Imaging device

Abstract

The illumination unit, which includes a light source, a beam splitter, and an optical system, can be easily fixed to the dome-shaped illumination unit. [Solution] The first illumination unit 3 of the imaging device 2 is positioned on an optical axis J1 perpendicular to the imaging area 90 on the printed circuit board 9, and has an illumination unit body 31 with a dome-shaped inner surface 311 that covers the imaging area 90, and an opening 310 provided at a position on the inner surface 311 that intersects with the optical axis J1, and irradiates the imaging area 90 with first illumination light from the inner surface 311. The second illumination unit 4 is positioned on the opposite side from the printed circuit board 9 to the illumination unit body 31, and irradiates the imaging area 90 with second illumination light through the opening 310. On the illumination unit body 31, the surface on the second illumination unit 4 side is a support surface 316 perpendicular to the optical axis J1, and in the direction of the optical axis J1, the support surface 316 overlaps with the three-dimensional curved surface region 313 on the inner surface 311. The light source unit 41, beam splitter 43 and optical system 42 of the second illumination unit 4 are fixed to the support surface 316.

Description

Technical Field

[0004] ,

[0005] ,

[0001] The present invention relates to an imaging device for imaging an object.

Background Art

[0002] Conventionally, a device that adds dark-field illumination to coaxial epi-illumination (bright-field illumination) is known. For example, in the device of Patent Document 1, coaxial epi-illumination and dome-shaped illumination are used in combination. Usually, in an imaging device that uses coaxial epi-illumination and dome-shaped illumination in combination, a light source unit and a beam splitter for coaxial epi-illumination are arranged above the dome-shaped illumination unit having a dome-shaped outer shape (on the side opposite to the object). A part of the light from the light source unit is reflected downward (toward the object side) by the beam splitter and irradiates the object through an opening provided in the dome-shaped illumination unit. Further, an imaging unit is provided above the beam splitter, and the reflected light from the object enters the imaging unit through the beam splitter.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the imaging device as described above, for the purpose of efficiently using the light from the light source unit, etc., there may be a case where the epi-illumination light is shaped into a line beam, a spot light, a parallel light, etc. and irradiated onto the object. In this case, an optical system including a lens or the like is arranged between the light source unit and the beam splitter, but it is not easy to fix the light source unit, the beam splitter, and the optical system above the dome-shaped illumination unit having a dome-shaped outer shape.

[0005] This invention has been made in view of the above problems, and aims to easily fix an illumination unit having a light source, a beam splitter, and an optical system to a dome-shaped illumination unit. [Means for solving the problem]

[0006] One aspect of the present invention is an imaging device for imaging an object, comprising: a stage for holding the object; an illumination unit body positioned on an optical axis perpendicular to the imaging area on the object, having a dome-shaped inner surface that covers the imaging area and a light-transmitting section provided at a position on the inner surface that intersects the optical axis, and irradiating the imaging area with first illumination light from the inner surface; a second illumination unit positioned on the opposite side from the stage to the illumination unit body, and irradiating the imaging area with second illumination light through the light-transmitting section; and an imaging unit that receives reflected light from the imaging area that passes through the light-transmitting section along the optical axis with an image sensor, wherein the second illumination... The illumination unit comprises a light source unit that emits light, a beam splitter that guides a portion of the light from the light source unit to the light-transmitting unit as the second illumination light and guides a portion of the reflected light incident from the imaging area through the light-transmitting unit to the imaging unit, and an optical system disposed between the light source unit and the beam splitter for shaping the light from the light source unit. In the illumination unit body, the surface on the second illumination unit side is a support surface perpendicular to the optical axis, and in the direction of the optical axis, the support surface overlaps with at least a portion of the three-dimensional curved surface region on the inner surface, and the light source unit, the beam splitter and the optical system of the second illumination unit are fixed to the support surface.

[0007] Aspect 2 of the present invention is an imaging device according to aspect 1, wherein the external shape of the illumination unit body is cylindrical or prismatic.

[0008] A third aspect of the present invention is an imaging apparatus according to aspect 1 (or aspect 1 or 2), wherein the imaging unit has a line sensor as the image sensor, and the light source unit, the beam splitter, and the optical elements included in the optical system are elongated in the same direction.

[0009] Aspect 4 of the present invention is an imaging apparatus according to aspect 1 (which may be any one of aspects 1 to 3), wherein the imaging unit further comprises an imaging optical system that guides light from the beam splitter to the image sensor, and the illumination unit body is fixed to a lens barrel housing the imaging optical system via a support member.

