Imaging device and inspection device

Abstract

Provided is a novel imaging device capable of appropriately acquiring a fluorescence image and a reflected light image of an object. The imaging device (2) is provided with: a stage (21) for holding an object; a first emission unit (3) that emits first emission light, which is ultraviolet light; a second emission unit (4) that emits second emission light, which is light having a wavelength region different from that of the ultraviolet light; a cross-shaped dichroic prism (5), which is a quadrangular prism having first to fourth side surfaces (51, 54), and which emits the first emission light from a third side surface (53) to the first side surface and guides the first emission light to an imaging region (90) on an object, and emits the second emission light from the third side surface (53) to the imaging region and guides the second emission light from the third side surface (53) to the imaging region; and an imaging unit (7) that receives fluorescent light generated in the imaging region when the first emission light is irradiated to the imaging region, and that receives reflected light of the second emission light in the imaging region when the second emission light is irradiated to the imaging region.

Description

[0001] [Refer to related applications]

[0002] This application claims the benefit of priority to Japanese Patent Application JP2024-157307, filed on September 11, 2024, and invokes the entire disclosure of that application. Technical Field

[0003] This invention relates to a photographing device and an inspection device. Background Technology

[0004] Conventional inspection devices are used to acquire images of various objects and inspect them. For example, in the inspection system disclosed in Japanese Patent Application Publication No. 2016-194434 (Document 1), inspection light is irradiated from around the object by coaxial illumination and dome illumination, and a zone camera receives the inspection light reflected along the normal direction of the object to capture a color image. Furthermore, defects are inspected on the object based on this color image. In addition, Japanese Patent Application Publication No. 2006-300545 (Document 2) discloses a position measuring device for alignment marks, etc. In this device, a cross dichroic prism is used to combine the R, G, and B rays into a single optical axis and illuminate the object under inspection. Other cross dichroic prisms are used to separate the light from the object under inspection into R, G, and B rays, which are then imaged onto multiple CCDs (charge-coupled devices).

[0005] In recent years, with the increasing precision of patterns drawn on printed circuit boards (PCBs), defects known as dark short circuits sometimes occur. A dark short circuit defect refers to a short circuit caused by a thin layer (residual) of conductive material present in areas where conductive material is not designed to exist (background areas), resulting in continuity between conductive parts. When illuminating the PCB with light and capturing the reflected light from the conductive parts to obtain a reflected light image, it is difficult to distinguish between the two because neither the normal background area nor the dark short circuit defect can guide the reflected light to the capturing unit. Therefore, it is considered to irradiate the PCB with ultraviolet light (UV light) and capture the excitation emission (fluorescence) in the background area to obtain a fluorescence image for the detection of dark short circuit defects. Thus, an imaging device capable of appropriately acquiring both fluorescence and reflected light images is needed. Summary of the Invention

[0006] The purpose of this invention is to provide a novel imaging device capable of appropriately acquiring fluorescent and reflected light images of an object.

[0007] One embodiment of the present invention is a photographing device for photographing an object, wherein the photographing device comprises: a stage for holding the object; a first emitting section for emitting ultraviolet light, i.e., first emitted light; a second emitting section for emitting light with a wavelength region different from ultraviolet light, i.e., second emitted light; a cross-shaped dichroic prism, which is a quadrangular prism having first to fourth sides, from which the first emitted light incident on the first side is emitted from the third side and guided to a photographing area on the object, and from which the second emitted light incident on the second side is emitted from the third side and guided to the photographing area; and a photographing section for receiving fluorescence generated in the photographing area when the first emitted light illuminates the photographing area, and for receiving reflected light of the second emitted light in the photographing area when the second emitted light illuminates the photographing area.

[0008] According to the present invention, a novel imaging device is provided that can appropriately acquire fluorescence images and reflected light images of an object.

[0009] The second embodiment of the present invention is the imaging device of the first embodiment, wherein the dichroic prism has a first mirror and a second mirror that intersect each other. The first mirror reflects the first emitted light and transmits the second emitted light. The second mirror transmits the first emitted light and reflects and transmits the second emitted light and the fluorescence. Light from the imaging area is incident on the third side of the dichroic prism, and a portion of the light is emitted from the fourth side of the dichroic prism and guided to the imaging unit.

[0010] The third embodiment of the present invention is the imaging device of the second embodiment, wherein in the cross-shaped dichroic prism, the first side face is opposite to the second side face, and the third side face is opposite to the fourth side face.

