Lens, optical system, imaging device, and inspection device

Abstract

The lens (43) of this disclosure focuses light so that it is incident on an object (14) on a first axis (21) at a predetermined incident angle (θ). It includes an incident surface (61), a reflecting surface (62), and an exit surface (63). Light is incident on the incident surface (61), the reflecting surface (62) reflects the incident light, and the exit surface (63) allows the light reflected by the reflecting surface (62) to exit. At least one of the incident surface (61), the reflecting surface (62), and the exit surface (63) has a shape that focuses light diffused circumferentially around a circle centered on the first axis (21). The reflecting surface (62) has a shape that focuses light diffused radially around the circle.

Description

Technical Field

[0001] This disclosure relates to lenses, optical systems, imaging devices, and inspection devices. Background Technology

[0002] As a dark-field observation illumination for observing scattered light, there is an illumination device as described in Patent Document 1.

[0003] Patent document 1, especially Figure 1 and Figure 3 The lighting device shown includes a substrate 16 arranged opposite to the object being illuminated and having a central hole 16a. On the substrate 16, an illuminator is provided with an array of light-emitting elements 15a-15c, which consists of multiple LEDs 14aa-14ch arranged in a ring around the hole 16a. Furthermore, an illumination control unit is included to selectively control each LED in any emission mode. With this structure, the illumination conditions of the illuminator can be precisely set according to the object being observed.

[0004] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 4-241476 Summary of the Invention

[0005] -The technical problem the invention aims to solve- Consider using the apparatus of Patent Document 1 to photograph a multilayer substrate with two reflective surfaces having different diffusion characteristics. When photographing with high contrast for high-precision inspection, it is necessary to photograph the scattered light from the two different reflective surfaces. The amount of scattered light depends on the diffusion characteristics of each reflective surface and the angle of incidence. Therefore, when photographing a multilayer substrate, there exists an angle of incidence where the contrast is maximized. Thus, to photograph with high contrast, it is desirable to illuminate the multilayer substrate from the LED lamp at an optimal angle of incidence.

[0006] However, if only LEDs with the optimal angle of incidence are selected to emit light when the optimal angle of incidence is large, the amount of light illuminating the object will be reduced. As a result, the image becomes darker and visibility deteriorates.

[0007] Generally speaking, the brightness of LED lights is insufficient, and the number that can be placed in a device is also limited. As a result, in order to capture bright images, LED lights with suboptimal illumination angles in terms of contrast are required, which leads to reduced contrast in the captured images.

[0008] This makes it difficult to balance high contrast and brightness in the captured images.

[0009] This disclosure provides lenses, optical systems, imaging devices, and inspection devices that balance high contrast and brightness when inspecting or photographing objects.

[0010] - Technical solutions used to solve technical problems - The lens disclosed herein focuses light so that it is incident at a predetermined incident angle θ onto an object on a first axis. It includes an incident surface, a reflecting surface, and an exiting surface. Light is incident on the incident surface, the reflecting surface reflects the incident light, and the exiting surface allows the reflected light to exit. At least one of the incident surface, reflecting surface, and exiting surface has a shape that focuses light diffused circumferentially in a circle centered on the first axis. The reflecting surface has a shape that focuses light diffused radially in a circle.

[0011] The optical system disclosed herein includes a lens and a plurality of light-emitting elements arranged around a first axis. The light-emitting elements cause light to be incident on the incident surface of the lens.

[0012] The imaging device disclosed herein includes an optical system and an objective lens, an imaging lens, and an imaging element arranged sequentially along a first axis from one side of the object. The lens focuses light emitted from the light-emitting element onto the object at an incident angle θ. The objective lens, imaging lens, and imaging element are used to capture the diffused reflected light diffused by the object.

[0013] The inspection apparatus disclosed herein includes a camera device, a control device for controlling the camera device, and a display device for displaying images captured by the camera device.

[0014] Another imaging device disclosed herein includes a plurality of light-emitting elements arranged around a first axis, a plurality of transmissive lenses respectively arranged between the plurality of light-emitting elements and an object on the first axis, and an objective lens, an imaging lens, and an imaging element arranged sequentially on the first axis from one side of the object. The light-emitting elements are arranged such that their optical axes are at a predetermined incident angle θ relative to the object. The transmissive lenses focus the light emitted from the light-emitting elements onto the object. The objective lens, the imaging lens, and the imaging element are used to capture images of the diffused reflected light diffused by the object.

[0015] Another imaging device disclosed herein includes a plurality of light-emitting elements arranged around a first axis, a reflector having a surface whose shape is formed by rotating a portion of an elliptic curve about the first axis as a reflective surface, and an objective lens, an imaging lens, and an imaging element arranged sequentially on the first axis from one side of the object. The reflector reflects light emitted from the light-emitting elements, causing it to enter the object at a predetermined incident angle θ and be focused. The objective lens, imaging lens, and imaging element are used to capture the diffused reflected light diffused by the object.

[0016] -The effects of the invention- The lens, optical system, camera device, and inspection device disclosed herein can achieve both high contrast and brightness when inspecting or photographing an object. Attached Figure Description

[0017] Figure 1 This is a schematic front view of an exemplary camera device according to a first embodiment of the present disclosure.

[0018] Figure 2 It is shown schematically. Figure 1 A bottom view of the LEDs and lenses in the camera device.