[0010] Aspect 5 of the present invention is an imaging device according to any one of aspects 1 to 4, wherein the first illumination unit further has an annular channel through which a predetermined refrigerant flows around the entire circumference of the illumination unit body.

[0011] Aspect 6 of the present invention is an imaging apparatus according to aspect 5, wherein the first illumination unit further comprises an annular bottom surface portion extending radially inward and outward from the annular edge on the stage side of the inner surface of the illumination unit body, and a plurality of light sources arranged circumferentially on the surface of the annular bottom surface portion facing the inner surface, wherein the annular bottom surface portion closes the stage side of the annular flow path.

[0012] Aspect 7 of the present invention is an imaging device according to aspect 6, wherein the annular bottom portion is a metal substrate on which the plurality of light sources are mounted and on which wiring is formed. [Effects of the Invention]

[0013] According to the present invention, a second illumination unit having a light source, a beam splitter, and an optical system can be easily fixed to the illumination unit body. [Brief explanation of the drawing]

[0014] [Figure 1] This is a diagram showing the configuration of the inspection device. [Figure 2] This is a plan view showing the first and second lighting sections. [Figure 3] This figure shows an imaging device for a comparative example. [Figure 4] This is a diagram showing the captured image. [Figure 5] This is a diagram showing the captured image. [Figure 6] This figure shows another example of the first lighting unit. [Figure 7] This figure shows yet another example of the first lighting unit. [Modes for carrying out the invention]

[0015] Figure 1 shows the configuration of an inspection device 1 according to one embodiment of the present invention. The inspection device 1 in Figure 1 is an optical visual inspection device for inspecting the appearance of a printed circuit board 9. The inspection device 1 may be a device for inspecting substrates other than the printed circuit board 9, or a device for inspecting objects other than substrates. In Figure 1, three mutually orthogonal directions are indicated by arrows as the X, Y, and Z directions (the same applies to the figures described later). In the example shown in Figure 1, the X and Y directions are mutually perpendicular horizontal directions, and the Z direction is the vertical direction (i.e., up and down direction). Depending on the object being inspected by the inspection device 1, the Z direction may be a different direction from the vertical direction.

[0016] The inspection device 1 comprises an imaging device 2 and a computer 10. The computer 10 has a CPU and the like, and by executing a predetermined program, it realizes 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 the overall control of the inspection device 1. All or part of the inspection unit 11 and the control unit may be realized by dedicated electrical circuits.

[0017] The imaging device 2 includes a control unit, a stage 21, a stage moving mechanism 22, a first illumination unit 3, a second illumination unit 4, and an imaging unit 7. In the example of FIG. 1, the control unit of the inspection device 1 also serves as the control unit of the imaging device 2. The stage 21 holds the printed circuit board 9 that is the object to be imaged by the imaging device 2. In the example of FIG. 1, the printed circuit board 9 is supported and held by the stage 21 from below ((-Z) side). The printed circuit board 9 may be held on the stage 21 by suction adsorption or the like. The stage moving mechanism 22 has a motor, a ball screw, etc., and moves the stage 21. The moving directions of the stage 21 by the stage moving mechanism 22 are, for example, two directions (in FIG. 1, the X direction and the Y direction) along the main surface of the printed circuit board 9 and perpendicular to each other. The stage moving mechanism 22 may be a mechanism having a linear motor or the like.

[0018] FIG. 2 is a plan view showing the first illumination unit 3 and the second illumination unit 4 viewed from the (+Z) side in FIG. 1 toward the (-Z) direction. As shown in FIGS. 1 and FIG. 2, the second illumination unit 4 includes a beam splitter 43, a light source unit 41, and an optical system 42. The beam splitter 43 is disposed above the stage 21. The beam splitter 43 is, for example, a dichroic prism formed by bonding two right-angled prisms and has the outer shape of a quadrangular prism (in the example of FIG. 1, a regular quadrangular prism). A mirror film 44, which is a dielectric multilayer film, is formed on the interface of the two prisms. The mirror film 44 reflects and transmits the light from the light source unit 41.

[0019] The outer shape of the beam splitter 43 is long in the Y direction and has four side surfaces and two end surfaces. When the beam splitter 43 is viewed along the Y direction, the angle formed by the four side surfaces and the mirror film 44 is 45°. The side surface 431 on the (-Z) side of the beam splitter 43 faces the printed circuit board 9 on the stage 21 and is substantially parallel to the upper surface ((+Z) side surface) of the printed circuit board 9. As will be described later, in the second illumination unit 4, since optical elements other than the beam splitter 43 are also long in the Y direction, hereinafter, the Y direction is referred to as the "element longitudinal direction". The beam splitter 43 may be a cross-dichroic prism formed by bonding four right triangular prisms, or may be a plate-type beam splitter (half mirror) having a mirror film formed on a thin flat glass. As will be described later, since the light transmitted through the beam splitter 43 is guided to the imaging unit 7, in order to suppress the occurrence of ghosts in the acquired image, it is preferably that the beam splitter 43 is of a prism type.