[0011] The fourth embodiment of the present invention is the same as the first embodiment (or any one of the first to third embodiments) of the imaging device, wherein the imaging unit has a line sensor as the imaging element, and the cross-shaped dichroic prism is a long strip along the direction of the first to fourth side surfaces.

[0012] The fifth embodiment of the present invention is the same as the first embodiment (or any one of the first to fourth embodiments) of the imaging device, wherein the light source of the first emission part is a laser diode.

[0013] The sixth embodiment of the present invention is an imaging device of embodiment one (or any one of embodiments one to five), wherein the imaging device further comprises: a dome-shaped illumination section disposed on the optical axis between the third side surface of the cross dichroic prism and the imaging area, illuminating the imaging area from the dome-shaped surface covering the imaging area, and a light-transmitting section provided at a position on the surface intersecting the optical axis.

[0014] The seventh embodiment of the present invention is the imaging device of the first embodiment (or any one of the first to sixth embodiments), wherein the object is a printed circuit board.

[0015] The eighth embodiment of the present invention is an inspection device having any one of the imaging devices in embodiments one to seven, and an inspection unit for inspecting images acquired by said imaging device.

[0016] The above-mentioned objects, other objects, features, methods, and advantages will become more apparent from the following detailed description of the invention with reference to the accompanying drawings. Attached Figure Description

[0017] Figure 1 This is a diagram showing the structure of the inspection device.

[0018] Figure 2 This is a magnified representation of an X-ray prism.

[0019] Figure 3 This is a cross-sectional view of the printed circuit board.

[0020] Figure 4 This is a graph showing the amount of ultraviolet light and fluorescence when using LEDs.

[0021] Figure 5 This is a graph showing the amount of ultraviolet light and fluorescence when using a laser diode.

[0022] Explanation of reference numerals in the attached figures

[0023] 1 Inspection device

[0024] 2. Filming device

[0025] 3 First ejection section

[0026] 4 Second ejection section

[0027] 5-cross dichroic prism

[0028] 6 Dome-shaped lighting section

[0029] 7 Filming Department

[0030] 9Printed substrate

[0031] 11 Inspection Department

[0032] 21 Platforms

[0033] 51-54 (side views of the cross-shaped dichroic prism)

[0034] 56 First mirror membrane

[0035] 57 Second mirror film

[0036] 71 camera elements

[0037] 90 shooting area

[0038] 610 opening

[0039] 611 dome inner surface

[0040] J1 optical axis Detailed Implementation

[0041] Figure 1 This is a diagram showing the structure of an inspection device 1 according to an embodiment of the present invention. Figure 1 The inspection apparatus 1 is an optical appearance inspection apparatus for inspecting the appearance of the printed circuit board 9. The inspection apparatus 1 can also be used to inspect substrates other than the printed circuit board 9, or it can be used to inspect objects other than substrates. In the following description, Figure 1 The up and down direction is simply referred to as the "up and down direction", but the up and down direction is not limited to the direction of gravity.

[0042] The inspection apparatus 1 includes an imaging device 2 and a computer 10. The computer 10, including a CPU, executes a prescribed program to implement an inspection unit 11 and a control unit (not shown). The inspection unit 11 inspects the image acquired by the imaging device 2. That is, it uses the image to detect defects in the printed circuit board 9. The control unit is responsible for controlling the entire inspection apparatus 1. All or part of the inspection unit 11 and the control unit can also be implemented using dedicated circuitry.

[0043] The imaging device 2 includes a control unit, a stage 21, a stage moving mechanism 22, a first ejector 3, a second ejector 4, a cross-shaped dichroic prism 5 (hereinafter referred to as "X-prism 5"), a dome-shaped illumination unit 6, and an imaging unit 7. Figure 1 In this example, the control unit of the inspection device 1 also serves as the control unit of the imaging device 2. The stage 21 holds the object to be imaged by the imaging device 2, namely the printed circuit board 9. Figure 1 In this example, the printed circuit board 9 is supported from below by the stage 21 for holding. The printed circuit board 9 can be held by the stage 21 by attraction or adsorption. The stage moving mechanism 22 includes a motor and a ball screw, etc., to move the stage 21. The direction of movement of the stage 21 by the stage moving mechanism 22 is, for example, two mutually orthogonal directions along the main surface of the printed circuit board 9 (and...). Figure 1 (The vertical directions are perpendicular to each other). The stage moving mechanism 22 can also be a mechanism with a linear motor, etc.

