TW201730511A - Apparatus and method of measuring straightness - Google Patents

Abstract

An apparatus for and a method of measuring straightness are provided. The method of measuring straightness includes the operation of acquiring a captured image of a reference line marked on an object while changing a location to be photographed according to a processing direction of the object and the operation of measuring straightness of the processing direction from a location of the reference line shown on the captured image.

Description

Straightness measuring device and method

The present invention relates to an apparatus and method for measuring the straightness of a processing direction of an object.

The processing for forming a mark pattern or a cut object on an object is machined and laser processed. Generally, a laser processing process is a process of processing a shape or physical properties on a surface of a workpiece by scanning a laser beam toward a surface of the workpiece.

In order to improve the processing quality of the object, it is important to accurately move the position where the mechanical pressure is applied or the irradiation position of the laser beam along the pre-processing line. In a usual processing process, the machining position can be changed by linearly moving the object or linearly moving the processing equipment by moving the platform.

However, when the above-described machining position is changed, the movement trajectory of the moving platform cannot be accurately moved along the ideal straight line due to mechanical tolerances other than vibration. The degree to which the line formed by the process is separated from the straight line is referred to as the straightness of the machine direction. In the processing of the object, it is required to measure the straightness and check the processing error.

[Question to be solved by the invention]

According to the exemplary embodiment, the accuracy of the straightness of the processing direction of the object to be measured can be improved.

[Means for solving the problem]

In one aspect, a straightness measuring method is provided, which is a method of measuring the straightness of a machining direction of an object, and the straightness measuring method includes the following steps: when the position of the shooting is changed according to the processing direction of the object, Obtaining a captured image of a reference line indicated on the object; and measuring a straightness of the machining direction according to a position of the reference line displayed on the captured image; and obtaining the photographing In the step of the image, the line width of the reference line displayed to the captured image due to the movement of the photographing position is smaller than the resolution of the photographing unit.

The imaging unit may make the line width of the reference line smaller than 1/2 of the resolution of the imaging unit.

In the step of obtaining the captured image, the exposure time of capturing the captured image and the speed of moving the shooting position satisfy Equation 1; V*E*tanθ<P/M... Equation 1 (V=machining speed of machining position) , E = exposure time, θ = angle between the machining direction and the reference line, P = pixel size, M = magnification).

In the step of obtaining the above-described captured image, the length of the first direction of the captured image is different from the length of the second direction.

In the step of obtaining the above-described captured image, the captured image is captured as a line image.

The step of measuring the straightness may include the steps of: converting the captured image into a binary image based on the brightness of the captured image; and identifying the position of the reference line based on the binary image.

The straightness measuring method may further include the step of generating a pulse signal by changing the shooting position, and obtaining the captured image by synchronizing the pulse signal in the step of obtaining the captured image.

In another aspect, a straightness measuring device for measuring a straightness of a machining direction of an object, wherein the straightness measuring device includes: an imaging unit for obtaining a reference line displayed on an object a moving platform that moves an imaging position of the imaging unit in a processing direction of the object; and a processor that measures a straightness of the processing direction based on a position of the reference line displayed on the captured image; and the processing The object rotates the object so that the line width of the reference line displayed to the captured image due to the movement of the imaging position is smaller than the resolution of the imaging unit.

The processor can control the imaging unit such that a line width of the reference line is smaller than 1/2 of a resolution of the imaging unit.

The processor can control the imaging unit and the moving platform such that the moving speed of the imaging position and the exposure time of the imaging unit satisfy Equation 1; V*E*tanθ<P/M... Equation 1 (V=Processing Position moving speed, E = exposure time, θ = angle between the machining direction and the reference line, P = pixel size, M = magnification).

The imaging unit may have a length in the first direction of the captured image different from a length in the second direction.

The imaging unit can capture the captured image as a line image.

The processor is capable of converting the captured image into a binary image based on the brightness of the captured image.

The straightness measuring device may further include an encoder that generates a pulse signal by changing the shooting position, and the imaging unit obtains the captured image by synchronizing the pulse signals.