[0020] The light source unit 41 emits, for example, visible light. The light emitted from the light source unit 41 may be light other than visible light. The light source unit 41 in the present embodiment includes a plurality of LEDs (light emitting diodes). The plurality of LEDs are arranged in the element longitudinal direction, and the light source unit 41 is long in the element longitudinal direction. A heat sink (cooling fins) is provided on the light source unit 41, and the heat sink is also long in the element longitudinal direction. In the light source unit 41, a light source other than an LED, such as a laser diode, may be used.

[0021] The optical system 42 guides light from the light source 41 to the beam splitter 43. The optical system 42 includes at least one optical element 421. In the example of Figure 1, the optical system 42 has a diffuser and a linear Fresnel lens as optical elements 421. Light emitted from the light source 41 is homogenized by these optical elements 421, and its light beam cross-section is shaped to extend in the longitudinal direction of the elements, and incident on the (+X) side surface 432 of the beam splitter 43. The optical elements 421 of the optical system 42 are also elongated in the longitudinal direction of the elements. The optical axis of the optical system 42 is perpendicular to the side surface 432 of the beam splitter 43. In this specification, when a plane (region) and the optical axis are perpendicular, this includes the case where they are substantially perpendicular (for example, within the range of 90°±5°, preferably within the range of 90°±3°).

[0022] A portion of the light incident from the optical system 42 to the beam splitter 43 passes through the mirror film 44, and the remaining portion is reflected by the mirror film 44. The light reflected by the mirror film 44 is emitted as second illumination light from the (-Z) side surface 431 of the beam splitter 43 and irradiates a region 90 (hereinafter referred to as the "imaging region 90") that extends in the longitudinal direction of the element on the upper surface of the printed circuit board 9. In this way, the second illumination unit 4 irradiates the imaging region 90 with second illumination light. As will be described later, the imaging region 90 is the region where imaging is performed by the imaging unit 7. Since specularly reflected light of the second illumination light is guided to the imaging unit 7, the second illumination light is light for specular illumination (bright-field illumination). In Figure 1, the optical axis between the side surface 431 of the beam splitter 43 and the printed circuit board 9 is denoted by the symbol J1. The optical axis J1 is perpendicular to the side surface 431 and the imaging region 90 of the printed circuit board 9, and runs along the vertical direction.

[0023] The first illumination unit 3 is positioned on the optical axis J1 between the side surface 431 of the beam splitter 43 and the imaging area 90. The first illumination unit 3 is a dome-shaped illumination unit and comprises an illumination unit body 31, a light source unit 32, an annular bottom surface 33, and a cooling structure 34. The external shape of the illumination unit body 31 is cylindrical with the optical axis J1 as its approximate center, and the outer circumferential surface of the illumination unit body 31 has a constant diameter along the optical axis J1. In other words, the outer edge of the cross-section perpendicular to the optical axis J1 (i.e., the cross-sectional shape of the outer circumferential surface) of the illumination unit body 31 has a constant shape along the optical axis J1. The external shape of the illumination unit body 31 may be prismatic. The illumination unit body 31 is formed from a metal such as aluminum, copper, or stainless steel.

[0024] The illumination unit body 31 has a dome-shaped (may be considered hemispherical or bowl-shaped) inner surface 311 (hereinafter referred to as "dome inner surface 311") that opens downwards. The dome inner surface 311 is the inner surface of a recess formed on the lower surface ((-Z) side surface) of the illumination unit body 31, and is a reflective surface. The dome inner surface 311 covers the imaging area 90 of the printed circuit board 9. An opening 310 is formed at a position on the dome inner surface 311 that intersects with the optical axis J1 (in the example of Figure 1, the upper part of the illumination unit body 31). The opening 310 is a light-transmitting part that allows light to pass through.

[0025] The dome surface 311 of the lighting unit body 31 includes a flat region 312 and a three-dimensional curved surface region 313. The flat region 312 is a flat region arranged around the opening 310 and perpendicular to the optical axis J1. The outer edge of the flat region 312 is, for example, circular. The three-dimensional curved surface region 313 is the region surrounding the flat region 312. The three-dimensional curved surface region 313 is a region of a curved surface that cannot be formed by deforming a plane (i.e., a curved surface that is not a developable surface), and in this embodiment, it is a region that is part of a substantially spherical surface. In Figure 2, the boundary between the flat region 312 and the three-dimensional curved surface region 313 is shown by a thin dashed line. The flat region 312 may be omitted from the dome surface 311.