[0019] Figure 3 It is a schematic diagram showing a cross-section of a multilayer substrate that is being photographed and inspected, and its reflection of light.

[0020] Figure 4 This diagram illustrates the reflection characteristics of the electrode portion and the background portion of a multilayer substrate.

[0021] Figure 5 This is a diagram showing the relationship between the incident angle and the amount of light diffused in the vertical direction for the electrode portion and the background portion of a multilayer substrate.

[0022] Figure 6 This is a graph showing the relationship between the incident angle and contrast of a multilayer substrate.

[0023] Figure 7 This is a schematic front view of a camera device, showing a variation of the first embodiment.

[0024] Figure 8 This is a schematic front view of an exemplary camera device according to a second embodiment of the present disclosure.

[0025] Figure 9 It is shown schematically. Figure 8 The front view of the LEDs and lenses in the camera device.

[0026] Figure 10 It is shown schematically. Figure 8 A top view of the LEDs and lenses in the camera device.

[0027] Figure 11 It is shown schematically. Figure 8 A cross-sectional view of the LEDs and lenses in the camera device.

[0028] Figure 12 This is a diagram illustrating a simulated structure of the lighting system in the camera device of a comparative example.

[0029] Figure 13 It is a schematic top view showing the multilayer substrate as the subject of the photograph.

[0030] Figure 14 This is a diagram showing the structure of an inspection apparatus that includes the camera device disclosed herein.

[0031] Figure 15 This is a flowchart illustrating the operation of the inspection apparatus of this disclosure.

[0032] Figure 16 This is a schematic front view of the camera device of Modified Example 1 of the second embodiment.

[0033] Figure 17 It is shown schematically. Figure 16 A top view of the LEDs and reflectors in the camera device.

[0034] Figure 18 This is a schematic top view of the LED and lens in a variation of the second embodiment, Example 2.

[0035] Figure 19 This is a schematic cross-sectional view of the LED and lens in a variation 3 of the second embodiment.

[0036] Figure 20 This is a schematic front view of the camera device in Variation 4 of the second embodiment.

[0037] Figure 21 This is a schematic front view of the LED and lens in a variation 5 of the second embodiment.

[0038] Figure 22 This is a schematic cross-sectional view of the LED and lens in a variation 5 of the second embodiment.

[0039] Figure 23 This is a schematic front view of the LED and lens in a variation of the second embodiment, Example 6.

[0040] Figure 24 This is a schematic cross-sectional view of the LED and lens in a variation of the second embodiment, Example 6. Detailed Implementation

[0041] The embodiments will now be described based on the accompanying drawings. In the drawings, descriptions may be omitted by labeling the same components with the same symbols.

[0042] (First Implementation) Figure 1An exemplary imaging device 100 according to the first embodiment of this disclosure is schematically shown in a front view. The imaging device 100 uses an objective lens 15, an imaging lens 16, and an imaging element 17 to photograph a multilayer substrate 14, which is the object of the photograph. The multilayer substrate 14, objective lens 15, imaging lens 16, and imaging element 17 are arranged in this order on a first axis 21. It should be noted that the X, Y, and Z directions (axes) are shown in the figure. Figure 1 In the diagram, the side parallel to the first axis 21 and extending from the multilayer substrate 14 towards the image sensor 17 (vertically upward in the figure) is the positive side of the Z-axis. The X-axis is defined as the positive side on the right side of the figure, and the Y-axis is defined as the positive side on the inside side perpendicular to the paper. Figure 2 The X, Y, and Z directions are also shown in the subsequent diagrams.

[0043] In addition, it includes multiple projectile-shaped LEDs 11 and multiple transmissive lenses 13 respectively arranged between the projectile-shaped LEDs 11 and the multilayer substrate 14, which are used to illuminate the multilayer substrate 14 during shooting.

[0044] By using such an imaging device to photograph 100 objects (e.g., multilayer substrate 14), both high contrast and brightness can be achieved. For illustration, see [reference needed]. Figures 3-6 This demonstrates that when photographing the multilayer substrate 14, allowing light to be incident at an appropriate angle can improve contrast.

[0045] Figure 3 A cross-sectional view of a multilayer substrate 14 is shown. The multilayer substrate 14 has two or more reflective surfaces with different diffusion characteristics, and here it is provided with an electrode portion 31 and a background portion 32.

[0046] Figure 4 Figure A schematically illustrates the reflection and diffusion characteristics of light 33 when it is incident on electrode 31. At electrode 31, light 33 tends to diffuse in all directions. Therefore, along with the reflected light 35a in the specular reflection direction, the amount of diffused light 34a in the vertical direction is relatively large. The relationship between the incident angle θ and the diffused light 34a in the vertical direction in this case is... Figure 5 As shown in A. In the case of electrode section 31, the amount of diffused light 34a in the vertical direction is proportional to the amount of incident light, so as the incident angle θ increases, the amount of diffused light 34a in the vertical direction decreases linearly.

[0047] In contrast, Figure 4Figure B schematically illustrates the reflection and diffusion characteristics of light 33 when it is incident on the background portion 32. In the background portion 32, light 33 tends to be strongly reflected in the specular reflection direction, and the reflected light 35b in the specular reflection direction becomes stronger. However, since diffusion occurs, there is also diffused light 34b in the vertical direction. The relationship between the incident angle θ and the diffused light 34b in the vertical direction in this case is... Figure 5 As shown in section B. In the case of background section 32, as the incident angle θ increases, the diffused light 34b in the vertical direction decreases more sharply than in the case of electrode section 31, and then the decrease becomes gradual.