[0044] X-prism 5 is positioned above stage 21. Typically, X-prism 5 is formed by fitting four right-angled triangular prisms, having the characteristics of a tetragonal prism (in...). Figure 1In this example, the shape is that of a regular square prism. The interfaces of the four prisms intersect in an X-shape. In other words, in the X-prism 5, two faces intersect in an X-shape. Mirror films 56 and 57, which are dielectric multilayer films, are formed on these two faces. The mirror film 56 on one surface (hereinafter referred to as "first mirror film 56") is a dichroic mirror that reflects ultraviolet light and transmits visible light. In one example of the first mirror film 56, the reflectivity of light with wavelengths of 360–409 nm at an incident angle of 45° is greater than 98%.

[0045] The mirror film 57 on the other surface (hereinafter referred to as "second mirror film 57") is a semi-reflective mirror (or dichroic mirror) that transmits ultraviolet light and reflects and transmits visible light. In one example of the second mirror film 57, the reflectivity of light with wavelengths of 360–409 nm at an incident angle of 45° is less than 0.2%, and the reflectivity of light with wavelengths of 410–860 nm is 50%. In this embodiment, light with wavelengths of 360–409 nm belongs to ultraviolet light, and light with wavelengths of 410–860 nm belongs to visible light.

[0046] The X-prism 5 has four side faces and two end faces. The four side faces include a first side face 51, a second side face 52, a third side face 53, and a fourth side face 54. Figure 1 In the X-prism 5, the first side 51 faces left, the second side 52 faces right, the third side 53 faces downward, and the fourth side 54 faces upward. Thus, the first side 51 is opposite to the second side 52, and the third side 53 is opposite to the fourth side 54. A general anti-reflective coating (AR coating) is formed on the first side 51 to the fourth side 54. In one example of the anti-reflective coating, the reflectivity of light with wavelengths of 360–860 nm at an incident angle of 0° is less than 0.2%. The X-prism 5 is longer in the direction along the first side 51 to the fourth side 54 (the direction between the two end faces, hereinafter referred to as the "prism length direction"). Figure 1 The length direction of the prism is perpendicular to the plane of the paper. When viewed along the length direction of the prism, the first mirror film 56 and the second mirror film 57 are respectively positioned on the two diagonals of the quadrilateral forming the shape of the X-prism 5, intersecting at an angle of 90°. The angle between the first mirror film 56 and each of the first side surface 51 to the fourth side surface 54 is 45°. Similarly, the angle between the second mirror film 57 and each of the first side surface 51 to the fourth side surface 54 is also 45°.

[0047] The first emitting section 3 is positioned opposite the first side surface 51 of the X-prism 5 and includes a light source section 31 and an optical system 32. The light source section 31 emits ultraviolet light, i.e., the first emitted light. Preferably, the light source section 31 includes one or more laser diodes (also called LDs or semiconductor lasers). As described later, the wavelength range of a laser diode is narrower than that of an LED, etc. The wavelength of the first emitted light is, for example, 365 nm or 405 nm. The optical system 32 shapes the first emitted light and guides it toward the X-prism 5. Specifically, the first emitted light emitted from the light source section 31 is shaped by the optical system 32 and incident on the first side surface 51 of the X-prism 5 so that its beam profile extends along the length of the prism. The optical axis of the optical system 32 is approximately perpendicular to the first side surface 51.

[0048] The second emission section 4 is positioned opposite the second side surface 52 of the X-prism 5, and includes a light source section 41 and an optical system 42. The light source section 41 emits visible light, i.e., the second emitted light. The second emitted light can also be light other than ultraviolet or visible light. In this embodiment, the light source section 41 includes a plurality of LEDs (light-emitting diodes). The plurality of LEDs are arranged along the length of the prism. The wavelength of the second emitted light is, for example, in the range of 410–860 nm. The optical system 42 guides the second emitted light to the X-prism 5. Figure 1 In this example, the optical system 42 has a diffuser and a linear Fresnel lens to homogenize and shape the second emitted light from the light source 41, so that it is incident on the second side surface 52 of the X-prism 5, so that the profile of its beam extends along the length of the prism. The optical axis of the optical system 42 is substantially perpendicular to the second side surface 52.