[0026] The beam splitter 43 of the second illumination unit 4, as described above, is positioned near the top of the aperture 310. When viewed along the optical axis J1, the aperture 310 is the same size as most of the beam splitter 43 and, like the beam splitter 43, is elongated in the longitudinal direction (Y direction). The second illumination light emitted from the side surface 431 (see Figure 1) of the beam splitter 43 enters the illumination unit body 31 through the aperture 310 and irradiates the imaging area 90. As will be described later, the light source 41, optical system 42, and beam splitter 43 of the second illumination unit 4 are fixed to the illumination unit body 31.

[0027] The annular bottom portion 33 is attached to the lower end of the lighting unit body 31. The annular bottom portion 33 protrudes radially (radially inward and outward around the optical axis J1) from the annular edge on the stage 21 side of the dome inner surface 311 over its entire circumference. On the upper surface of the portion of the annular bottom portion 33 that protrudes radially inward, i.e., the upper surface of the portion facing the dome inner surface 311, a plurality of light sources (e.g., LEDs) 321 of the light source unit 32 are arranged circumferentially (circumferentially around the optical axis J1). In this embodiment, the annular bottom portion 33 is a metal substrate. An insulating layer is provided on the base material of the metal substrate, and a wiring pattern is formed on the insulating layer. A plurality of light sources 321 are mounted on this wiring pattern. The base material of the metal substrate is made of, for example, aluminum, copper, etc.

[0028] The light emitted from the light source 321 is in the same wavelength range as the second illumination light, for example, visible light. The light from the multiple light sources 321 is reflected (diffuse reflection or specular reflection) from the inner surface 311 of the dome and illuminates the imaging area 90. That is, the first illumination light is illuminated from the inner surface 311 of the dome to the imaging area 90 along various directions different from the optical axis J1. In this way, the first illumination unit 3 illuminates the imaging area 90 with the first illumination light for dark-field illumination. The cooling structure 34 will be described later.

[0029] The imaging unit 7 is positioned above the beam splitter 43 and comprises an image sensor 71, an imaging optical system 72, and a lens barrel 73. In this embodiment, the image sensor 71 is a line sensor. The line sensor extends in the longitudinal direction of the element. The imaging optical system 72 includes a plurality of lenses. The lens barrel 73 is substantially cylindrical and houses the imaging optical system 72. In the example in Figure 1, the imaging optical system 72 and lens barrel 73 are elongated in the vertical direction. On the outer circumferential surface of the lens barrel 73, one end of a vertically extending support member 51 is attached to the end on the beam splitter 43 side. The other end of the support member 51 is fixed to the outer circumferential surface of the illumination unit body 31. As a result, the illumination unit body 31 is supported by the imaging unit 7.

[0030] A portion of the reflected light from the first and second illumination beams illuminating the imaging area 90 passes through the aperture 310 along the optical axis J1 and enters the side surface 431 of the beam splitter 43. A portion of the reflected light that enters the beam splitter 43 is reflected by the mirror film 44 and heads towards the optical system 42, while another portion (the remainder) passes through the mirror film 44. The light that has passed through the mirror film 44 is emitted from the side of the beam splitter 43 on the imaging unit 7 side and enters the imaging optical system 72. The optical axis of the imaging optical system 72 is perpendicular to the said side surface of the beam splitter 43. The imaging optical system 72 forms an image of the imaging area 90 on the imaging surface of the image sensor 71. As a result, a line image representing the imaging area 90 is acquired. Note that an area sensor may be used as the image sensor 71 in the imaging unit 7.

[0031] In the image acquisition by the imaging device 2 in Figure 1, the stage movement mechanism 22 continuously moves the printed circuit board 9 in a direction perpendicular to the imaging area 90 (i.e., the X direction perpendicular to the longitudinal direction of the element). The image sensor 71 repeatedly acquires line images in parallel with the movement of the printed circuit board 9, thereby acquiring a two-dimensional multi-gradation image of the printed circuit board 9 (hereinafter referred to as the "imaging image"). In the inspection device 1 in this embodiment, the imaging image is acquired with the light emission from the first illumination unit 3 and the second illumination unit 4 turned ON. In the imaging device 2, since the illumination unit body 31 is provided between the printed circuit board 9 and the second illumination unit 4, stray light from the light source unit 41 is prevented from irradiating the imaging area 90 without providing a lens barrel in the second illumination unit 4.