[0048] As a result, when light is incident on both the electrode portion 31 and the background portion 32 at the same incident angle θ, the contrast will differ depending on the angle θ. This is evident in... Figure 6 As shown in the diagram. The contrast ratio is obtained by dividing the amount of diffused light 34a in the vertical direction of the electrode portion 31 by the amount of diffused light 34b in the vertical direction of the background portion 32. Since... Figure 5 The dependence of the diffused light amount shown in A and B on the incident angle θ differs, thus the contrast reaches its maximum value. Therefore, by selecting the optimal incident angle θ, the contrast can be maximized. A preferred incident angle θ is 40° or more and 80° or less, more preferably 50° or more and 65° or less. As a more specific example, the contrast between the electrode portion 31 and the background portion 32 reaches its maximum when the incident angle θ is 57°. However, since the optimal incident angle θ varies depending on the subject being photographed, the material of the two portions such as the electrode portion 31 and the background portion 32, and their surface conditions, it is preferable to pre-measure the optimal incident angle θ.

[0049] Based on the above, the image obtained by the camera device 100 of this embodiment, which balances high contrast and brightness, will be described.

[0050] like Figure 2 As shown in the bottom view, a plurality of bullet-shaped LEDs 11 are disposed on the illumination substrate 12 and arranged around the first axis 21. In this embodiment, the illumination substrate 12 is annular. Furthermore, the bullet-shaped LEDs 11 emit light in a manner that diverges to a certain extent around the optical axis 24 with the maximum light intensity (radiated light 22). Such bullet-shaped LEDs 11 are disposed on the illumination substrate 12 with the incident angle of the optical axis 24 being the optimal incident angle θ (e.g., 57°) for the highest contrast as described above.

[0051] The emitted light 22 from each projectile-shaped LED 11 is incident on the corresponding transmissive lens 13. The light is focused by the transmissive lens 13 and incident on the multilayer substrate 14 at an optimal incident angle θ or close to that optimal incident angle. In this way, the incident light diffuses while exhibiting different diffusion characteristics in the electrode section 31 and the background section 32. The diffused light 34a and diffused light 34b in their respective vertical directions are imaged on the imaging element 17 through the objective lens 15 and the imaging lens 16. By setting the incident angle θ to an appropriate value, the contrast between diffused light 34a and diffused light 34b becomes high, thus enabling the capture of a high-contrast image.

[0052] It should be noted that the objective lens 15 is positioned at a focal length distance from the multilayer substrate 14, which is the object of the image. The imaging element 17 is positioned at a focal length distance from the imaging lens 16.

[0053] The transmissive lens 13 is preferably made of optical glass or resin. Furthermore, one transmissive lens 13 is disposed between each projectile-shaped LED 11 and the multilayer substrate 14. More specifically, the transmissive lens 13 is positioned such that the light-emitting chip surface of the projectile-shaped LED 11 is imaged on the multilayer substrate 14. Additionally, the focal length of the transmissive lens 13 can be determined based on the magnification of the imaging system composed of the objective lens 15 and the imaging lens 16, and the light-receiving range of the imaging element 17. For example, if the light-receiving range of the imaging element 17 is 10 mm square and the magnification of the imaging system is 20x, the focal length and position of the transmissive lens 13 can be set such that the chip surface of the projectile-shaped LED 11 is imaged in a size of 0.5 mm square.

[0054] Furthermore, it is preferable to arrange the transmissive lens 13 at an angle relative to the projectile-shaped LED 11 and the multilayer substrate 14, which serves as the imaging surface, such that the chip surface of the projectile-shaped LED, the surface of the multilayer substrate, and the main surface of the transmissive lens 13 intersect on the same straight line, thus satisfying Scheimpflug's principle. As a result, light radiated from the projectile-shaped LED 11 that previously could not be utilized, diffusing outward along the optical axis 24, can now be focused onto the multilayer substrate 14. Consequently, the amount of light incident on the multilayer substrate 14 increases, thereby improving image brightness. It should be noted that when the radiated light from the projectile-shaped LED 11 along its optical axis is incident on the multilayer substrate 14 at the optimal incident angle θ, the light diffusing outward along the optical axis is incident on the multilayer substrate 14 at an angle slightly deviating from the optimal incident angle θ.

[0055] Based on the above, by using a number of projectile-shaped LEDs 11 that can be arranged in the device, it is possible to capture high-contrast and bright images.

[0056] It should be noted that the above configuration is a structure in which the bullet-shaped LED 11 is arranged on the lighting substrate 12, but other structures can also be used. For example, a frame with multiple holes can be used to insert the bullet-shaped LED 11 into the holes and perform wiring.

[0057] There is no particular limitation on the wavelength of light emitted by the projectile-shaped LED11. Furthermore, multiple projectile-shaped LEDs11 do not need to all have the same wavelength. That is, multiple projectile-shaped LEDs11 with different wavelengths (emitting colors) can also be used.

[0058] Alternatively, an LED chip can be used instead of the projectile-type LED 11. In this case, a transmissive lens 13 or a prism can be arranged on the entire surface of the LED chip.

[0059] In addition, Figure 1 , Figure 2 The image shows an example where multiple transmissive lenses 13 are arranged independently. However, lenses with a structure that combines several or all of the adjacent transmissive lenses 13 can also be used.