[0049] As described later, the first emitted light from the first emission section 3 and the second emitted light from the second emission section 4 are incident on the X-prism 5, and are emitted from the third side surface 53 of the X-prism 5, illuminating a region 90 (hereinafter referred to as the "image area 90") extending along the length of the prism on the upper surface of the printed circuit board 9. The image area 90 is the region where an image is captured using the image capture section 7. In the first emission section 3, the first emitted light is guided to the image area 90 along the optical axis from the light source section 31 through the optical system 32 and the X-prism 5 toward the printed circuit board 9. In the second emission section 4, the second emitted light is guided to the image area 90 along the optical axis from the light source section 41 through the optical system 42 and the X-prism 5 toward the printed circuit board 9. Between the third side surface 53 of the X-prism 5 and the printed circuit board 9, the optical axis of the first emission section 3 and the optical axis of the second emission section 4 are aligned. Figure 1 In the figure, the optical axis between the third side surface 53 of the X-prism 5 and the printed substrate 9 is marked with reference numeral J1. The optical axis J1 is approximately perpendicular to the third side surface 53.

[0050] A dome-shaped illumination unit 6 is positioned on the optical axis J1 between the third side surface 53 of the X-prism 5 and the imaging area 90. The dome-shaped illumination unit 6 has a dome-shaped body 61 and a light source unit 62. The dome-shaped body 61 is a dome-shaped (or hemispherical or bowl-shaped) rotating body with the optical axis J1 approximately centered, opening downwards. The dome-shaped body 61 has a dome-shaped inner surface 611 (hereinafter referred to as "the dome inner surface 611"). The dome inner surface 611 of the dome-shaped body 61 is a reflective surface. The dome inner surface 611 covers the imaging area 90 of the printed circuit board 9. The position of the dome inner surface 611 intersecting the optical axis J1 (…) Figure 1 In the example, an opening 610 is formed on the upper part of the dome body 61. An X-prism 5 is positioned near the top of the opening 610. When viewed along the optical axis J1, the size of the opening 610 largely overlaps with that of the X-prism 5, and like the X-prism 5, it is longer in the prism's length direction. The first and second emitted light rays, emitted from the third side surface 53 of the X-prism 5, enter the dome body 61 through the opening 610 and illuminate the imaging area 90. As described above, the opening 610 is a light-transmitting portion for light to pass through.

[0051] At the lower annular end of the dome body 61, an annular flange 612 protrudes across the entire circumferential optical axis J1. A plurality of light sources (e.g., LEDs) 621 of the light source unit 62 are arranged circumferentially (around the optical axis J1) on the upper surface of the annular flange 612. The light emitted from the light sources 621 is visible light, just like the second emitted light. The light from the plurality of light sources 621 is reflected (diffuse or specular) by the inner surface 611 of the dome and illuminates the imaging area 90 covered by the inner surface 611 of the dome. That is, the illumination light from the inner surface 611 of the dome illuminates the imaging area 90 in various directions different from the optical axis J1. In the imaging device 2, an illumination unit is constituted by a first emission unit 3, a second emission unit 4, an X-prism 5, and a dome-shaped illumination unit 6.

[0052] The imaging unit 7 is positioned opposite the fourth side surface 54 of the X-prism 5 and includes an imaging element 71 and an imaging optical system 72. In this embodiment, the imaging element 71 is a line sensor, which extends along the length of the prism. The imaging optical system 72 includes a plurality of lenses, and light emitted from the fourth side surface 54 of the X-prism 5 is incident on the imaging optical system 72. The optical axis of the imaging optical system 72 is substantially perpendicular to the fourth side surface 54. As described, the imaging optical system 72 forms an image of the imaging area 90 on the imaging surface of the imaging element 71. Thus, a line image representing the imaging area 90 is acquired. Alternatively, an area sensor can also be used as the imaging element 71 in the imaging unit 7.

[0053] During image acquisition using the imaging device 2, the stage moving mechanism 22 continuously moves the printed circuit board 9 along a moving direction perpendicular to the imaging area 90 (more precisely, perpendicular to the length direction of the prism and along the main surface of the printed circuit board 9). In the imaging element 71, line images are repeatedly acquired parallel to the movement of the printed circuit board 9 in the moving direction, thereby acquiring a two-dimensional multi-grayscale image of the printed circuit board 9 (hereinafter referred to as a "captured image"). In the inspection device 1 of this embodiment, a first captured image is acquired when the emission of the first emitted light from the first emission section 3 is set to ON, and the emission of light from the second emission section 4 and the dome-shaped illumination section 6 is set to OFF. Furthermore, a second captured image is acquired when the emission of the first emitted light from the first emission section 3 is set to OFF, and the emission of light from the second emission section 4 and the dome-shaped illumination section 6 is set to ON.

