JP2013072825A - Image acquisition device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily change a detection angle when acquiring an image of a thin film pattern formed on a sheet-like substrate.SOLUTION: An image acquisition device 1 comprises a drum 11 centering a central axis K, and by rotation of the drum 11, a web 9 is conveyed along an outside surface 111. The image acquisition device 1 further comprises a light irradiation part 21 for irradiating an imaging region 90, being linear and in parallel with the central axis K, with light and a light receiving part 23 where light from the imaging region 90 is received by a line sensor. The light irradiation part 21 and the light receiving part 23 are moved by a movement mechanism 4 in two directions that are perpendicular to the central axis K and that cross each other. By controlling the movement mechanism 4, a detection angle θ2, formed between an optical axis J2 of the light receiving part 23 and a normal line N of the web 9, is changed, and a focus position P conjugated with a light receiving surface of the line sensor on the optical axis J2 is arranged on a surface of a thin film pattern. Thus, the detection angle θ2 can be easily changed by only the movement mechanism 4 for moving the light receiving part 23 in the two directions.

Description

  The present invention relates to an image acquisition device that acquires an image of a thin film pattern formed on a sheet-like substrate.

  Conventionally, in various fields, a pattern formed on a film-like or plate-like substrate has been inspected. For example, in the pattern inspection apparatus disclosed in Patent Document 1, a wiring pattern formed on a resin film is inspected. In the pattern inspection apparatus, an image with good contrast can be obtained by using an LED (Light Emitting Diode) that emits only light having a wavelength of 500 nm or more as a light source.

  In the film thickness measuring device disclosed in Patent Document 2, light is irradiated from a semiconductor laser to a transparent polyester film, and the intensity of specular reflection light is detected by a silicon photodiode. The semiconductor laser and the silicon photodiode are moved within the range of 0 ° to 90 ° by the stepping motor, and the light incident angle is changed.

JP 2006-112845 A JP 2004-101505 A

  By the way, in recent years, touch panels are provided in various electronic devices. In the manufacture of such a touch panel, a transparent pattern such as a transparent electrode is formed on a sheet-like substrate formed of resin. When visual inspection of a transparent pattern on a substrate is performed, for example, an image of the pattern is obtained by irradiating light from the light irradiation unit to the imaging region on the substrate and receiving reflected light at the light receiving unit. The In this case, it is conceivable to obtain a high-contrast image by changing the detection angle formed by the optical axis from the imaging region to the light receiving unit and the normal line of the base material to change the interference state of the received light. It is done. When the detection angle is changed by rotating the light receiving unit, a mechanism for accurately rotating the light receiving unit is required, but such a rotating mechanism is not easy to design and manufacture. Therefore, a technique for easily changing the detection angle without rotating the light receiving unit is required.

  The present invention has been made in view of the above problems, and an object of the present invention is to easily change the detection angle when acquiring an image of a thin film pattern formed on a sheet-like substrate.

  The invention according to claim 1 is an image acquisition device that acquires an image of a thin film pattern formed on a sheet-like substrate, and has an outer surface that is a cylindrical surface centered on a predetermined central axis. A drum that conveys the substrate along the outer surface by rotating about the central axis, and the substrate that holds light of a wavelength having transparency to the thin film pattern. A light emitting unit that emits light toward a linear imaging region parallel to the central axis, a light sensor that includes a line sensor, and an optical system that guides light from the imaging region to the line sensor; A moving mechanism that moves the light irradiation unit and the light receiving unit in two directions perpendicular to the central axis and intersecting each other, and by controlling the moving mechanism, the optical axis of the optical system and the normal of the base material If you change the detection angle between In, and a control section for arranging the light receiving surface conjugate with the position of the line sensor on the thin film pattern on said optical axis.

  Invention of Claim 2 is an image acquisition apparatus of Claim 1, Comprising: The predetermined | prescribed angular range centering on the axis | shaft which the said light irradiation part passes along the said conjugate position parallel to the said imaging region And irradiates the imaging region with the light, and on the surface perpendicular to the axis, an angular position inclined from the normal to the opposite side of the optical axis by the detection angle about the axis Is included in the predetermined angle range.

  A third aspect of the present invention is the image acquisition device according to the first or second aspect, wherein the outer surface of the drum is a correction table that indicates a shake amount in each circumferential portion centering on the central axis on the outer surface. Is further stored, and the control unit controls the moving mechanism using the correction table in synchronization with the rotation of the drum.