[0032] Figure 3 shows an imaging device 8 of a comparative example. In the imaging device 8 of the comparative example, the first illumination unit 3 (dome-shaped illumination unit) in the imaging device 2 of Figure 1 is omitted, and multiple line illumination units 81 are arranged in an arc shape centered on the imaging area 90. Each line illumination unit 81 irradiates the imaging area 90 with illumination light whose light beam cross-section is long in the Y direction (elementary direction). As previously described, the line sensor of the imaging unit 82 is long in the Y direction.

[0033] Figure 4 shows an image acquired by the comparative example imaging device 8. In Figure 4, the X and Y directions are also shown in accordance with the printed circuit board 9 on the stage 21 (similarly in Figure 5 described later). The Y direction corresponds to the longitudinal direction of the line sensor and is also called the main scanning direction. The X direction is also called the sub-scanning direction. In the manufacturing of printed circuit boards, miniaturization is progressing, and in printed circuit boards manufactured by the SAP (Semi Additive Process) method, the surface of the conductive pattern becomes rounded. When acquiring an image of such a printed circuit board 9 with the comparative example imaging device 8, light is irradiated onto the imaging area 90 from directions inclined in both the X and Z directions on the XZ plane by multiple line illumination units 81. On the other hand, light is not irradiated onto the imaging area 90 from directions inclined in both the Y and Z directions on the YZ plane. As a result, in the image in Figure 4, for example, the line width in the Y direction of a pattern extending in the X direction becomes thinner or darker than it actually is.

[0034] In contrast, in the imaging device 2 shown in Figure 1, which uses a dome-shaped illumination unit, the first illumination unit 3, to perform dark-field illumination, light is irradiated onto the imaging area 90 from directions inclined in both the Y and Z directions on the YZ plane. As a result, as shown in Figure 5, the line width in the Y direction of patterns extending in the X direction in the captured image is prevented or suppressed from becoming thinner or darker than it actually is. In other words, imaging is performed under the same conditions for patterns extending in the X direction and patterns extending in the Y direction. As a result, the imaging device 2 can acquire a desirable image, and the inspection unit 11 can accurately inspect the printed circuit board 9.

[0035] Next, the fixing of the second illumination unit 4 to the illumination unit body 31 in the imaging device 2 of Figure 1 will be described. As previously mentioned, the illumination unit body 31 has a cylindrical shape except for its bottom surface. The top surface 316 of the illumination unit body 31 (the (+Z) side surface, hereinafter referred to as the "support surface 316") is perpendicular to the optical axis J1. As shown in Figure 2, the light source unit 41 of the second illumination unit 4 is fixed to the support surface 316 via, for example, a plate-shaped fixing member 61 extending in the longitudinal direction of the element (Y direction). The optical system 42 is fixed to the support surface 316 via, for example, fixing members 62 attached to both ends in the longitudinal direction of the element. The beam splitter 43 is fixed to the support surface 316 via, for example, fixing members 63 attached to both ends in the longitudinal direction of the element.

[0036] As shown in Figure 1, in the illumination unit body 31, the thickness between the three-dimensional curved region 313 of the dome inner surface 311 and the support surface 316 (thickness in the direction of the optical axis J1) is greater than the thickness between the flat region 312 and the support surface 316. In other words, in the illumination unit body 31, the area between the three-dimensional curved region 313 and the support surface 316 is a thick-walled portion, and the area between the flat region 312 and the support surface 316 is a thin-walled portion. In reality, the thickness between the three-dimensional curved region 313 and the support surface 316 (i.e., the thickness of the thick-walled portion) gradually increases towards the radially outward direction.

[0037] As shown in Figure 2, when viewed along the optical axis J1, the fixing members 61-63 are positioned on the support surface 316 in a region that overlaps with the three-dimensional curved region 313, i.e., on the thicker portion. This makes it possible to prevent any impact on the dome's inner surface 311 (for example, the tip of a screw protruding onto the dome's inner surface 311) even when the fixing members 61-63 are firmly fixed to the support surface 316 with screws or the like. Depending on the design of the imaging device 2, for example, the fixing member 63 that fixes the beam splitter 43 may be positioned on the thinner portion. The fixing of the light source unit 41, optical system 42, and beam splitter 43 to the support surface 316 can be carried out in various ways. For example, the light source unit 41, optical system 42, and beam splitter 43 may be directly fixed to the support surface 316 with screws, adhesive, or the like, without using the fixing members 61-63.