[Effect of the invention]

According to the straightness measuring apparatus of the present embodiment, the reference line displayed on the object can be captured while the imaging position is moving in the machining direction. Therefore, unlike the case where the measurement is performed in a state where the imaging position is stationary, the straightness measurement device has a relatively high straightness measurement speed. Further, the straightness measuring device can prevent the position of the reference line from being blurred due to the image blurring phenomenon caused by the movement of the shooting position. Therefore, the photographing accuracy of the straightness measuring device can be improved.

In the following drawings, the same reference numerals are given to the same components, and the size of each component may be exaggerated in the drawing for clarity and convenience of description. On the other hand, the embodiments described below are merely examples, and various modifications can be made according to such embodiments.

The first and second terms can be used to describe various constituent elements, but the constituent elements should not be limited by the terms. The term is used only for the purpose of distinguishing one component from another component.

If not explicitly indicated in the text, the singular expression includes the plural expression. In addition, when a part is "included" to a certain component, unless otherwise stated, it means that it may include other components, and does not mean that other components are excluded.

Further, terms such as "parts" and "modules" described in the specification refer to units that process at least one function or operation.

FIG. 1 is a view exemplarily showing a laser processing process of the object 10.

Referring to Fig. 1, an object 10 can be attached to the chuck 20. The light source 112 can illuminate the object 10 with a laser beam. The position at which the light source 112 illuminates the object 10 with the laser beam can be changed by the moving platform 130. The moving platform 130 can move the chuck 20 on which the object 10 is mounted in a straight line (y-axis direction). The object 10 is moved by moving the chuck 20 by the moving platform 130, so that the laser mark pattern can be formed on the object 10 in a straight line.

In FIG. 1, the laser processing process is exemplarily shown, but the processing process applicable to the embodiment is not limited thereto. For example, the embodiments described in the present specification can also be applied to a mechanical grooving process, a cutting process, and the like.

The object 10 may include a wafer, a semiconductor wafer, or the like as an object to be photographed, and is not limited thereto. In order to accurately realize the processing of the object 10, it is necessary to make the pre-processing line of the object 10 coincide with the moving direction of the processing position of the object 10. Therefore, the direction in which the object 10 is arranged on the chuck 20 can be aligned with the machining direction.

FIG. 2 is a view exemplarily showing the surface of the object 10.

Referring to FIG. 2, the object 10 may include a plurality of semiconductor wafers 11 arranged in a checkered shape. Recognizable reference lines L, L' may be displayed on the surface of the object 10. The reference lines L, L' may be a straight line such as the pre-cut line L, or may be in the form of a line segment such as the edge L' of the semiconductor wafer 11. That is, in the captured image, the reference lines L, L' can be displayed as an image in the form of a straight line or a line segment.

In the laser processing process, a portion of the reference lines L, L' of the object 10 may be irradiated with a laser beam. When the laser beam is irradiated along the reference lines L, L', the plurality of semiconductor wafers 11 included in the object 10 can be separated into a single body. The separated semiconductor wafer 11 can be packaged in a plastic package.

In order to prevent the semiconductor wafer 11 from being damaged during the processing, it is necessary to make the moving direction (y-axis direction) of the laser beam parallel to the pre-cut line L in the reference lines L, L' of the object 10. Therefore, the reference lines L, L' of the object 10 and the processing direction (y-axis direction) of the laser beam can be made nearly parallel by adjusting the arrangement angle of the object 10.

However, even if the arrangement direction of the object 10 is adjusted with reference to the reference lines L and L', the laser beam is irradiated to a position away from the pre-cut line L. For example, the moving direction (y-axis direction) of the position at which the laser beam is irradiated due to an error in the alignment process is not completely parallel with the pre-cut line L. Also, the direction in which the mobile platform 130 moves the chuck 20 may not be completely straight. The mobile platform 130 itself may have a defect, and vibration may also occur in a direction (x-axis direction) perpendicular to the moving direction (y-axis direction) during the movement of the chuck 20 by the moving platform 130. The irradiation position of the laser beam may not completely move in a straight line as shown in FIG. 2 due to the above-mentioned equipment defects or vibrations occurring during the movement.