  According to the present invention, the detection angle can be easily changed. Further, in the invention of claim 2, the control of the image acquisition device can be simplified, and in the invention of claim 3, the position conjugate with the light receiving surface of the line sensor can be always arranged on the thin film pattern with high accuracy. it can.

It is a figure which shows schematic structure of an image acquisition apparatus. It is a figure which shows an imaging unit. It is a figure for demonstrating the change operation | movement of a detection angle. It is a figure for demonstrating the change operation | movement of a detection angle. It is a figure which shows the example of a profile. It is a block diagram which shows the function structure of an image acquisition apparatus. It is a figure which shows the flow of operation | movement of an image acquisition apparatus. It is a figure which shows the other example of an imaging unit.

  FIG. 1 is a front view showing a schematic configuration of an image acquisition apparatus 1 according to an embodiment of the present invention. The image acquisition device 1 acquires a pattern image that is an image of a multilayer thin film pattern formed on a sheet-like substrate, and executes an inspection of the thin film pattern based on the pattern image. In FIG. 1, the substrate is a web of resin film, that is, a continuous sheet. The thin film pattern is, for example, a transparent electrode film. In the present embodiment, the base material and the thin film pattern are covered with the transparent film. In practice, other layers such as an antireflection film are also provided on the substrate.

  In the following description, the thin film pattern is simply referred to as “pattern”, and the base material and the film on the base material are collectively referred to as “web 9” or “inspection object”. The web 9 is used for manufacturing, for example, a capacitive touch panel. Since most of the inspection object (web 9) is a base material, the handling of the inspection object and the like are described without strictly distinguishing between the inspection object and the base material.

  The image acquisition device 1 includes a drum 11, an imaging unit 2, a moving mechanism 4, and a computer (not shown). The drum 11 has an outer surface 111 that is a cylindrical surface centered on a predetermined central axis K parallel to the Y direction in FIG. 1, and a motor 112 is connected to the drum 11 via a speed reduction mechanism. The image acquisition apparatus 1 further includes two rollers 121 that are long in the Y direction, and the two rollers 121 are below the drum 11, front and rear ((+ X) side) and (−X) of the drum 11 in the X direction perpendicular to the Y direction. ) Side). The web 9 is placed on the (−X) side roller 121, the drum 11, and the (+ X) side roller 121 in this order.

  By driving the motor 112, the drum 11 rotates about the central axis K in the clockwise direction in FIG. 1, so that the web 9 is conveyed along the outer surface 111. That is, each part of the web 9 moves in order through the (−X) side roller 121, the drum 11, and the (+ X) side roller 121. The drum 11 is provided with an encoder 113 (see FIG. 6 described later) for detecting a rotation angle. In the moving direction of the web 9, a supply unit that supports the web 9 before inspection as a roll is provided on the upstream side of the (−X) side roller 121, and the inspection is provided on the downstream side of the (+ X) side roller 121. A collection unit for supporting the subsequent web 9 as a roll is provided.

  The moving mechanism 4 includes an X-direction moving unit 41 attached to the top plate 10 of the image acquisition device 1 and a Z-direction moving unit 42 fixed to the moving body of the X-direction moving unit 41, and the Z-direction moving unit 42. The imaging unit 2 is fixed to the moving body. The X direction moving unit 41 includes a motor, a ball screw, a guide rail, and the like, and the Z direction moving unit 42 moves in the X direction by driving the motor. Similarly, the Z-direction moving unit 42 includes a motor, a ball screw, a guide rail, and the like, and the imaging unit 2 moves in the Z direction perpendicular to the X direction and the Y direction by driving the motor. Thus, the moving mechanism 4 is a mechanism that moves the imaging unit 2 in two directions perpendicular to the central axis K and intersecting each other (the X direction and the Z direction orthogonal to each other in FIG. 1).

  FIG. 2 is a diagram illustrating the imaging unit 2. In FIG. 2, only the light irradiation unit 21 is shown in a cross section in a plane including the optical axis J <b> 2 of the light receiving unit 23. The imaging unit 2 includes a light irradiation unit 21 that emits light toward a linear (linear shape extending in the Y direction) imaging region 90 on the web 9 held by the drum 11, and reflected light from the imaging region 90. And a light receiving unit 23 for receiving light. The light receiving unit 23 includes a line sensor 231 in which a plurality of light receiving elements are arranged linearly (one-dimensionally), and an optical system 232 that guides light from the imaging region 90 to the line sensor 231. The optical system 232 is provided inside the lens barrel 233. In FIG. 2, a position optically conjugate with the light receiving surface of the line sensor 231 (hereinafter referred to as “focus position”) on the optical axis J2 of the optical system 232 parallel to the Z direction is indicated by a point P.