[0060] Furthermore, the above description only illustrates an example of illumination using the combination of the projectile-type LED 11 and the transmissive lens 13, but is not limited to this. For example, it could also be as follows: Figure 7 Like the modified camera device 101 shown, it includes an incident illumination control unit 42 and a semi-reflective mirror 41. Here, other structures are similar to... Figure 1 Similarly, the semi-reflective mirror 41 can reflect light from the incident illumination control unit 42 and illuminate the multilayer substrate 14. By combining and controlling such light with light from the projectile-type LED 11, an easily identifiable image can be obtained.

[0061] Furthermore, although multilayer substrate 14 has been described as the subject of the photograph, it is not limited to this. Other subjects can also be bonding wires, IC pins, etc., which can also produce high-contrast and bright images in the same way as described above.

[0062] (Second Implementation) Next, the second embodiment of this disclosure will be described.

[0063] Figure 8 An exemplary imaging device 102 of this embodiment is schematically shown in a front view. Here, the multilayer substrate 14, objective lens 15, imaging lens 16, and imaging element 17, which are the objects of imaging, are shown in the front view. Figure 1 The camera device 100 is the same as that in this embodiment. In the camera device 102, instead of... Figure 1The system includes multiple transmissive lenses 13, including one lens 43. Additionally, the optical axis of the projectile-shaped LED 41 disposed on the illumination substrate 42 is parallel to the first axis 21 (in the -Z direction).

[0064] Figure 9 The lens 43, the bullet-shaped LED 41 disposed on the illumination substrate 42, and the multilayer substrate 14 are shown in more detail. Figure 10 Viewed from the 42 side of the lighting substrate Figure 9 A top view. Furthermore... Figure 11 Show along Figure 10 A cross-section cut along the XI-XI line.

[0065] In this embodiment, the illumination substrate 42 is arranged around and perpendicular to the first axis 21, with the first axis 21 as the center. The projectile-shaped LED 41 is disposed on the illumination substrate 42 with its optical axis parallel to the first axis 21. Therefore, the projectile-shaped LED 41 emits light in the -Z direction. This arrangement is useful for stabilizing the light emission direction and improving optical stability.

[0066] In addition, the projectile-shaped LEDs 41 are arranged at equal intervals on a circle centered on the first axis 21. It should be noted that this is a preferred arrangement, but not mandatory. Depending on the design requirements, projectile-shaped LEDs 41 arranged at different intervals from other positions or arranged off-center from the same circle may also be included.

[0067] In order to capture reflected light from the multilayer substrate 14 in the vertical direction, the illumination substrate 42 has a substrate center hole 67 in its central portion, and includes a partially cut-off portion for arranging the focus sensor 44 required for the alignment of the objective lens 15 during imaging, as shown in the top view ( Figure 10 In the substrate, the overall shape resembles the letter C. The central hole 67 of the substrate penetrates through the lighting substrate 42.

[0068] Light emitted from each of the projectile-shaped LEDs 41 is incident on the lens 43. The lens 43 includes an incident surface 61 for light incidence, a reflecting surface 62 for reflecting the incident light, and an exit surface 63 for emitting the reflected light. An edge portion 64 for holding the light is provided at the outermost periphery of the lens 43. Furthermore, the lens 43 includes a central aperture 68 for capturing reflected light from the multilayer substrate 14 in the vertical direction, and a portion of the lens being cut off to accommodate the focusing sensor 44, as shown in the top view (…). Figure 10 The lens 43 has a similar letter C shape to the illumination substrate 42. It should be noted that the defect is preferably formed by cutting off the lens 43 with a surface parallel to the first axis 21. This minimizes the impact of the defect on the function of the lens 43 when light is incident in the -Z direction. Furthermore, the lens center hole 68 penetrates the lens 43.

[0069] On the incident surface 61, identical cylindrical surfaces are arranged around the first axis 21 on a circumference, with adjacent cylindrical shapes connected at the intersection of the surfaces. The cylindrical shapes are arranged in a one-to-one correspondence with the projectile-shaped LED 41. Furthermore, the cylindrical shapes are designed for the diffused radiation 65 emitted from the projectile-shaped LED 41. Figure 9 This shape is preferred for focusing light that diffuses circumferentially around a circle centered on the first axis 21. However, the same effect can also be achieved with curved surfaces of other shapes.

[0070] Therefore, the utilization efficiency of the light emitted by the projectile-shaped LED 41 is improved, making the captured image brighter. In other words, when the incident surface 61 does not have a cylindrical shape, the light emitted by the projectile-shaped LED 41 that is diffusing off-axis is difficult to guide onto the multilayer substrate 14, making it inefficient for imaging. In contrast, the cylindrical shape of the incident surface 61 allows the radiated light 65 that diffuses circumferentially in the aforementioned circle to be focused and utilized.

[0071] It should be noted that in this embodiment, the cylindrical shapes are arranged on the same circumference; however, this is a preferred arrangement rather than a necessity.

[0072] Next, the light incident from the incident surface 61 is reflected by the reflecting surface 62 (total internal reflection). For example... Figure 11 As shown, the reflective surface 62 has a shape formed by rotating a portion of an ellipse around the first axis 21. The ellipse referred to here is an ellipse with two foci: the virtual point light source position coordinates P1 (x1, z1) calculated based on the light divergence angle of the projectile-type LED 41, and the center coordinates P0 (x0, z0) of the multilayer substrate 14.