[0038] Next, the cooling structure 34 of the first lighting unit 3 will be described. As shown in Figures 1 and 2, the cooling structure 34 includes an annular flow path 35, a supply port 361, and a discharge port 362. The annular flow path 35 is a flow path through which a predetermined refrigerant flows, and is provided around the entire circumference of the lighting unit body 31. Here, the entire circumference includes the case of substantially the entire circumference, for example, a range of 300° or more in the circumferential direction, preferably a range of 330° or more. Except for the supply port 361 and the discharge port 362, the annular flow path 35 is sealed, and the printed circuit board 9 is not contaminated by the refrigerant. In the example of Figure 1, the annular flow path 35 is formed at the lower end of the outer circumferential surface of the lighting unit body 31. In detail, an annular channel 35 is formed by an annular plate portion 351 projecting radially outward from the outer circumferential surface of the lighting unit body 31, a cylindrical portion 352 hanging down (-Z) from the outer circumferential edge of the annular plate portion 351, and the aforementioned annular bottom portion 33 connected to the lower end of the cylindrical portion 352. A heat sink 342 projecting from the annular bottom portion 33 is provided within the annular channel 35. The heat sink 342 is arranged around the entire circumference.

[0039] As shown in Figure 2, the supply port 361 and the discharge port 362 are provided on the annular plate portion 351 and are adjacent to each other in the circumferential direction. In the annular flow path 35, a plate-shaped partition portion 353 is provided between the supply port 361 and the discharge port 362 in the circumferential direction to block the flow of fluid. The supply port 361 is close to one side of the partition portion 353, and the discharge port 362 is close to the other side. Coolant is supplied to the supply port 361 from the outside. In this embodiment, the coolant is compressed air. The coolant may be a gas other than compressed air, or a liquid such as water. The coolant flows through the annular flow path 35 from the supply port 361 to the discharge port 362 (see arrow A1 in Figure 2) and is discharged to the outside from the discharge port 362. This cools the lighting unit body 31, which is heated by the light from the light source 32. In addition, the annular bottom surface portion 33 is cooled via the heat sink 342. As described above, since the annular bottom portion 33 is a metal substrate, it is possible to efficiently cool the multiple light sources 321 on the annular bottom portion 33. The supply port 361 and discharge port 362 may be provided in the cylindrical portion 352 or the like.

[0040] As described above, the imaging device 2 in Figure 1 comprises a stage 21, a first illumination unit 3, a second illumination unit 4, and an imaging unit 7. The stage 21 holds the printed circuit board 9. The first illumination unit 3 is positioned on an optical axis J1 perpendicular to the imaging area 90 on the printed circuit board 9. The first illumination unit 3 has an illumination unit body 31 with a dome-shaped inner surface 311 (dome inner surface 311) that covers the imaging area 90, and an opening 310 provided on the inner surface 311 that intersects with the optical axis J1, and irradiates the imaging area 90 with first illumination light from the inner surface 311. The second illumination unit 4 is positioned on the opposite side of the stage 21 from the illumination unit body 31 and irradiates the imaging area 90 with second illumination light through the opening 310. The imaging unit 7 receives the reflected light from the imaging area 90 that passes through the opening 310 along the optical axis J1 with an image sensor 71. Furthermore, the second illumination unit 4 comprises a light source unit 41, a beam splitter 43, and an optical system 42. The beam splitter 43 guides a portion of the light from the light source unit 41 to the aperture 310 side as second illumination light, and also guides a portion of the reflected light incident from the imaging area 90 through the aperture 310 to the imaging unit 7. The optical system 42 is positioned between the light source unit 41 and the beam splitter 43 and shapes the light from the light source unit 41. As described with reference to Figure 5, the imaging device 2 having the first illumination unit 3 and the second illumination unit 4 can acquire a desirable image with suppressed line width thinning and the like.

[0041] Here, we consider a comparative example device in which the illumination unit has a dome-shaped exterior. In this comparative example device, since the illumination unit does not have a support surface (or has a narrow support surface), a dedicated mounting structure is required to attach the light source, beam splitter, and optical system of the second illumination unit to the illumination unit. In this case, in order to prevent the mounting structure from affecting the inner surface of the dome, for example, it is necessary to attach a mounting fixture to the lower end of the illumination unit and support the light source, etc. of the second illumination unit via a member extending upward from the mounting fixture. On the other hand, in the imaging unit, higher resolution is required, and the distance between the imaging unit and the printed circuit board (working distance: WD) tends to be shorter. From this viewpoint, attaching a mounting fixture to the lower end of the illumination unit is undesirable.