  The light irradiation unit 21 emits light having a wavelength that is transparent to the pattern. The light is applied at least to the linear imaging region 90 parallel to the central axis K of the drum 11. Specifically, in the light irradiation unit 21, an arcuate support unit centered on an axis (virtual axis, hereinafter referred to as “virtual axis”) that is parallel to the imaging region 90 and passes through the focus position P. 210 is provided, and the support unit 210 is fixed to the lens barrel 233 of the light receiving unit 23. A plurality of LEDs 211 are arranged on the support unit 210, and light from the plurality of LEDs 211 is made uniform through the diffusion plate 212 and irradiated onto the imaging region 90. As described above, the light irradiation unit 21 in FIG. 2 emits light toward the imaging region 90 in the predetermined angle range α around the virtual axis.

  Next, the detection angle changing operation in the imaging unit 2 will be described. The detection angle is an angle θ2 formed by the optical axis J2 (of the optical system 232) of the light receiving unit 23 in FIG. 1 and the normal line N of the web 9 in the imaging region 90. In the image acquisition device 1, the outer surface 111 and the web 9 come into contact with each other in the upper half of the circumference of the drum 11, that is, in the range where the inclination angle of the normal line of the outer surface 111 with respect to the Z direction is 0 ° to 90 °. Further, the optical axis J2 of the light receiving unit 23 is parallel to the Z direction. Therefore, depending on the position of the imaging region 90 on the region of the web 9 that contacts the drum 11 (more precisely, the angular position about the central axis K), the normal N of the web 9 and the optical axis J2 at that position. The detection angle θ2 formed by the above changes within a range of 0 ° to 90 °. In the following description, the normal N of the web 9 in the imaging region 90 is simply referred to as “the normal N of the web 9”.

  The position of the imaging unit 2 when the focus position P of the light receiving unit 23 is arranged on the thin film pattern (front surface) of the web 9 located at the apex (most (+ Z) side portion) of the drum 11 (FIGS. 3 and 4). For example, when the detection angle θ2 is φa (where 0 ° <φa <90 °), the reference position is the position of the imaging unit 2 indicated by a two-dot chain line in FIG. The movement amount DX in the X direction of the imaging unit 2 from the reference position is (sin φa) times the radius R of the drum 11 (that is, Rsin φa), and the movement amount DZ in the Z direction is (R−R cos φa). As a result, the detection angle θ2 in the imaging unit 2 becomes φa, and the focus position P is substantially arranged on the thin film pattern of the web 9 (that is, focus adjustment is performed).

  Similarly, when the detection angle θ2 is set to φb larger than φa (where φa <φb <90 °), the movement amount DX in the X direction of the imaging unit 2 from the reference position is as shown in FIG. (Rsinφb), and the movement amount DZ in the Z direction is (R-Rcosφb). As a result, the detection angle θ2 in the imaging unit 2 becomes φb, and the focus position P is arranged substantially on the thin film pattern of the web 9. As described above, in the image acquisition device 1, the operation of changing the detection angle θ <b> 2 and the focus adjustment in the imaging unit 2 are realized only by moving the imaging unit 2 in the X direction and the Z direction by the moving mechanism 4. The reference position is for simplifying the description of the amount of movement of the imaging unit 2 in the X direction and the Z direction when the detection angle θ2 is changed. The imaging unit 2 is used as a reference when the detection angle θ2 is changed. There is no need to return to position.

  In the imaging unit 2 having the light irradiation unit 21 in FIG. 2, the optical axis from the normal line N of the web 9 on the plane perpendicular to the virtual axis (that is, the axis parallel to the imaging region 90 and passing through the focus position P). In the state where an angular position (indicated by a one-dot chain line denoted by reference symbol A1 in FIG. 2) inclined by the detection angle θ2 around the virtual axis on the opposite side to J2 is included in the angular range α. An image (line image) is acquired. When attention is focused on the light incident on the light receiving unit 23 from the imaging region 90, it can be considered that the optical axis from the light irradiation unit 21 to the imaging region 90 is arranged at the angular position. When the angle formed by the normal line N of 9 is called an irradiation angle, the irradiation angle and the detection angle are equal.