The difference between the actual machining direction and the ideal straight line is called the straightness of the machining direction. Under normal circumstances, the straightness may not be zero. When the straightness is too large, the processing quality is lowered, and the semiconductor wafer 11 included in the object 10 is also damaged by the laser beam.

FIG. 3 is a view schematically showing a straightness measurement device 100 of an exemplary embodiment.

Referring to Fig. 3, the straightness measuring apparatus 100 of the exemplary embodiment may include an imaging unit 110 that obtains a captured image of the reference lines L, L' displayed on the object 10, and a moving platform 130 along the processing of the object 10. The direction of movement of the imaging unit 110 is moved, and the processor 140 measures the straightness of the machining direction based on the positions of the reference lines L and L′ displayed on the captured image.

The imaging unit 110 can image the surface of the object 10 . The imaging unit 110 can obtain a captured image a plurality of times while the imaging position is changed by the movement platform 130. The photographing section 110 may transmit the obtained photographed image information to the processor 140. In FIG. 3, the imaging unit 110 and the processor 140 are shown as separate configurations, but the embodiment is not limited thereto. For example, the processor 140 may also be built in the imaging unit 110. Moreover, the processor 140 and the imaging unit 110 can share a part of the hardware resources.

The imaging unit 110 can receive light reflected from the object 10 . The imaging unit 110 may also include a light source 112 for illuminating the object 10 with light. For example, the imaging unit 110 can illuminate the object 10 with the illumination light by the light source 112 to ensure a sufficient amount of light received. The straightness measuring device 100 may further include a collecting optical system 114 provided between the imaging unit 110 and the object 10. The collecting optical system 114 can condense the light irradiated from the light source 112 to the imaging position of the imaging unit 110 to increase the amount of light received by the imaging unit 110. Also, the power consumption of the light source 112 can be reduced by the collecting optics 114.

The moving platform 130 can change the position at which the imaging unit 110 captures the object 10 . The moving platform 130 can change the imaging position of the imaging unit 110 by changing the relative position between the imaging unit 110 and the object 10 in the y-axis direction. For example, the mobile platform 130 can move the photographing position of the photographing portion 110 by moving the chuck 20 on which the object 10 is mounted. However, the embodiment is not limited to this. The moving platform 130 can change the imaging position of the imaging unit 110 by changing the position of the imaging unit 110, and can move both the imaging unit 110 and the object 10.

The processor 140 can control the imaging unit 110 and the mobile platform 130. The processor 140 can control the exposure time of the imaging section 110. Further, the time interval at which the imaging unit 110 captures an image can be controlled. For example, while the mobile platform 130 changes the shooting position at a fixed speed, the processor 140 may cause the imaging unit 110 to take an image at a fixed time interval. The processor 140 can derive the amount of change in the distance of the shooting position based on the time interval information between the time points at which the captured image is captured. The processor 140 can control whether the mobile platform 130 is operating and the speed at which the mobile platform 130 moves the shooting position.

FIG. 4 is a flowchart showing a method of measuring the straightness by the straightness measuring device 100 shown in FIG. 3.

Referring to FIG. 4, the straightness measuring method of the embodiment may include the step of obtaining a photographed image of the reference lines L, L' indicated on the object 10 when the photographing position is changed along the processing direction of the laser; The step 1120 of measuring the straightness of the machining direction based on the positions of the reference lines L and L' displayed in the captured image.

In step 1110, the imaging unit 110 can capture the surface of the object 10. The imaging unit 110 can capture the reference lines L and L′ displayed on the object 10 . The moving platform 130 can move the shooting position of the shooting section 110. The imaging unit 110 can obtain a captured image a plurality of times while the imaging position is moving in the y-axis direction. The imaging unit 110 can image the object 10 while the moving platform 130 changes the imaging position. In this case, the time at which the captured image is obtained at a plurality of shooting positions can be shortened as compared with the case where the shooting is performed in a state where the moving platform 130 is stopped.