[0073] By having such a shape for the reflective surface 62, the utilization efficiency of the light emitted by the projectile-shaped LED 41 is improved, and the captured image is also made brighter. In other words, because the cross-section of the reflective surface 62 is the aforementioned elliptical shape, therefore... Figure 11 In the cross-section shown, including the first axis 21, the radiated light 66 emitted from and diffused at the virtual point light source position coordinate P1 of the projectile-shaped LED 41 is focused at the center coordinate P0 by total internal reflection. This is equivalent to focusing the diffused light from the projectile-shaped LED 41 in the radial direction of a circle centered on the first axis 21.

[0074] As described above, by means of the cylindrical shape of the incident surface 61 and the reflective surface 62 having a shape formed by rotating a predetermined ellipse, it is possible to concentrate and utilize the light that was previously unusable diffusely emitted from the projectile-type LED 41.

[0075] It should be noted that the shape of the reflective surface 62 is designed such that the incident angle θ of light onto the multilayer substrate 14 is a preferred angle (e.g., 57°). Specifically, in Figure 11 In this design, the point where the line drawn from P1 in the -Z direction intersects the elliptic curve of the reflecting surface 62 is designated as the intersection point P2(x2, z2). The elliptic curve is designed such that the angle θ between the straight line P2P0 drawn from the intersection point P2 to the center coordinate P0 and the perpendicular line (first axis 21) from the center coordinate P0 along the Z direction is a preferred angle. Furthermore, the lens 43 is designed to increase the amount of light incident on the multilayer substrate 14 by adjusting the ratio of the major axis to the minor axis of the ellipse.

[0076] The light reflected from the reflective surface 62 exits through the exit surface 63 and reaches outside the lens 43. The exit surface 63 may also have a shape formed by rotating the arc around the first axis 21. As a result, the angle of the light emitted from the lens 43 can be adjusted, thereby improving the uniformity of illumination within the imaging range on the multilayer substrate 14 and enhancing the contrast.

[0077] Regarding this, it is assumed that the reflected light from the projectile-shaped LED 41 travels straight as before, as reflected by the reflective surface 62. In this case, the light along the optical axis is incident at an angle θ onto a point (center coordinate P0) on the multilayer substrate 14, while the diffused light, deviating from the optical axis, is incident at the same point at an angle deviating from the angle θ. In contrast, by designing the shape of the reflective surface 62, the focusing of the diffused light can be mitigated, bringing the angle of incidence closer to θ, and the incident position can be made to deviate from the center coordinate P0. Thus, the light from the projectile-shaped LED 41 can be incident at an angle close to the preferred angle of incidence θ, and diffused within the imaging range. It should be noted that, at this time, the design can be performed without affecting the light along the optical axis.

[0078] Light emitted from the exit surface 63 is incident on the multilayer substrate 14 at a preferred incident angle θ (e.g., 57°) or close to that angle and is diffused. The light diffused in the vertical direction (+Z direction) passes through the objective lens 15 and the imaging lens 16, and is imaged on the imaging element 17. This allows for the capture of high-contrast and bright images.

[0079] Table 1 shows the simulation results of brightness and contrast of images captured by the imaging device 102 of this embodiment and a conventional imaging device as a comparative example. Regarding the imaging device of the comparative example, in Figure 12The structure of the lighting system is shown in Figures A and B. In the comparative example of the imaging device, LEDs 111a, 111b, and 111c are arranged in three concentric rows inside the spherical substrate 110. The incident angles of the optical axes of the three rows of LEDs 111a, 111b, and 111c relative to the object 112 are 33°, 41.25°, and 49.5°, respectively, and the number of LEDs arranged are 16, 16, and 9, respectively.

[0080] In the camera device 102 of the second embodiment, there are 24 projectile-shaped LEDs 41.

[0081] [Table 1]

[0082] As shown in Table 1, in the camera device 102 of this embodiment, the contrast ratio is 1.7 times and the brightness is 2 times that of the comparative example. That is to say, although the number of LEDs in the camera device 102 is smaller, both the contrast ratio and the brightness are significantly higher than those of the comparative example.

[0083] Furthermore, although a portion of the projectile-shaped LED 41 and lens 43 were missing in the circumferential direction for the purpose of setting up the focus sensor 44, no deviation in illuminance distribution was observed as a result. This is because the illumination range of each projectile-shaped LED 41 is relatively wide compared to the shooting range, so even if a portion is missing, the impact on illuminance distribution is minimal. For the same reason, the reduction in light intensity caused by positional shift, rotational shift, or tilt of lens 43 is also minimal.

[0084] Furthermore, since the projectile-shaped LED 41 is arranged along the direction of the first axis 21 (Z-axis direction), and the focusing and incident angle are adjusted simultaneously through the lens 43, the device can be miniaturized in the X-axis and Y-axis directions.

[0085] As described above, light is irradiated from a projectile-shaped LED 41 arranged perpendicularly to the multilayer substrate 14, and then focused onto the multilayer substrate 14 by a lens 43 comprising an incident surface 61, a reflecting surface 62, and an exit surface 63. At this time, the light emitted from the projectile-shaped LED 41 reaches each surface in the order of incident surface 61, reflecting surface 62, and exit surface 63. Therefore, a large amount of light is irradiated onto the multilayer substrate 14 at an incident angle with increased contrast, enabling the capture of a high-contrast and bright image.