  Next, the principle of image acquisition in the image acquisition device 1 will be described. FIG. 5 is a diagram illustrating a profile indicating the relationship between the detection angle and the contrast. A solid line 811 shows the relationship between the detection angle and the contrast when a 900 nm thick transparent film is formed on a 30 nm thick transparent electrode pattern. In the background, it is assumed that only a transparent film having a thickness of 900 nm exists. The wavelength of irradiation light is 570 nm.

  Here, the contrast refers to the intensity of light incident on the light receiving unit 23 (line sensor 231 thereof) when a multilayer film including a pattern is present on the substrate, and the pattern is removed from the multilayer film on the substrate. This is a ratio to the intensity of light incident on the light receiving unit 23 when only the film is present. In other words, the contrast is the lightness ratio between the pattern and the background (= (lightness of the pattern area) / (lightness of the background area)). The brightness corresponds to the reflectance at that wavelength, and the brightness ratio is also the reflectance ratio. For example, the film thickness of each layer in the region where the pattern exists on the web 9 is obtained by an external film thickness meter, and then the film thickness of each layer in the background which is the region around the pattern is obtained. The profile can be obtained by calculation based on the layer structure and the film thickness of each layer. As will be described later, in the present embodiment, a similar profile is acquired by another method. Of course, other values such as a difference in brightness and reflectance may be used as the contrast.

  In FIG. 5, normally, a good pattern image can be acquired when the contrast is 0.5 or less or 2 or more. In the case of the solid line 811, an appropriate pattern image is acquired when the detection angle is approximately 0 ° to 28 °, or 40 ° to 45 °. However, 45 ° is only a formal upper limit in FIG. If the contrast is 0.77 or less or 1.3 or more, pattern inspection is possible depending on conditions. Preferably, the contrast is 0.67 or less or 1.5 or more. Further, “high contrast” means that the contrast is good, and means that the light and dark can be clearly distinguished. High contrast does not necessarily mean that the contrast value is large.

  A broken line 812 in FIG. 5 shows the relationship between the detection angle and the contrast when a transparent film having a thickness of 960 nm is formed on a transparent electrode pattern having a thickness of 30 nm. In the background, it is assumed that only a transparent film having a thickness of 960 nm exists. An alternate long and short dash line 813 indicates a relationship between a detection angle and contrast when a transparent film having a thickness of 1000 nm is formed on a transparent electrode pattern having a thickness of 30 nm. In the background, it is assumed that only a transparent film having a thickness of 1000 nm exists. The wavelength of irradiation light is 570 nm. As shown by the curves 811 to 813, it can be seen that the detection angle at which a pattern image with high contrast is acquired greatly changes as the thickness of the transparent film changes.

  That is, when the detection angle is changed, the optical path length of the light passing through each transparent layer (light incident on the light receiving unit 23) is changed to change the interference state of the light, and thereby high contrast is obtained at a specific detection angle. Even if it cannot be obtained, it is possible to obtain high contrast by changing the detection angle without changing the wavelength. In other words, by changing the detection angle, image acquisition equivalent to acquiring a pattern image by selecting a wavelength from a number of wavelengths using a white light source and a number of filters is realized.

  FIG. 6 is a block diagram illustrating a functional configuration of the image acquisition apparatus 1. The configuration surrounded by a broken line is the configuration shown in FIG. 1 except for the encoder 113, and the other configuration is realized by the computer described above. The image acquisition device 1 includes a profile acquisition unit 31 to which an output from the light receiving unit 23 is input, an angle determination unit 32 to which a profile obtained by the profile acquisition unit 31 is input, an overall control unit 30 that controls the whole, and correction. A storage unit 33 that stores the table 331 and an inspection unit 36 that performs an inspection described later are provided. Here, the correction table 331 indicates the amount of shake at each part in the circumferential direction around the central axis K on the outer surface 111 of the drum 11. The shake amount is a value having reproducibility due to the eccentricity of the drum 11, and is obtained by measuring the radial displacement of each part of the outer surface 111 in the circumferential direction using a displacement sensor, for example. .