[0054] Figure 2 This is a magnified view of the X-prism 5, with the first emitting section 3 and the second emitting section 4 represented by blocks. As described above, the X-prism 5 has a first mirror film 56 and a second mirror film 57 that intersect each other. The first mirror film 56 reflects ultraviolet light and transmits visible light. The second mirror film 57 transmits ultraviolet light and reflects and transmits visible light. When acquiring the first image, the first emitted light (ultraviolet light) incident from the first emitting section 3 onto the first side surface 51 is reflected by the first reflecting mirror film 56 and illuminates the imaging area 90 of the printed circuit board 9 via the third side surface 53. Figure 2 In the image, the first emitted light is represented by a thick dashed line.

[0055] Figure 3 This is a cross-sectional view of the printed circuit board 9. The upper surface of the printed circuit board 9 includes, for example, a region where conductive portions 91 are formed of a conductive material such as copper, and a region 92 (hereinafter referred to as "background region 92") where no conductive material is designed to be present. The background region 92 is the area where the substrate or insulating layer of the printed circuit board 9 is exposed. In the background region 92, for example, a material containing resin (epoxy resin, etc.) is exposed. Figure 3 In the example, although it is background region 92, it also includes dark short circuit defects 93 where a relatively thin layer of conductive material exists (residual) and conduction occurs between conductive parts 91.

[0056] Using the first emitted light illuminating the imaging area 90, fluorescence (fluorescent light) is generated in the background area 92, excluding the dark short-circuit defect 93. Most of the fluorescence is visible light. On the other hand, in the conductive part 91 and the dark short-circuit defect 93, i.e., the area covered by conductive material, the first emitted light is reflected (mainly specular reflection). A portion of the fluorescence and a portion of the reflected light from the first emitted light are incident along the optical axis J1 onto the third side surface 53 of the X-prism 5.

[0057] In the X-prism 5, a portion of the fluorescence incident on the third side surface 53 is reflected by the second mirror film 57 and directed toward the second emission section 4, while the remaining portion (the residual light) passes through the second mirror film 57. Fluorescence passes through the first mirror film 56. The fluorescence that has passed through the second and first mirror films 57 exits from the fourth side surface 54 of the X-prism 5 and is incident on the imaging optical system 72 of the imaging section 7. On the other hand, the reflected light of the first emitted light incident on the third side surface 53 is reflected by the first reflecting mirror film 56 and directed toward the first emission section 3. Therefore, the reflected light of the first emitted light does not enter the imaging optical system 72 of the imaging section 7. As a result, in the imaging section 7, a fluorescence image representing only the fluorescence in the background area 92 is acquired as the first captured image.

[0058] When acquiring the second image, a portion of the second emitted light (visible light) incident from the second emission section 4 onto the second side surface 52 passes through the second mirror film 57 and faces the first emission section 3, while the remaining portion (the other portion) is reflected by the second mirror film 57. The reflected second emitted light then illuminates the imaging area 90 of the printed circuit board 9 via the third side surface 53. Figure 2 In the image, the second emitted light is represented by a thick solid line. Additionally, illumination light from the inner surface 611 of the dome-shaped illumination unit 6 also illuminates the shooting area 90.

[0059] The second emitted light illuminating the imaging area 90 is almost not reflected in the background area 92 except for the dark short-circuit defect 93 (specular reflection). On the other hand, the second emitted light is reflected in the conductive part 91 and the dark short-circuit defect 93. A portion of the reflected light from the second emitted light is incident on the third side surface 53 of the X-prism 5 along the optical axis J1. At this time, the reflected light from the upper surface of the conductive part 91 is directed towards the third side surface 53 along the optical axis J1, but since the reflected light from the side surface of the conductive part 91 and the dark short-circuit defect 93 is directed in a direction different from the optical axis J1, it hardly incident on the third side surface 53. In addition, the illumination light illuminating the imaging area 90 from the inner surface 611 of the dome is used for dark field illumination, and the light mainly reflected from the edge of the upper surface of the conductive part 91 is incident on the third side surface 53 of the X-prism 5 along the optical axis J1. Furthermore, the upper surface of the conductive part 91 can be circular. In this case, the illumination light from the dome-shaped illumination part 6 can be used to make a large range of reflected light from the upper surface incident on the X-prism 5.