The processor 140 can control the exposure time of the imaging unit 110 and the speed at which the mobile platform 130 moves the shooting position. The processor 140 can control the line width of the reference lines L, L' displayed to the captured image to be smaller than the resolution of the imaging unit 110 by controlling the exposure time and speed. Hereinafter, the increase in the line width of the reference lines L and L' due to the blur phenomenon of the captured image will be described.

When the machining direction is exactly parallel to the reference lines L and L' and, for example, the pre-cut line L, the line width of the reference lines L and L' does not change even if the imaging position moves in the machining direction. However, as described above, the machining direction cannot be accurately aligned with the reference lines L and L' due to the deformation of the arrangement angle of the object 10. Further, the direction in which the moving platform 130 moves the object 10 cannot be accurately aligned with the y-axis due to vibration or the like generated by the moving platform 130, and thus the machining direction is deformed from the reference lines L and L'.

FIG. 5 is a view for explaining a change in line width of the above-described reference lines L and L'.

Referring to Figure 5, the machine direction k and the reference lines L, L' may not be completely parallel. The angle θ between the machining direction k and the reference lines L, L' may vary depending on the arrangement angle of the object 10 and the magnitude of vibration occurring during the operation of the moving platform 130. For example, the angle θ can be defined as the angle between the machining direction k and the pre-cut line L. When the object 10 is imaged while changing the imaging position in the processing direction k, the positions of the reference lines L and L' are changed during the exposure period of the imaging unit 110. Therefore, the effect of blurring the reference lines L, L' in the captured image occurs due to the movement of the shooting position.

FIG. 6 is a view showing changes in the positions of the reference lines L and L' due to the movement of the imaging position in the machining direction k during the exposure period.

Referring to Fig. 6, the machine direction k and the reference lines L, L' may not be parallel to each other. The imaging unit 110 can image the object 10 during a specific exposure period. During the exposure period, the relative position of the object 10 and the imaging unit 110 is changed, and the imaging position is moved by the distance d in the machining direction k. While the shooting position is moving by the distance d, the position of the reference lines L, L' can be moved by a distance w in a direction perpendicular to the machining direction k. Therefore, the reference lines L and L' are blurably captured in the captured image, and the line widths of the reference lines L and L' are increased.

FIG. 7 is a view showing an increase in the line width of the reference lines L and L' in the captured image.

Referring to Fig. 7, the line widths of the reference lines L, L' increase due to the effect of blurring of the captured image of the imaging unit 110. The reference lines L, L' move in a direction perpendicular to the machining direction k due to a change in the imaging position during the exposure of the imaging unit 110. Therefore, the positions of the reference lines L, L' are not accurately specified in the captured image, and the line widths of the reference lines L, L' are increased.

The line width of the reference lines L, L' may depend on the angle θ between the machining direction k and the reference lines L, L', the exposure time of the imaging unit 120, and the moving speed of the shooting position. For example, the larger the exposure time of the imaging unit 120 and the larger the moving speed of the imaging position, the larger the line width of the reference lines L and L'.

When the line widths of the reference lines L and L' become too large, the accurate positions of the reference lines L and L' cannot be easily determined in the captured image. When the position error of the reference lines L and L' in the captured image becomes large, the error of the value of the straightness of the machining direction k read from the captured image also increases.

In the straightness measurement method of an embodiment, in step 1110, the line width of the reference line displayed to the captured image by the movement of the imaging position is smaller than the resolution of the imaging unit 110. Here, the resolution of the imaging unit 110 can be determined based on the pixel size and magnification of the imaging unit 110. As an example, the resolution of the imaging unit 110 can be determined by Equation 1.