[0042] In contrast, in the imaging device 2 of Figure 1, the surface of the illumination unit body 31 facing the second illumination unit 4 is a support surface 316 perpendicular to the optical axis J1, and in the direction of the optical axis J1, the support surface 316 overlaps with the three-dimensional curved surface region 313 on the inner surface 311. The light source unit 41, beam splitter 43, and optical system 42 of the second illumination unit 4 are fixed to this support surface 316. This allows the second illumination unit 4 to be easily fixed to the illumination unit body 31 without attaching a mounting fixture to the lower end of the illumination unit body 31. Furthermore, in the illumination unit body 31, the heat capacity is increased by the thickened portion between the three-dimensional curved surface region 313 and the support surface 316. Therefore, even if excessively high heat is temporarily generated in the light source units 32 and 41, the presence of the thickened portion makes it possible to suppress the temperature rise in the light source units 32 and 41.

[0043] Preferably, the outer shape of the lighting unit body 31 is cylindrical or prismatic. This allows for a larger area of ​​the support surface 316 of the lighting unit body 31, making it easier to fix the second lighting unit 4.

[0044] Preferably, the imaging unit 7 has a line sensor as the image sensor 71, and the light source unit 41, beam splitter 43, and optical elements 421 included in the optical system 42 are elongated in the same direction. The illumination unit body 31 on which the support surface 316 is provided allows for easy fixing of the elongated light source unit 41, beam splitter 43, and optical elements 421.

[0045] Preferably, the imaging unit 7 further includes an imaging optical system 72 that guides light from the beam splitter 43 to the image sensor 71. The illumination unit body 31 is fixed to the lens barrel 73 that houses the imaging optical system 72 via a support member 51. This allows the illumination unit body 31 to be easily supported by the imaging unit 7.

[0046] Preferably, the first illumination unit 3 further has an annular channel 35 through which a predetermined refrigerant flows around the entire circumference of the illumination unit body 31. In the imaging device 2, the first illumination unit 3 is cooled by the refrigerant, and the second illumination unit 4 on the support surface 316 is also indirectly cooled via the illumination unit body 31. As a result, it is possible to suppress the occurrence of heat-related problems such as distortion of the captured image due to airflow within the illumination unit body 31, deformation of the components of the first illumination unit 3 and the second illumination unit 4, and deterioration of optical elements such as lenses.

[0047] Preferably, the first lighting unit 3 further includes an annular bottom surface portion 33 that extends radially inward and outward from the annular edge on the stage 21 side of the inner surface 311 of the lighting unit body 31, and a plurality of light sources 321 arranged circumferentially on the surface of the annular bottom surface portion 33 facing the inner surface 311. The annular bottom surface portion 33 closes the stage 21 side of the annular flow path 35, thereby efficiently cooling the plurality of light sources 321 via the annular bottom surface portion 33. Furthermore, if the annular bottom surface portion 33 is a metal substrate on which the plurality of light sources 321 are mounted and on which wiring is formed, the plurality of light sources 321 can be cooled more efficiently.

[0048] Figure 6 shows another example of the first illumination unit 3. The illumination unit body 31 in Figure 6 has an outer shape in which the upper part of the outer surface of the cylinder is tapered. The outer diameter of the support surface 316 on the second illumination unit 4 side is smaller than the outer diameter of the lower part of the illumination unit body 31. Even in this case, the support surface 316 extends radially outward so as to overlap a part of the three-dimensional curved surface region 313 on the inner surface 311 of the dome with the direction of the optical axis J1, making it possible to properly fix the light source 41, beam splitter 43, and optical system 42 of the second illumination unit 4 to the support surface 316. Thus, the support surface 316 of the illumination unit body 31 does not necessarily need to overlap with the entire three-dimensional curved surface region 313, but only needs to overlap with at least a part of the three-dimensional curved surface region 313.

[0049] Furthermore, in the lighting unit body 31 shown in Figure 6, the radial thickness of the annular lower end is relatively large, and an annular groove is formed on the lower end surface. The lower side of this groove is closed by the annular bottom surface 33, forming an annular flow path 35. The cooling structure 34 shown in Figure 6 also makes it possible to properly cool the lighting unit body 31, the multiple light sources 321, and the second lighting unit 4.

[0050] Figure 7 shows yet another example of the first illumination unit 3. In Figure 7, an annular bottom surface portion 33 is provided that extends radially inward from the annular lower end of the illumination unit body 31, and a light source substrate 320 on which multiple light sources 321 are mounted is attached to the upper surface of the annular bottom surface portion 33. The annular bottom surface portion 33 in Figure 7 is formed from, for example, the same material as the illumination unit body 31, and the base material of the light source substrate 320 is formed from, for example, resin. The light source substrate 320 may also be a metal substrate. In the example of Figure 7, the lower side of the annular flow path 35 is closed by an annular plate portion 354 that extends radially inward from the lower end of the cylindrical portion 352. In addition, a heat sink 342 is attached to the outer circumferential surface of the illumination unit body 31. The cooling structure 34 in Figure 7 also makes it possible to appropriately cool the illumination unit body 31, the multiple light sources 321, and the second illumination unit 4.