[0060] In the X-prism 5, a portion of the reflected light incident on the third side surface 53 (reflected light from the second emitted light and reflected light from the illumination light from the inner surface 611 of the dome) is reflected by the second mirror film 57 and directed towards the second emission section 4, while the remaining portion (the remaining light) passes through the second mirror film 57. This reflected light passes through the first mirror film 56. The reflected light passing through the second mirror film 57 and the first mirror film 56 exits from the fourth side surface 54 of the X-prism 5 and is incident on the imaging optical system 72 of the imaging section 7. Thus, in the imaging section 7, an image of the reflected light representing the upper surface of the conductive section 91 is acquired as a second image.

[0061] In the inspection unit 11, dark short-circuit defects 93 are detected by comparing fluorescence images and reflected light images. As described above, since conductive material is present in dark short-circuit defects 93, no fluorescence is generated. Furthermore, since the reflected light from dark short-circuit defects 93 is directed in a direction different from the optical axis J1, it is not guided to the imaging unit 7. Therefore, in one example of the inspection process, areas darker than a predetermined threshold in both the fluorescence image and the reflected light image are detected as dark short-circuit defects 93. The detection of dark short-circuit defects 93 using fluorescence and reflected light images can also be performed using other methods. Additionally, fluorescence images can also be used in the inspection unit 11 to detect defects other than dark short-circuit defects 93.

[0062] As explained above, Figure 1 The imaging device 2 includes a first emission section 3, a second emission section 4, an X-prism 5, and an imaging section 7. The first emission section 3 emits ultraviolet light, i.e., first emitted light. The second emission section 4 emits light with a wavelength range different from that of ultraviolet light, i.e., second emitted light. The X-prism 5 is a quadrangular prism having a first side surface 51 to a fourth side surface 54. The first emitted light incident on the first side surface 51 is emitted from the third side surface 53 and guided to the imaging area 90 on the printed circuit board 9. The second emitted light incident on the second side surface 52 is emitted from the third side surface 53 and guided to the imaging area 90. When the first emitted light illuminates the imaging area 90, the imaging section 7 receives the fluorescence generated in the imaging area 90. When the second emitted light illuminates the imaging area 90, the imaging section 7 receives the reflected light of the second emitted light in the imaging area 90. Thus, the imaging device 2 can be realized to appropriately acquire fluorescence images and reflected light images of the printed circuit board 9.

[0063] Preferably, the X-prism 5 has a first mirror film 56 and a second mirror film 57 that intersect each other. The first mirror film 56 reflects a first emitted light and transmits a second emitted light. The second mirror film 57 transmits the first emitted light and reflects and transmits the second emitted light and fluorescence. Furthermore, light from the imaging area 90 is incident on the third side surface 53 of the X-prism 5, and a portion of this light exits from the fourth side surface 54 of the X-prism 5 and is guided to the imaging unit 7. In this structure, the X-prism 5 can be used to block ultraviolet light directed toward the imaging unit 7, and a fluorescence image can be appropriately acquired. In addition, the characteristics of the first mirror film 56 and the second mirror film 57 can be changed as needed.

[0064] Preferably, the imaging device 2 also includes a dome-shaped illumination section 6. The dome-shaped illumination section 6 is disposed on the optical axis J1 between the third side surface 53 of the X-prism 5 and the imaging area 90. Furthermore, illumination light is irradiated onto the imaging area 90 from the dome-shaped surface (inner dome surface 611) covering the imaging area 90, and an opening 610 is formed on this surface intersecting the optical axis J1. In the imaging device 2, by utilizing the dome illumination of the dome-shaped illumination section 6, a preferred reflected light image near the edge of the conductive portion 91 can be obtained, allowing for visual identification.

[0065] Here, similar to the device described in Japanese Patent Application Publication No. 2016-194434 (Document 1 above), a comparative example photographing apparatus is assumed to be provided, which includes a visible light emitting section for coaxial incident illumination and a dome-shaped illumination section for dome illumination. The comparative example photographing apparatus is... Figure 1 In the imaging apparatus 2, the first emission section 3 is omitted, and the X-prism 5 is replaced with a semi-reflective mirror. In the imaging apparatus of the comparative example, an ultraviolet light emission section needs to be added in order to observe fluorescence. In this case, for example, it is considered to arrange a semi-reflective mirror for the visible light emission section and a dichroic mirror for the ultraviolet light emission section sequentially between the imaging section and the dome-shaped illumination section; however, the illumination unit between the imaging section and the printed circuit board tends to become more complex and larger. In addition, in the imaging section, high resolution and telecentricity are required, and there is a trend for the distance (working distance: WD) between the imaging section and the printed circuit board to become shorter. Therefore, the space allocated to the illumination unit is limited, and the arrangement of the illumination unit becomes difficult.