[Equation 1]

In Equation 1, r is the resolution of the imaging unit 110. Also, P, as the size of the pixel, may refer to the size of the length or width of the pixel. In addition, M means the magnification of the imaging unit 110. In the case of a camera device used in a laser processing process, the above resolution may be approximately 0.2 μm to 0.3 μm. However, the above numerical values are merely examples and are not limitative of the embodiments.

The processor 140 can make the line width of the reference lines L, L' displayed to the captured image smaller than the resolution r of the imaging unit 110 by adjusting the exposure time of the imaging unit 110 and the speed at which the moving platform 130 moves the imaging position. When the line width of the reference lines L and L' is smaller than the resolution r of the imaging unit 110, the error of the position of the reference lines L and L' can be reduced in the captured image. Further, if the error of the position of the reference lines L and L' is reduced, the measurement error of the straightness can be reduced.

By way of example, the processor 140 can make the line width of the reference lines L, L′ displayed to the captured image smaller than the resolution of the imaging unit 110 by adjusting the exposure time of the imaging unit 110 and the speed at which the mobile platform 130 moves the imaging position. Half of the degree r. When the line width of the reference lines L and L' is smaller than half of the resolution r of the imaging unit 110, the reference lines L and L' can be displayed to only one pixel in the captured image. Therefore, the error caused by the image blurring effect caused by the dynamic shooting can be almost eliminated.

The processor 140 can satisfy the exposure time E of the imaging unit 110 and the speed V at which the moving platform 130 moves the shooting position to satisfy Equation 2.

[Equation 2]

In Equation 2, V = machining position moving speed, E = exposure time, θ = angle between the machining direction k and the reference lines L, L', P = pixel size, M = magnification.

Referring to Equation 2, V*E may correspond to the distance d shown in FIG. 6. That is, during the exposure time E, the distance d in which the photographing position moves in the processing direction k can be the same as the product of the exposure time E and the moving speed V of the photographing position. Further, V*E*tanθ may correspond to the distance w shown in FIG. 6. That is, during the exposure time E, the distance w between the positions of the reference lines L, L' moving in the direction perpendicular to the machining direction k can be moved by the distance d between the shooting position and the machining direction k and the reference line L, L' The angle θ is determined. According to Equation 2, during the exposure time E, the distance w of the position of the reference lines L, L' moving in the direction perpendicular to the machining direction k may be smaller than the resolution of the imaging unit 110 (r = P / M). The distance w can be almost the same as the line width of the reference lines L, L' formed by the blurring effect of the image. Therefore, the line width of the reference lines L, L' can become smaller than the resolution of the imaging section 110.

In a typical laser processing process, tan θ may have a value in the range of approximately 0 to 10 ^-4 . Therefore, when the resolution P/M has a value of approximately 0.2 μm to 0.3 μm, the velocity V and the exposure time E can substantially satisfy V*E ≤ 100 μm. However, if the speed V of the moving photographing position is too small, it is difficult to measure the straightness at a high speed, and the exposure time E can substantially satisfy E < 2 ms. The above numerical values are merely examples and are not limitative of the embodiments.

FIG. 8 is a view showing an example of a captured image captured by the imaging unit 110.

Referring to Fig. 8, reference lines L, L' can be displayed in the captured image of the imaging unit 110. The line width of the reference lines L, L' may be smaller than the resolution of the imaging unit 110 in the x-axis direction. Therefore, the x-axis position of the reference lines L, L' can be defined by one pixel position in the captured image.

The photographing section 110 can obtain a photographed image as shown in FIG. 8 every time the photographing position changes. The straightness of the machining direction can be determined in accordance with the degree of shifting of the position of the reference lines L and L' in the x-axis direction among the plurality of captured images. That is, it is important in the captured image whether or not the reference lines L and L' are shifted in the x-axis direction, so that the necessity of obtaining the entire image of the object 10 in the y-axis direction is small. Therefore, the size of the captured image captured by the imaging unit 110 in the x-axis direction and the size in the y-axis direction are different.