  FIG. 7 is a flowchart of the operation of the image acquisition device 1. In the image acquisition device 1, first, a profile indicating the relationship between the detection angle and the contrast is acquired (step S11). Specifically, the line image of the imaging region 90 is repeatedly acquired by the line sensor 231 of the light receiving unit 23 while controlling the moving mechanism 4 of FIG. At this time, the drum 11 moves the web 9 as necessary so that a pattern and a background exist in the imaging region 90, and the profile acquisition unit 31 acquires a pattern every time a line image is acquired by the line sensor 231. The ratio of the light intensity from the above area to the light intensity from the background area is obtained as the contrast. The detection angle is changed from a preset minimum angle to a maximum angle, thereby obtaining a profile.

  The angle determination unit 32 determines an angle (hereinafter referred to as “set angle”) for setting a detection angle based on the acquired profile (step S12). In determining the set angle, preferably, the angle at which the contrast is highest is selected. The set angle is input to the overall control unit 30, and the overall control unit 30 controls the moving mechanism 4, that is, moves the imaging unit 2 so that the imaging region 90 is positioned at the angular position of the drum 11 corresponding to the set angle. As a result, the detected angle becomes the set angle (step S13).

  When the above preparatory work is completed, emission of light from the light irradiation unit 21 and driving of the motor 112 are started, and conveyance of the web 9 by the drum 11 is started (step S14). In the light receiving unit 23, the line image of the linear imaging region 90 is repeatedly acquired at high speed. At this time, a signal from the encoder 113 is input to the overall control unit 30, and the moving mechanism 4 is controlled based on the correction table 331 in synchronization with the rotation angle of the drum 11, whereby each of the outer surfaces 111 of the drum 11 is controlled. The imaging unit 2 slightly moves according to the shake amount in the part. Thereby, the focus position P of the light receiving unit 23 is always arranged on the thin film pattern of the web 9. Through the above operation, the inspection unit 36 acquires (that is, stores) data of a two-dimensional pattern image indicating a thin film pattern (step S15).

  The inspection unit 36 stores reference image data serving as a reference, and the presence or absence of a defect is determined by comparing the pattern image data with the reference image data (step S16). Actually, steps S15 and S16 are repeatedly executed every time the web 9 is transported by a certain distance. When all the inspections for the web 9 are completed, the light irradiation and the transport of the web 9 are stopped, and the inspection is performed. The process ends (step S17). In the inspection unit 36, if the amount of light incident on the light receiving unit 23 changes depending on the detection angle, the pattern image data may be corrected according to the set angle. Further, the inspection may be performed by normalizing the pattern image and the reference image by a predetermined method and comparing both the normalized images. Of course, the inspection of the pattern image may be performed by a method other than the comparison with the reference image.

  As described above, in the image acquisition device 1, the drum 11 that transports the web 9 along the outer surface 111, and the imaging unit 2 in two directions perpendicular to the central axis K of the drum 11 and intersecting each other. A moving mechanism 4 that moves is provided, and by controlling the moving mechanism 4, the detection angle is changed and focus adjustment is performed. As described above, in the image acquisition device 1, the detection angle is easily changed and the focus position P is set to the thin film only by the moving mechanism 4 that moves the imaging unit 2 in two directions without providing a mechanism for rotating the imaging unit 2. Can be placed on the pattern.

  In addition, a pattern image having a high contrast between the pattern and the background can be acquired without changing the wavelength of light applied to the imaging region 90. This eliminates the need for a complicated structure for changing the wavelength, or the design and complicated adjustment of an optical system corresponding to multi-wavelength light, and the manufacturing cost of the image acquisition device 1 can be reduced. Further, for example, even when a photosensitive resist is included in the layer on the pattern, a pattern image can be easily obtained while avoiding light having an unusable wavelength.

  In the image acquisition device 1, the movement mechanism 4 is controlled using the correction table 331 in synchronization with the rotation of the drum 11, so that the focus position P conjugate with the light receiving surface of the line sensor 231 is always accurately on the thin film pattern. Can be placed well. As a result, a pattern image having a high contrast can be stably acquired. Moreover, in the image acquisition apparatus 1 using the drum 11, the installation area of the apparatus can be reduced as compared with an apparatus that acquires an image of a web conveyed in the horizontal direction. Depending on the design of the image acquisition device 1, a sensor that detects the distance between the light receiving unit 23 and the web 9 in the direction of the optical axis J2 is provided, and the light receiving unit 23 follows the optical axis J2 based on the output of the sensor. The focus adjustment may be performed in real time when the pattern image is acquired.

