unit 110 can photograph the object 10 in synchronization with a pulse signal generated whenever the moving stage 130 moves the object 10 or the photographing unit 110 by a predetermined distance.

Referring again to FIG. 3, the straightness measuring apparatus 100 according to the embodiment may further include an encoder 135 that generates a pulse signal whenever the photographing position changes by a predetermined distance. Encoder 135 may be coupled to moving stage 130 to sense the mechanical movement of moving stage 130. The encoder 135 can sense the distance that the moving stage 130 moves the light source 112 or the object 10. [ The encoder 135 can generate a pulse signal whenever the photographing position of the photographing unit 110 is moved by a predetermined interval by the moving stage 130. [ The pulse signal generated by the encoder 135 may be transmitted to the photographing unit 110.

The photographing unit 110 can be synchronized in operation by the pulse signal of the encoder 135. [ For example, when the photographing unit 110 receives the pulse signal, it can photograph the object 10 during the exposure time E. Since the photographing section 110 is synchronized by the pulse signal of the encoder 135, the photographing image can be obtained every time the photographing position changes by a certain distance in the y-axis direction. Then, the processor 140 may derive the amount of change of the photographing position from the number of the photographing images while the photographing images are taken.

In FIGS. 8 and 9, it is relatively easy to identify the reference lines L and L 'in the photographed image. However, it may be difficult to identify the reference lines L and L 'depending on the quality of the photographed image.

10 is a diagram showing an example of a photographed image.

Referring to FIG. 10, it may not be easy to identify the reference lines L and L 'when the brightness change of the shot image is small. If it is not easy for the processor 140 to identify the reference lines L and L ', it may not be easy to measure the straightness from the position change of the reference lines L and L'.

In order to solve the problem shown in FIG. 10, the processor 140 may binarize the photographed image received from the photographing unit 110 based on brightness. The processor 140 can differentiate into a region where the brightness is higher than a predetermined reference value and a region where the brightness is not in the photographed image. The processor 140 may treat the region where the brightness is higher than the reference value in the shot image as white and process the region where the brightness is lower than the reference value as black.

11 is a diagram showing the binarization of the photographed image shown in Fig.

Referring to FIG. 11, the processor 140 may generate a binarized image in which the shot image shown in FIG. 10 is binarized based on brightness. In the binarized image, it is easy to distinguish between a region where the brightness is higher than the reference value and a region where the brightness is lower than the reference value. Therefore, in the binarized image, the positional identification of the reference lines L and L 'can be facilitated.

In Fig. 11, the processor 140 binarizes the photographed image based on brightness, but the embodiment is not limited thereto. The processor 140 may discontinuously display the brightness of the photographed image according to a predetermined brightness interval. For example, the processor 140 may uniformly display the area having the brightness value in the first range in the shot image as the first brightness and the area having the brightness value in the second range as the second brightness, And the area having the brightness value in the third range may be unified with the third brightness. That is, the processor 140 may display the photographed image as a brightness value of n (n is a natural number).

FIG. 12 shows an image obtained by converting the shot image shown in FIG. 10 into a predetermined plurality of brightness values.

Referring to FIG. 12, the photographed image may be displayed with a plurality of brightness values. In this case, it is easier to identify the reference lines L and L 'than the original of the photographed image. Further, the approximate brightness change of the photographed image can also be displayed in the converted image.

The apparatus and method for measuring straightness according to the exemplary embodiments have been described above with reference to Figs. According to the above-described embodiments, the reference lines L and L 'displayed on the object 10 can be photographed while the photographing position moves along the processing direction. Therefore, the straightness measurement speed can be faster than when the photographing position is stopped. In addition, it is possible to prevent the positions of the reference lines L and L 'from becoming unclear due to the blurring phenomenon of the image caused by the photographing position. Therefore, the accuracy of the straightness measurement can be increased.

While a number of embodiments have been described in detail above, they should be construed as examples of preferred embodiments rather than limiting the scope of the invention. Therefore, the scope of the present invention should not be limited by the described embodiments but should be determined by the technical idea described in the claims.

100: Straightness measuring device
112: light source
114: condensing optical system
130: Moving stage
135: Encoder
140: Processor
10: object
20: Chuck

Claims (14)

A method for measuring a straightness of a direction in which an object is processed,
Obtaining a photographed image of a reference line displayed on an object while changing a photographing position along a processing direction of the object; And
Measuring a straightness of the machining direction from a position of the reference line in the shot image,
Wherein the step of acquiring the captured image includes a step of measuring a straightness degree such that a line width of the reference line appearing in the captured image according to the movement of the photographing position is smaller than 1/2 of a resolution of the photographing unit acquiring the photographing image of the reference line Way. delete The method according to claim 1,
The step of acquiring the captured image includes:
Wherein the exposure time for photographing the photographed image and the speed at which the photographing position is moved satisfy Equation (1).
V * E * tan < P / M.
(V = Machining position moving speed, E = Exposure time, θ = Angle between machining direction and reference line, P = Pixel size, M = Magnification) The method according to claim 1,
The step of acquiring the captured image includes:
Wherein the magnitude of the first direction and the magnitude of the second direction of the photographed image are different from each other. 5. The method of claim 4,
The step of acquiring the captured image includes:
Wherein the photographed image is photographed in a line image. The method according to claim 1,
Wherein measuring the straightness comprises:
Converting the shot image into a binarized image based on the brightness of the shot image, and identifying the position of the reference line from the binarized image. The method according to claim 1,
Wherein the step of acquiring the shot image acquires the shot image so as to generate a pulse signal as the shooting position changes and synchronize with the pulse signal. An apparatus for measuring a straightness of a direction in which an object is processed,
A photographing unit for acquiring a photographed image of a reference line displayed on an object;
A moving stage for moving a photographing position of the photographing unit along a processing direction of the object; And
And a processor for measuring the straightness of the machining direction from the position of the reference line shown in the shot image,
Wherein the processor controls the photographing section such that a line width of the reference line appearing in the photographed image as the photographing position moves is smaller than half the resolution of the photographing section. delete 9. The method of claim 8,
The processor comprising:
Wherein the control unit controls the photographing unit and the moving stage such that a speed at which the photographing position moves and an exposure time of the photographing unit satisfy Equation (1).
V * E * tan < P / M.
(V = Machining position moving speed, E = Exposure time, θ = Angle between machining direction and reference line, P = Pixel size, M = Magnification) 9. The method of claim 8,
Wherein,
And the magnitude of the first direction and the magnitude of the second direction of the photographed image are different from each other. 12. The method of claim 11,
Wherein,
And photographs the photographed image as a line image. 9. The method of claim 8,
The processor comprising:
And converts the photographed image into a binarized image based on the brightness of the photographed image. 9. The method of claim 8,
And an encoder for generating a pulse signal as the photographing position is changed,
Wherein the photographing unit is synchronized with the pulse signal to obtain the photographed image.
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