[0051] The imaging device 2 and inspection device 1 described above can be modified in various ways.

[0052] In the illumination unit body 31 of the first illumination unit 3, a transparent member that transmits light in the wavelength range of the first illumination light and the second illumination light may be provided in the opening 310. In the imaging device 2, the illumination unit body 31 may be provided with a light-transmitting section that transmits the first illumination light and the second illumination light (and their reflected light).

[0053] Depending on the design of the first lighting unit 3, multiple light sources may be provided on the inner surface 311 of the dome.

[0054] The cooling structure 34 of the first illumination unit 3 in the imaging device 2 may be used independently of the method for fixing the second illumination unit 4 on the support surface 316.

[0055] Depending on the object being imaged by the imaging device 2, a moving mechanism may be provided to move the first illumination unit 3, the second illumination unit 4, and the imaging unit 7 as a single unit.

[0056] The object to be imaged by the imaging device 2 may be something other than the printed circuit board 9.

[0057] The configurations in the above embodiments and each modified example may be combined as appropriate, as long as they do not contradict each other. [Explanation of Symbols]

[0058] 2. Imaging device 3. First Lighting Section 4. Second Lighting Section 7 Imaging Unit 9 Printed circuit boards 21 stages 31 Lighting Unit 33 Annular base 35 Circular channel 41 (Light source section of the second illumination unit) 42 Optical system (of the second illumination section) 43 Beam Splitter 51 Support member 71 Image sensor 72 Imaging Optical System 73 Telescope Tube 90 imaging area 310 Opening 311 Dome interior 313 3D curved area 316 Support surface 321 (Light source of the first illumination unit) 421 Optical element (of the second illumination section) J1 optical axis

Claims

1. An imaging device for imaging an object, A stage for holding the object, The illumination unit has an illumination unit body positioned on an optical axis perpendicular to the imaging area on the object, with a dome-shaped inner surface covering the imaging area, and a light-transmitting portion provided at a position on the inner surface intersecting the optical axis, and the first illumination unit irradiates the imaging area with first illumination light from the inner surface, A second illumination unit is positioned on the opposite side from the stage to the illumination unit body and irradiates the imaging area with second illumination light through the light-transmitting unit, An imaging unit that receives light from the imaging area that passes through the light-transmitting portion along the optical axis, using an image sensor, Equipped with, The second lighting unit, A light source that emits light, A beam splitter guides a portion of the light from the light source to the light-transmitting section as the second illumination light, and guides a portion of the reflected light incident from the imaging area through the light-transmitting section to the imaging section. An optical system is positioned between the light source and the beam splitter to shape the light from the light source, Equipped with, In the illumination unit body, the surface on the second illumination unit side is a support surface perpendicular to the optical axis, and in the direction of the optical axis, the support surface overlaps with at least a portion of the three-dimensional curved surface region on the inner surface. An imaging device in which the light source unit, beam splitter, and optical system of the second illumination unit are fixed to the support surface.

2. The imaging apparatus according to claim 1, An imaging device in which the external shape of the illumination unit body is cylindrical or prismatic.

3. The imaging apparatus according to claim 1, The imaging unit has a line sensor as the image sensor, An imaging device in which the light source, the beam splitter, and the optical elements included in the optical system are elongated in the same direction.

4. The imaging apparatus according to claim 1, The imaging unit further includes an imaging optical system that guides light from the beam splitter to the image sensor. An imaging device in which the illumination unit body is fixed to a lens barrel housing the imaging optical system via a support member.

5. An imaging device according to any one of claims 1 to 4, An imaging device wherein the first illumination unit further has an annular channel through which a predetermined refrigerant flows around the entire circumference of the illumination unit body.

6. The imaging apparatus according to claim 5, The first lighting unit, The annular bottom surface portion extending radially inward and outward from the annular edge on the stage side of the lighting unit body on the inner surface, Multiple light sources arranged circumferentially on the surface facing the inner surface of the annular bottom portion, It further possesses, An imaging device in which the annular bottom portion closes the stage side of the annular channel.

7. The imaging device according to claim 6, An imaging device in which the annular bottom portion is a metal substrate on which the plurality of light sources are mounted and on which wiring is formed.

Images