[0086] In this embodiment, the lens 43 is preferably made of optical glass or resin. Furthermore, at the reflecting surface 62, light is reflected according to the refractive index of the lens 43 and the angle of incidence of light relative to the reflecting surface 62. Metal deposition or similar processes can also be performed on the outer side of the reflecting surface 62. This makes the reflection at the reflecting surface 62 more reliable.

[0087] (Inspection device) Next, the inspection device using the camera device 102 of this embodiment will be described.

[0088] Figure 13 This is a schematic top view of the multilayer substrate 14, which is the object of imaging and inspection. Electrode sections 71 are provided on the multilayer substrate 14. Furthermore, a reference position O for imaging and inspection is defined in the electrode sections 71.

[0089] Figure 14 This diagram schematically illustrates an inspection apparatus for inspecting a multilayer substrate 14. The inspection apparatus includes a camera system 73, an XY stage 74, a Z stage 75, an imaging element 17, a control device 76, and a display device 77. The camera system 73 includes... Figure 8 The lens 43, illumination substrate 42, projectile-shaped LED 41, objective lens 15, and imaging lens 16 are included.

[0090] The multilayer substrate 14, which is to be inspected, is placed on the XY stage 74. The XY stage 74 is moved in the X and Y axes by the control device 76, thereby adjusting the position of the multilayer substrate 14 and the camera system 73. Similarly, the Z stage 75 is moved in the Z axis direction by the control device 76, thereby adjusting the position of the multilayer substrate 14 and the camera system 73.

[0091] The control device 76 controls the lighting and extinguishing of the projectile-shaped LED 41, as well as the light intensity. Furthermore, the camera element 17 is also controlled by the control device 76. The display device displays inspection-related information, including images captured by the camera element 17.

[0092] Figure 15 Showing through Figure 14 The flowchart illustrates the inspection process of the inspection device on the multilayer substrate 14. Here, the indentation inspection of the multilayer substrate 14 is taken as an example. All subsequent operations are performed by the control device 76.

[0093] First, confirm that the focus position of the image captured by the camera element 17 is correct. If correct, proceed to the next step; if incorrect, move the Z stage 75 in the Z direction and return to focus confirmation.

[0094] If the focus position is correct, the projectile-shaped LED 41 is illuminated. Next, the multilayer substrate 14 is photographed using the imaging element 17 and the imaging system 73 to obtain an inspection image. Then, based on the obtained inspection image, the position of the electrode section 71 is identified and a reference position O is obtained. Finally, the multilayer substrate 14 is moved using the XY stage 74 so that the reference position O becomes the reference position for indentation inspection.

[0095] Since the inspection apparatus of this embodiment includes the camera device 102 of this embodiment, it can acquire and use high-contrast and bright inspection images. As a result, the accuracy and efficiency of the inspection are improved.

[0096] It should be noted that the camera device 100 of the first embodiment and any camera device disclosed herein can be used to construct an inspection device in the same way.

[0097] (A variation of the second embodiment) Next, several variations of the camera device according to the second embodiment will be described.

[0098] (Variation Example 1) Figure 16 This is a schematic front view of the camera device 103 in Modified Example 1. Instead of... Figure 8 Lens 43 in the camera device 102, Figure 16 The camera device 103 includes a reflector 81. The reflector 81 includes an elliptical reflective surface 82, which has the same shape as the reflective surface 62 of the lens 43 and is coated with a reflective coating. Figure 17 A top view of the reflector 81, the illumination substrate 42, and the projectile-shaped LED 41 is shown.

[0099] By using such a reflector 81, light emitted from the projectile-shaped LED 41 can be focused onto the multilayer substrate 14 at a specified incident angle θ.

[0100] (Variation Example 2) in addition, Figure 18 A modified example 2 is shown regarding lens 43. In modified example 2, one or both of a stop hole 84 and a through hole 83 are included, the stop hole 84 being provided parallel to the first axis 21, and the through hole 83 being provided at the edge portion 64. Using such a stop hole 84 and through hole 83, it is possible to suppress rotational displacement of the lens, displacement in the X and Y directions, and is useful for suppressing light reduction, etc.

[0101] (Variation Example 3) in addition, Figure 19 A variation 3 is shown regarding lens 43. In variation 3, with... Figure 11 Compared to lens 43, the shape of the exit surface 63 is different. Specifically, in Figure 11 The cross-section of the exit surface 63 is arc-shaped, while... Figure 19 The cross-section of the exit surface 63 is a straight line (line segment). Therefore, in modified example 3, the exit surface 63 has a shape formed by rotating the line segment about the first axis 21. Thus, compared with... Figure 11Compared to the previous case, the incident angle and incident position of the light emitted from the exit surface 63 relative to the multilayer substrate 14 are different. This method can also be used to ensure that both the light on the optical axis and the light off the optical axis of the bullet-shaped LED 41 illuminate the imaging range on the multilayer substrate 14 at a preferred incident angle.

[0102] Similarly, regarding the shape of the reflecting surface 62, although it is stated that the cross-section is a defined ellipse, it is not limited to this. In particular, taking into account the shapes of the reflecting surface 62 and the exiting surface 63, and the refractive index of the lens material, the reflecting surface 62 may also be shaped by rotating a free-curve shape about the first axis 21. Regarding the shape of the exiting surface 63, it may also have a cross-section other than an arc or a line segment.