For example, the length of the y-axis direction of the captured image (the direction in which the photographing position is moved by moving the stage 130) may be smaller than the length of the captured image in the x-axis direction. The imaging unit 110 can capture a partial frame instead of the entire frame of the object 10 . For example, the imaging unit 110 can capture only a part of the frame of the object 10 in the direction in which the position of the position is moved by the moving platform 130 (y-axis direction), and the entire frame can be captured in the x-axis direction. The above is merely an example and is not intended to limit the embodiments.

When the imaging unit 110 captures only a part of the frame in the y-axis direction, the number of times the imaging unit 110 can capture an image per hour increases. Therefore, the exposure time E of the imaging section 110 can be easily adjusted to be small. Moreover, the time interval for changing the position of the reference lines L, L' is shorter because more images are obtained per unit time. If the imaging unit 110 obtains more captured images at shorter time intervals, the accuracy of measuring the straightness of the machining direction can be further improved.

As an example, the imaging unit 110 can also capture a line image. That is, only one pixel can be provided in the y-axis direction in the captured image. When the imaging unit 110 captures a line image, the configuration of the imaging unit 110 is simplified because only one pixel is provided in the y-axis direction. Further, since the light receiving elements included in the imaging unit 110 are easily arranged in the y-axis direction, the light receiving area per unit pixel is widened. Since the light receiving area per unit pixel of the imaging unit 110 is widened, the sharpness of the captured image can be improved.

Referring again to FIG. 4, in step 1120, the processor 140 may determine the straightness of the machining direction k based on the positions of the reference lines L, L' displayed on the plurality of captured images. The processor 140 may receive a plurality of captured images from the photographing section 110. A plurality of captured images may be obtained by separately shooting different shooting positions. While the relative position between the light source 112 and the object 10 is changed by the movement platform 130, the imaging unit 110 can obtain a captured image of the object 10 and transmit it to the processor 140. The processor 140 can measure the straightness of the machining direction k based on the positions of the reference lines L, L' respectively displayed on the plurality of captured images.

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

Referring to FIG. 9, the processor 140 may receive a plurality of captured images from the photographing section 110. For example, the processor 140 may identify the positions of the reference lines L, L' in the first image a, the second image b, and the third image c, respectively. Referring to Fig. 9, in the first image a and the second image b, the positions of the reference lines L, L' are hardly changed, and in the third image c, the positions of the reference lines L, L' are movable by Δx. The processor 140 can capture the position offset amount Δx in the x-axis direction of the reference lines L, L′ and the moving platform 130 during the period of capturing the first image a, the second image b, and the third image c. The straightness of the machining direction k is obtained by the ratio of the distance of the position moving in the y-axis direction.

In order to accurately know the straightness, the processor 140 not only needs to refer to the positional shift amount Δx of the line L, L′ in the x-axis direction, but also needs to capture the first image a, the second image b, and the third image. The distance information of the position where c is moved along the y-axis during the period of c.

In order for the processor 140 to easily obtain the moving distance information of the shooting position, the photographing unit 110 can photograph the object 10 every time the shooting position is changed by the moving platform 130 by a certain distance. For example, the imaging unit 110 can image the object 10 by synchronizing the pulse signals generated when the moving platform 130 moves the object 10 or the imaging unit 110 by a fixed distance.

Referring again to FIG. 3, the straightness determining apparatus 100 of the embodiment may further include an encoder 135 that generates a pulse signal each time the shooting position is changed by a specific distance. Encoder 135 can be coupled to mobile platform 130 to sense mechanical movement of mobile platform 130. The encoder 135 can sense the distance that the mobile platform 130 moves the light source 112 or the object 10. The encoder 135 can generate a pulse signal each time the shooting position of the imaging unit 110 is moved by a certain interval by the mobile platform 130. The pulse signal generated in the encoder 135 can be transmitted to the imaging unit 110.

The operation of the imaging unit 110 can be synchronized by the pulse signal of the encoder 135. For example, when the imaging unit 110 receives the pulse signal, the imaging unit 110 can image the object 10 during the exposure time E. The imaging unit 110 is synchronized by the pulse signal of the encoder 135, so that the captured image can be obtained every time the shooting position is changed by a fixed distance in the y-axis direction. In addition, the processor 140 may derive the amount of change in the shooting position according to the number of captured images during the shooting of the captured image.