[0066] In contrast, Figure 1In the imaging device 2, an X-prism 5 is provided between the imaging unit 7 and the dome-shaped illumination unit 6. A first emitting unit 3 and a second emitting unit 4, emitting light with different wavelength regions, are provided on the left and right sides of the X-prism 5, with the first side 51 where the first emitted light is incident and the second side 52 where the second emitted light is incident facing each other. Therefore, in the imaging device 2 capable of acquiring fluorescence and reflected light images using coaxial incident illumination, the illumination unit disposed between the imaging unit 7 and the printed circuit board 9 can be prevented from becoming overly complex and large, i.e., space-saving of the illumination unit can be achieved. Furthermore, as with the imaging device of the comparative example described above, when using a semi-reflective mirror or a dichroic mirror, ghosting is easily generated in the image acquired by the imaging unit. On the other hand, in the imaging device 2 using the X-prism 5, ghosting in fluorescence and reflected light images can be suppressed.

[0067] However, in the background area 92 of the printed circuit board 9, the amount of fluorescence generated by irradiating with ultraviolet light is usually less than the amount of reflected light from the conductive part 91, etc. Therefore, when acquiring a fluorescence image, in order to make the imaging speed, that is, the relative movement speed of the imaging element 71 (line sensor) relative to the printed circuit board 9 (scanning speed), the same as when acquiring a reflected light image, it is necessary to increase the amount of fluorescence generated (excitation light amount).

[0068] Figure 4 and Figure 5 This is a graph showing the amount of ultraviolet light irradiated onto the printed substrate 9 and the amount of fluorescence generated. The solid line L1 represents the amount of ultraviolet light irradiated, and the dashed line L2 represents the amount of fluorescence. Figure 4 This indicates the amount of light emitted when an LED emitting ultraviolet light is used as the light source 31 of the first emission section 3. Figure 5 This indicates the amount of light emitted when a laser diode emitting ultraviolet light is used as the light source unit 31. Figure 4 The right side and Figure 5 In the figure, the boundary of the wavelength region of light transmitted through the first mirror film 56 of the X-prism 5 is given the reference numeral B1.

[0069] like Figure 4 As shown on the left, the ultraviolet light emitted from the LED has a wide wavelength range (spectral width), and the resulting fluorescence also has a wide wavelength range. In imaging device 2, as... Figure 4 As shown on the right, only light with wavelengths greater than wavelength B1 passes through the first mirror film 56 and is introduced into the imaging unit 7. Therefore, in Figure 4 In the example, only a portion of the generated fluorescence is used for acquiring the fluorescence image. In other words, of the ultraviolet light emitted from the LED, only a portion is used for fluorescence image acquisition. Figure 4To the right, the wavelength region indicated by arrow A1 is the effective range for acquiring fluorescence images, while the wavelength region indicated by arrow A2 is the ineffective range. Thus, the ultraviolet light emitted from the LED contains a significant amount of wavelengths ineffective for acquiring fluorescence images. To maintain the same shooting speed as when acquiring reflected light images, a large amount of light energy needs to be irradiated onto the printed circuit board 9 to obtain a high excitation light intensity. In this case, the printed circuit board 9 may be damaged due to heat generation.

[0070] On the other hand, such as Figure 5 As shown, the ultraviolet light emitted from the laser diode has a narrow wavelength range. Therefore, by using a laser diode, ultraviolet light can be irradiated onto the printed circuit board 9, containing a large number of wavelengths effective for acquiring fluorescence images and a small number of wavelengths ineffective for acquiring fluorescence images. Figure 5 In the example, the wavelength region of the light emitted from the laser diode almost does not overlap with the wavelength region of the fluorescence. In the imaging device 2, the light source of the first emission section 3 is a laser diode, thereby reducing the light energy irradiating the printed circuit board 9 and generating sufficient fluorescence. As a result, damage to the printed circuit board 9 can be reduced while appropriately acquiring a fluorescence image. Furthermore, depending on the type of object being photographed by the imaging device 2, a light source other than a laser diode (LED, solid-state laser, lamp, etc.) can be used in the first emission section 3. Light sources other than LEDs can also be used in the second emission section 4 and the dome-shaped illumination section 6.

[0071] The aforementioned shooting device 2 and inspection device 1 are capable of various transformations.