  In the image acquisition device 1, in addition to the pattern inspection, a pattern image may be displayed. For example, as indicated by a broken-line rectangle in FIG. 6, the display control unit 34 is connected to the light receiving unit 23, and the display 35 is connected to the display control unit 34. In the display of the pattern image, an imaging region 90 is arranged in the vicinity of the region on the web 9 designated by the operator (the detection angle is a set angle), and the line of the light receiving unit 23 is conveyed while the web 9 is conveyed. A line image of the imaging region 90 is repeatedly acquired by the sensor 231. The line image data is input to the display control unit 34. Thereby, pattern image data indicating the thin film pattern in the designated region is acquired, and the pattern image is displayed on the display 35. The display control unit 34 and the display 35 may be provided in other image acquisition devices.

  FIG. 8 is a diagram illustrating another example of the imaging unit, and is a rear view of the imaging unit. In the imaging unit 2a of FIG. 8, the structure of the light irradiation unit 21a is different from that of the light irradiation unit 21 of FIG. 2, and a light irradiation unit rotating mechanism 22 that rotates the light irradiation unit 21a is provided. The light irradiation unit 21 a includes a plurality of LEDs arranged in the Y direction, and an optical system that uniformizes the light from the LEDs and guides the light to the imaging region 90.

  The light irradiation unit rotation mechanism 22 has an arcuate guide plate 221 centered on the focus position P, and the guide plate 221 is fixed to the barrel 233 of the light receiving unit 23. The guide plate 221 is a plate member parallel to the X direction and the Z direction. The light irradiation unit 21a is provided with a gear 223 and two guide rollers 224 that rotate about an axis parallel to the Y direction. In the guide plate 221, a rack 222 is provided on the outer arc-shaped edge with respect to the focus position P (that is, the edge farther from the focus position P of the two arc-shaped edges), and the gear 223 is attached to the rack 222. Match. Further, a guide groove with which the guide roller 224 is engaged is formed on the inner arc-shaped edge of the guide plate 221.

  In the imaging unit 2, the light irradiation unit 21 a moves along the arc-shaped edge of the guide plate 221 by rotating a gear 223 by a motor (not shown). That is, the light irradiation unit rotating mechanism 22 rotates the light irradiation unit 21a around an axis (virtual axis) parallel to the imaging region 90 and passing through the focus position P. The gear 223 and the guide roller 224 are a part of the light irradiation unit rotating mechanism 22. In the imaging unit 2a, the irradiation angle θ1 is changed by the light irradiation unit rotating mechanism 22 with the angle θ1 formed by the optical axis J1 extending from the light irradiation unit 21a to the imaging region 90 and the normal line N of the web 9 as the irradiation angle. .

  In pattern image acquisition in the image acquisition device 1 having the imaging unit 2a, when the detection angle θ2 is set as the set angle, the light irradiation unit rotation mechanism 22 rotates the light irradiation unit 21a, so that the irradiation angle θ1 is also set. Changed to set angle. Thereby, a pattern image with high contrast can be acquired. On the other hand, from the viewpoint of simplifying the control of the image acquisition device 1, it is preferable to employ the light irradiation unit 21 of FIG. 2 and omit the mechanism that rotates the light irradiation unit 21.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made.

  In the process of step S11 of FIG. 7, the same on the web 9 is obtained by moving the imaging units 2 and 2a along the outer surface 111 of the drum 11 by the moving mechanism 4 in synchronization with the movement of the web 9 by the drum 11. Line images may be acquired at a plurality of detection angles with respect to the position. In this case, an image whose contrast changes along the direction perpendicular to the line is acquired, and the operator can determine the set angle with reference to the image. Further, when the same pattern continues in the longitudinal direction of the web 9, an image similar to the above image is acquired without transporting the web 9 by the drum 11 when acquiring line images at a plurality of detection angles. Is possible.

  Further, in the image acquisition device 1, a profile may be acquired by providing a film thickness meter (optical interference type spectral film thickness meter or ellipsometer).

  In the image acquisition device 1, the imaging units 2 and 2a may be attached to the moving mechanism 4 so that the optical axis J2 of the light receiving unit 23 is parallel to the ZX plane and inclined with respect to the Z direction. Further, depending on the design of the image acquisition device 1, a mechanism for assisting rotation of the imaging units 2 and 2 a about an axis parallel to the central axis K of the drum 11 may be provided.