[0103] (Variation Example 4) in addition, Figure 20 The image device 104 shown is a modified example 4 that also includes a spot illumination control unit 42 and a semi-reflective mirror 41 for illumination. Other structures are similar to... Figure 8 The same as the camera device 102. By making the semi-reflective mirror 41 reflect the light from the incident illumination control unit 42 and illuminate the multilayer substrate 14, and combining it with the light from the projectile-type LED 41, more ideal lighting for shooting can be achieved.

[0104] (Variation Example 5) in addition, Figure 21 and Figure 22 Example 5 shows a variation of the lens. Figure 21 This is the front view of lens 43a in this modified example. Figure 22 It is along Figure 21 A cross-sectional view taken along line XXII-XXII. Lens 43a of this modified example is compared with... Figure 9 and Figure 10 Compared with lens 43, the shapes of the incident surface 61a and the reflecting surface 62a are different.

[0105] Figure 9 The incident surface 61 of lens 43 has a shape formed by an arrangement of cylindrical curved surfaces, which focuses light in the circumferential direction of a circle centered on the first axis 21. In contrast, the incident surface 61a of lens 43a in this modified example is planar and does not have the function of focusing light.

[0106] in addition, Figure 9 The reflective surface 62 of lens 43 is shaped by rotating a portion of an elliptic curve about the first axis 21. This concentrates light that diffuses radially in a circle centered on the first axis 21. In contrast, the reflective surface 62a of lens 43a in this modified example is shaped by arranging curved surfaces around the first axis 21, with one curved surface corresponding to one projectile-shaped LED 41. In a cross-section including the first axis 21, this shape is similar to... Figure 11 Similarly, it becomes a shape that focuses light diffused radially in a circle centered on the first axis 21. Additionally, in a cross-section perpendicular to the first axis 21 ( Figure 22 In this context, the shape becomes the one that focuses the light that diffuses circumferentially in a circle centered on the first axis 21.

[0107] Thus, in the lens 43a of this modified example, light is focused in both the circumferential and radial directions of the circle centered on the first axis 21 by the reflecting surface 62a. A lens 43a of this shape can also be used to efficiently utilize the light emitted from the projectile-type LED 41 (especially off-axis light). Furthermore, in the imaging device 103 of Modified Example 1 ( Figure 16 In the reflector 81 of the ), the elliptical reflector 82 can also be deformed to focus light in both the circumferential and radial directions of the circle centered on the first axis 21.

[0108] (Variation Example 6) in addition, Figure 23 and Figure 24 Example 6, a variation of the lens, is shown. Figure 23 This is the front view of lens 43b in this modified example. Figure 24 It is along Figure 23 A cross-sectional view taken along line XXIV-XXIV. Lens 43b of this modified example is compared with... Figure 9 and Figure 10 Comparing the lens 43, the shapes of the incident surface 61a and the exit surface 63a are different.

[0109] In this modified example of lens 43b, the incident surface 61a is a plane (and...). Figure 21 (The same as lens 43a). Additionally, the reflecting surface 62 is... Figure 9 Similarly, lens 43 focuses light that diffuses radially in a circle centered on the first axis 21. In contrast, the exit surface 63a has a shape that focuses light that diffuses circumferentially in a circle centered on the first axis 21. That is, the exit surface 63a is a shape formed by arranging curved surfaces on the circumference in such a way that one curved surface corresponds to one projectile-shaped LED 41.

[0110] Thus, in the lens 43b of this modified example, light is focused in both the circumferential and radial directions of the circle centered on the first axis 21 by the exit surface 63a. A lens 43a of this shape can also be used to efficiently utilize the light emitted from the projectile-type LED 41 (especially off-axis light).

[0111] Furthermore, regarding the second embodiment and its variations, an LED chip can be used instead of the projectile-type LED 41. In this case, a transmissive lens or prism can be arranged on the front surface of the LED chip. Additionally, with an LED chip, the light diffuses over a wider range compared to a projectile-type LED. Therefore, it is preferable to arrange the LED chip closer to the lens 43 than when using a projectile-type LED.

[0112] There is no particular limitation on the wavelength of light emitted by the projectile-shaped LED11. Furthermore, multiple projectile-shaped LEDs11 do not need to all have the same wavelength. That is, multiple projectile-shaped LEDs11 with different wavelengths (emitting colors) can also be used.

[0113] Furthermore, in the imaging and inspection apparatus of this embodiment, the lens 43 can be changed according to the object being photographed. That is, by using lenses with different shapes for at least one of the incident surface 61, the reflecting surface 62, and the exit surface 63, the illumination conditions, including the angle of incidence, can be optimized for different objects. As a result, high-contrast and bright images can be obtained for various objects.

[0114] Furthermore, in the example above, the projectile-shaped LEDs 41 are arranged in a circle, but they can also be arranged in two or more concentric circles. Additionally, the illumination of the projectile-shaped LEDs 41 can be selectively controlled. This allows for control based on the shape of the subject being photographed, enabling shooting with settings that provide good image recognition.

[0115] Furthermore, as described above, the optical axis of the bullet-shaped LED 41 is in the -Z direction and perpendicular to the incident surface 61 of the lens 43. This is preferred from the perspective of stabilizing the light emission direction. However, for other design reasons, the optical axis of the bullet-shaped LED 41 may be tilted away from the -Z axis direction.