In FIGS. 8 and 9, the reference lines L, L' can be relatively easily recognized in the captured image. However, depending on the quality of the captured image, there may be cases where it is difficult to recognize the reference lines L, L'.

Fig. 10 is a view showing an example of a captured image.

Referring to Fig. 10, when the brightness of the captured image changes little, it is difficult to recognize the reference lines L, L'. If it is difficult for the processor 140 to recognize the reference lines L and L', it is difficult to measure the straightness based on the positional changes of the reference lines L and L'.

In order to solve the problem shown in FIG. 10, the processor 140 can binary the captured image received from the imaging unit 110 based on the luminance. The processor 140 may be divided into a region where the luminance is higher than a specific reference value and a region where it is not. The processor 140 may process an area in which the brightness is higher than the reference value into white in the captured image, and process an area in which the brightness is lower than the reference value into black.

Fig. 11 is a view showing a binary image obtained by folding the captured image shown in Fig. 10.

Referring to FIG. 11, the processor 140 may generate a binary image obtained by binarizing the captured image shown in FIG. 10 on the basis of luminance. In the binary image, it is easy to distinguish between a region where the luminance is higher than the reference value and a region where the luminance is lower than the reference value. Therefore, the positions of the reference lines L, L' can be easily recognized in the binary image.

In FIG. 11, the processor 140 binars the captured image based on the luminance, but the embodiment is not limited thereto. The processor 140 may also display the brightness of the captured image discontinuously in accordance with the predetermined brightness intervals. For example, the processor 140 may also display a region having a luminance value within the first range into a first luminance and display the region having the luminance value in the second range into a second luminance in the captured image. Display is performed by unifying the area having the luminance value in the third range into the third brightness. That is, the processor 140 may also display the captured image as n (n is an arbitrary natural number) luminance value.

FIG. 12 is an image obtained by converting the captured image shown in FIG. 10 into a predetermined plurality of luminance values.

Referring to FIG. 12, a captured image may be displayed in a plurality of luminance values. In this case, the reference lines L, L' can be identified more easily than the original of the captured image. Further, a substantial change in luminance of the captured image may be displayed in the converted image.

The straightness measuring apparatus and method of the exemplary embodiment have been described above with reference to Figs. 1 to 12 . According to the above embodiment, the reference lines L, L' displayed on the object 10 can be captured while the imaging position is moved in the machining direction. Therefore, the straightness measurement speed is faster than the case where the measurement is performed while the shooting position is stationary. Further, it is possible to prevent the position of the reference lines L and L' from being unclear due to the image blurring phenomenon caused by the movement of the shooting position. Therefore, the accuracy of measuring the straightness can be improved.

In the above description, various matters are specifically described, but these matters are not intended to limit the scope of the invention, and should be construed as an example of a preferred embodiment. Therefore, the scope of the invention should not be limited by the illustrated embodiments, but should be defined by the technical idea recited in the claims.

10‧‧‧ objects
11‧‧‧Semiconductor wafer
20‧‧‧ chuck
100‧‧‧straightness measuring device
110, 120‧‧ ‧Photography Department
112‧‧‧Light source
114‧‧‧Concentrating optical system
130‧‧‧Mobile platform
135‧‧‧Encoder
140‧‧‧ processor
1110, 1120‧‧‧ steps
d, w‧‧‧ distance
k‧‧‧Processing direction
L, L'‧‧‧ reference line θ‧‧‧An angle between the machining direction and the reference line Δx‧‧‧ position offset