  When a pattern image having a high contrast can be acquired by using one of p-polarized light and s-polarized light as compared with the case where polarized light is not used, polarized light is captured between the imaging region 90 and the light receiving unit 23. A child may be placed. In this case, only p-polarized light or s-polarized light out of the reflected light from the web 9 enters the light receiving unit 23. In addition, a rotation mechanism that rotates the polarizer around the optical axis J2 may be provided, and the polarized light incident on the light receiving unit 23 may be switched. Further, the first pattern image may be acquired based on the p-polarized light, and the second pattern image may be acquired based on the s-polarized light. In this case, for example, the product of the value of each pixel of the first pattern image and the value of the corresponding pixel of the second pattern image is obtained, and an image having the product as the pixel value is obtained as the pattern image. In such a pattern image, since two different types of images are used, the influence of noise or the like in the image is reduced.

  The film structure formed on the substrate may be various, and usually has a more complicated structure than that exemplified in the above embodiment. The pattern to be inspected (or display target) is not limited to one type, and may be a plurality of types. In this case, when the patterns to be inspected are inspected, other patterns overlapping with this pattern are treated as the background.

  In the above embodiment, the background has been described as having one type, but the background is not limited to one type. When there are a plurality of types of backgrounds, a profile is obtained for each background, and a detection angle at which the contrast is high for any background is determined.

  The composition of the thin film pattern may be formed of other materials as long as it has a certain degree of transparency to the irradiation light, and is not necessarily transparent to visible light. The pattern is not limited to the transparent electrode, and may be a pattern for other uses. However, the application of the image acquisition device is particularly suitable for inspection or display of a pattern image of a transparent electrode that cannot be shaded even when irradiated with visible light. Further, the base material may be formed of a material other than resin.

  The wavelength of the light emitted from the light irradiation unit is not limited to a single wavelength, and light of a plurality of wavelengths may be selectively emitted. The light source may be provided with an LD instead of the LED. Further, a combination of a lamp such as a halogen lamp and a filter may be provided as the light source.

  The two moving directions of the imaging units 2 and 2 a by the moving mechanism 4 do not necessarily have to be orthogonal if they are perpendicular to the central axis K of the drum 11.

  The configurations in the above-described embodiments and modifications may be combined as appropriate as long as they do not contradict each other.

DESCRIPTION OF SYMBOLS 1 Image acquisition apparatus 4 Moving mechanism 9 Web 11 Drum 21,21a Light irradiation part 23 Light receiving part 30 Overall control part 33 Storage part 90 Imaging area 111 Outer side surface 231 Line sensor 232 Optical system 331 Correction table J2 Optical axis K Center axis N method Line P Focus position α Angle range θ2 Detection angle

Claims (3)

An image acquisition device for acquiring an image of a thin film pattern formed on a sheet-like substrate,
A drum having an outer surface that is a cylindrical surface centered on a predetermined central axis, and transporting the substrate along the outer surface by rotating about the central axis;
A light irradiator that emits light having a wavelength that is transmissive to the thin film pattern toward a linear imaging region parallel to the central axis on the substrate held by the drum;
A light receiving unit having a line sensor and an optical system that guides light from the imaging region to the line sensor;
A moving mechanism that moves the light irradiation unit and the light receiving unit in two directions perpendicular to the central axis and intersecting each other;
By controlling the moving mechanism, the detection angle formed by the optical axis of the optical system and the normal line of the base material is changed, and a position conjugate with the light receiving surface of the line sensor is placed on the optical axis on the thin film. A control unit arranged on the pattern;
An image acquisition apparatus comprising: The image acquisition device according to claim 1,
The light irradiation unit irradiates the light toward the imaging region in a predetermined angle range centered on an axis parallel to the imaging region and passing through the conjugate position;
An image acquisition characterized in that an angular position inclined by the detection angle about the axis on the opposite side of the optical axis from the normal line on a plane perpendicular to the axis is included in the predetermined angle range. apparatus. The image acquisition device according to claim 1 or 2,
A storage unit that stores a correction table that indicates a shake amount in each portion in the circumferential direction around the central axis on the outer surface of the drum;
The image acquisition apparatus, wherein the control unit controls the moving mechanism using the correction table in synchronization with rotation of the drum.

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