[0072] In the imaging device 2, for example, the optical axis J1 from the X-prism 5 toward the imaging area 90 of the printed circuit board 9 can be set at an angle relative to the vertical direction. In this case, the fluorescence generated in the imaging area 90 and the reflected light of the second emitted light in the imaging area 90 can be guided to the imaging unit 7 without passing through the X-prism 5. Thus, the imaging device 2 is not limited to coaxial incident illumination. Furthermore, in Figure 1 In the imaging device 2, for example, the configuration of the imaging unit 7 and the second emission unit 4 can be changed. In this case, in the X-ray prism 5, the direction towards... Figure 1 The upper surface of the lens is the second side surface 52, and the surface facing the right is the fourth side surface 54. In this way, the arrangement of the first emission section 3, the second emission section 4, and the imaging section 7 relative to the X-ray prism 5 can be appropriately changed.

[0073] In the imaging device 2, first emitted light and second emitted light can be emitted simultaneously from the first emission section 3 and the second emission section 4. In this case, for example, an optical element (such as a dichroic mirror) that separates the second emitted light and fluorescence can be provided in the imaging section 7, and the reflected light image and fluorescence image can be acquired simultaneously using the two imaging elements.

[0074] A transparent member can be provided in the opening 610 of the dome body 61 of the dome-shaped illumination unit 6, which allows light in the wavelength range of the first emitted light, the second emitted light, and fluorescence to pass through. In the imaging device 2 that includes the dome-shaped illumination unit 6, it is sufficient to provide a light-transmitting part in the dome body 61 that allows the first emitted light, the second emitted light, and fluorescence to pass through.

[0075] Based on the design of the dome-shaped lighting unit 6, a plurality of light sources can be provided on the inner surface 611 of the dome. Depending on the object to be photographed by the shooting device 2, the dome-shaped lighting unit 6 may be omitted.

[0076] A moving mechanism can be set up, with a fixed stage 21, which can move the first ejection section 3, the second ejection section 4, the X-prism 5, the dome-shaped lighting section 6 and the imaging section 7 as a whole.

[0077] The object of the imaging device 2 can be any object that fluoresces when irradiated by ultraviolet light, or it can be an object other than the printed circuit board 9.

[0078] The structures of the above-described embodiments and their variations can be appropriately combined as long as they do not contradict each other.

[0079] While the invention has been described and illustrated in detail, the above description is exemplary and not restrictive. Therefore, various modifications or methods are possible without departing from the scope of the invention.

Claims

1. A photographing device for photographing an object, wherein, The imaging device has: A stage to hold the object; The first emission section emits ultraviolet light, which is the first emitted light. The second emission section emits light with a wavelength range different from that of ultraviolet light, which is the second emitted light. A cross-shaped dichroic prism is a quadrangular prism with first to fourth side faces. Light emitted from the third side face, incident on the first side face, is directed to a shooting area on the object. Light emitted from the third side face, incident on the second side face, is also directed to the shooting area. The imaging unit receives fluorescence generated in the imaging area when the first emitted light illuminates the imaging area, and receives reflected light from the second emitted light in the imaging area when the second emitted light illuminates the imaging area.

2. The shooting device according to claim 1, wherein, The cross-shaped dichroic prism has a first mirror film and a second mirror film that intersect each other. The first mirror reflects the first emitted light and transmits the second emitted light. The second mirror film transmits the first emitted light, and reflects and transmits both the second emitted light and the fluorescence. Light from the shooting area is incident on the third side of the cross-shaped dichroic prism. A portion of the light is emitted from the fourth side of the cross-shaped dichroic prism and guided to the imaging unit.

3. The shooting device according to claim 2, wherein, In the cross-shaped dichroic prism, the first side face is opposite to the second side face, and the third side face is opposite to the fourth side face.

4. The shooting device according to claim 1, wherein, The imaging unit has a line sensor as the imaging element. The cross-shaped dichroic prism is a long strip along the direction of the first to fourth side surfaces.

5. The shooting device according to claim 1, wherein, The light source of the first emission section is a laser diode.

6. The shooting device according to claim 1, wherein, The shooting device further includes: a dome-shaped illumination section disposed on the optical axis between the third side surface of the cross-shaped dichroic prism and the shooting area, illuminating the shooting area from the dome-shaped surface covering the shooting area, and a light-transmitting section provided on the surface intersecting the optical axis.

7. The imaging device according to claim 1, wherein, The object being referred to is a printed circuit board.

8. An inspection device, wherein, have: The imaging device according to any one of claims 1 to 7; and The inspection department examines the images acquired using the aforementioned imaging device.

Images