[0116] In addition, in this embodiment, the object of photography is not limited to the multilayer substrate 14, but may also be bonding wires, IC pins, etc.

[0117] The embodiments described above are merely examples and are not intended to limit the scope of the claims. Furthermore, changes, combinations, and substitutions may be made to the embodiments and details without departing from the spirit and effectiveness of the claims.

[0118] -Industry Applicability- According to this disclosure, it is useful as a lens, optical system, imaging device, and inspection device, as it can achieve both high contrast and brightness in the captured image.

[0119] - Symbol Explanation - 11. Cannonball-shaped LEDs 12 lighting substrate 13 Transmission-type lenses 14 Multilayer substrate 15 Objective lenses 16 Imaging Lenses 17. Camera components 21 First Axis 22 radiant light 24 optical axes 31 Electrode section 32 Background Section 33 Light 34a Diffuse light (electrode section) 34b Diffuse light (background area) 35a Reflected light (electrode section) 35b Reflected light (background area) 41 Semi-reflective mirror 41. Cannonball-shaped LED 42 lighting substrate 42. Radiant Lighting Control Unit Lenses 43, 43a, and 43b 44 Focus Sensor 61, 61a Incident surfaces 62, 62a Reflecting surfaces 63, 63a Exit Surface 64 Edge 65 radiant light 66 radiant light 67. Center hole of substrate 68. Lens center hole 71 Electrode Section 73 Camera System 74 XY workbench 75 Z workbench 76 Control device 77 Display devices 81 Reflector 82 Elliptical Reflective Surface 83 Through Hole 84 Stop Hole 100-104 camera device 110 substrate 111a, 111b, 111c LED lights 112 Subjects

Claims

1. A lens that focuses light so that it is incident on an object on a first axis at a predetermined incident angle θ, characterized in that: Including the incident surface, the reflecting surface, and the exit surface. The light is incident on the incident surface. The reflective surface reflects the incident light. The exiting surface allows the light, after being reflected by the reflecting surface, to exit. At least one of the incident surface, the reflecting surface, and the exiting surface has a shape that focuses light diffused circumferentially in a circle centered on the first axis. The reflective surface has a shape that focuses light that diffuses radially in the circle.

2. The lens according to claim 1, characterized in that: The lens has a hole in the region containing the first axis.

3. The lens according to claim 1, characterized in that: The incident surface has a shape formed by arranging multiple identical curved surfaces around the first axis. The identical curved surfaces are cylindrical in shape.

4. The lens according to claim 1, characterized in that: The reflective surface has a shape formed by rotating a portion of an elliptical curve or a portion of a free curve about the first axis.

5. The lens according to claim 1, characterized in that: The incident angle θ is greater than 40° and less than 80°.

6. The lens according to claim 1, characterized in that: The exit surface has a surface formed by rotating a portion of the curve or line segment about the first axis, causing light to diffuse radially in a circle centered on the first axis.

7. The lens according to claim 1, characterized in that: The lens includes at least one of a stop hole and a through hole at a position different from the first axis.

8. The lens according to claim 1, characterized in that: The lens includes a defect formed by cutting out two planes parallel to the first axis.

9. An optical system, characterized in that: Includes the lens as described in claim 1, and a plurality of light-emitting elements arranged around the first axis. The light-emitting element causes light to be incident on the incident surface of the lens.

10. A camera device, characterized in that: Includes the optical system of claim 9, and an objective lens, an imaging lens, and an imaging element arranged sequentially on the first axis from one side of the object. The lens focuses the light emitted from the light-emitting element onto the object at the incident angle θ. The objective lens, the imaging lens, and the imaging element are used to capture the diffused reflected light diffused by the object.

11. An inspection device, characterized in that: It includes the camera device as described in claim 10, the control device for controlling the camera device, and the display device for displaying images captured by the camera device.

12. A camera device, characterized in that: It includes multiple light-emitting elements arranged around a first axis, multiple transmissive lenses respectively arranged between the multiple light-emitting elements and an object on the first axis, and an objective lens, an imaging lens, and an imaging element arranged sequentially on the first axis from one side of the object. The light-emitting elements are arranged such that the optical axis is at a predetermined incident angle θ relative to the object. The transmissive lens focuses the light emitted from the light-emitting element onto the object. The objective lens, the imaging lens, and the imaging element are used to capture the diffused reflected light diffused by the object.

13. The camera device according to claim 12, characterized in that: The incident angle θ is greater than 40° and less than 80°.

14. An inspection device, characterized in that: It includes the camera device as described in claim 12, the control device for controlling the camera device, and the display device for displaying images captured by the camera device.

15. A camera device, characterized in that: It includes multiple light-emitting elements arranged around a first axis, a reflector with a surface that is a shape formed by rotating a portion of an elliptical curve about the first axis as the reflector, and an objective lens, an imaging lens, and an imaging element arranged sequentially on the first axis from one side of the object. The reflector reflects the light emitted from the light-emitting element, directing it at a predetermined incident angle θ onto the object and focusing the light. The objective lens, the imaging lens, and the imaging element are used to capture the diffused reflected light diffused by the object.

16. The camera device according to claim 15, characterized in that: The incident angle θ is greater than 40° and less than 80°.

17. An inspection device, characterized in that: It includes the camera device as described in claim 15, the control device for controlling the camera device, and the display device for displaying images captured by the camera device.

Images