FIG. 1 is a view exemplarily showing a laser processing process of an object. FIG. 2 is a view exemplarily showing the surface of an object. Fig. 3 is a view schematically showing a straightness measuring device of an exemplary embodiment. 4 is a flow chart showing a method of measuring the straightness using the straightness measuring device shown in FIG. 3. Fig. 5 is a view for explaining a change in line width of the above reference line. FIG. 6 is a view showing a change in the position of the reference line when the imaging position moves in the machining direction during the exposure period. FIG. 7 is a view showing an increase in line width of a reference line in a captured image. 8 is a view showing an example of a captured image captured by an imaging unit. FIG. 9 is a view exemplarily showing a plurality of captured images received by the array processor. Fig. 10 is a view showing an example of a captured image. Fig. 11 is a view showing a binary image obtained by folding the captured image shown in Fig. 10. FIG. 12 is an image obtained by converting the captured image shown in FIG. 10 into a predetermined plurality of luminance values.

10‧‧‧ objects

20‧‧‧ chuck

100‧‧‧straightness measuring device

110‧‧‧Photography Department

112‧‧‧Light source

114‧‧‧Concentrating optical system

130‧‧‧Mobile platform

135‧‧‧Encoder

140‧‧‧ processor

Claims (14)

A straightness measuring method for measuring a straightness of a machining direction of an object, comprising: obtaining a reference line marked on the object when a position of the image is changed according to the machining direction of the object And determining a straightness of the machining direction according to a position of the reference line displayed on the captured image, and displaying the captured image due to movement of the shooting position in obtaining the captured image The line width of the reference line of the image is smaller than the resolution of the imaging unit. The straightness measuring method according to claim 1, wherein the imaging unit makes a line width of the reference line smaller than 1/2 of a resolution of the imaging unit. The straightness measurement method according to claim 1, wherein in obtaining the captured image, an exposure time of capturing the captured image and a moving speed of the shooting position satisfy Equation 1: V*E *tan θ < P / M ... Equation 1, where V is the machining position moving speed, E is the exposure time, θ is the angle between the machining direction and the reference line, P is the pixel size, and M is the magnification. The straightness measurement method according to claim 1, wherein in the obtained captured image, the first direction length of the captured image is different from the second direction length. The straightness measuring method according to the fourth aspect of the invention, wherein the captured image is taken as a line image in obtaining the captured image. The straightness measuring method according to claim 1, wherein the measuring the straightness comprises: converting the captured image into a binary image based on a brightness of the captured image; The binary image identifies the location of the reference line. The straightness measurement method according to claim 1, further comprising: generating a pulse signal by changing the photographing position, wherein the pulse signal is obtained by obtaining the photographed image The captured image is obtained by synchronizing. A straightness measuring device for measuring a straightness of a machining direction of an object, comprising: an image capturing portion for obtaining a captured image of a reference line displayed on the object; a moving platform, processing along the object a direction of moving the imaging position of the imaging unit; and a processor determining a straightness of the machining direction according to a position of the reference line displayed on the captured image, and the processor is caused by the shooting position The imaging unit is controlled such that the line width of the reference line displayed to the captured image is smaller than the resolution of the imaging unit. The straightness measuring apparatus according to claim 8, wherein the processor controls the imaging unit such that a line width of the reference line is smaller than 1/2 of a resolution of the imaging unit. The straightness measuring apparatus according to claim 8, wherein the processor controls the photographing unit and the photographing manner in such a manner that the moving speed of the photographing position and the exposure time of the photographing portion satisfy Equation 1 Mobile platform: V*E*tanθ<P/M... Equation 1, where V is the machining position moving speed, E is the exposure time, θ is the angle between the machining direction and the reference line, P is the pixel size, and M is the magnification . The straightness measurement device according to claim 8, wherein the imaging unit makes the first direction length of the captured image different from the second direction length. The straightness measurement device according to claim 11, wherein the imaging unit captures the captured image as a line image. The straightness measuring apparatus according to claim 9, wherein the processor converts the captured image into a binary image based on a brightness of the captured image. The straightness measuring apparatus according to claim 8, further comprising an encoder that generates a pulse signal due to a change in the photographing position, wherein the pulse signal is synchronized by the pulse signal The photographing unit obtains the photographed image.