Optical inspection device and sorting device

Abstract

We provide an optical inspection device that is smaller than conventional devices. [Solution] The optical inspection apparatus 10 includes one or more line sensors 11 installed along a straight line W that intersects a virtual plane V containing the movement path U of the object to be inspected S; a first mirror group 12 that constitutes a first optical path B from the surface of the object to be inspected S moving along the movement path U to the line sensor 11, including a plurality of mirrors 13, 15, 16 arranged on one side perpendicular to the plane of the virtual plane V; a second mirror group 21 that constitutes a second optical path C from the back surface of the object to be inspected S moving along the movement path U to the line sensor 11, including a plurality of mirrors 13, 15, 16 arranged on the other side perpendicular to the plane of the virtual plane V; and two optical lens assemblies 14, 14, one of which are arranged in the first optical path B and the second optical path C, respectively.

Description

[Technical Field]

[0001] The present invention relates to an optical inspection device and a sorting device. [Background Art]

[0002] Conventionally, as a device for inspecting granular materials by light, for example, the granular material sorting devices described in Japanese Patent No. 4675120 (Patent Document 1) and Japanese Patent No. 7537078 (Patent Document 2) are known. In the granular material sorting devices described in Patent Document 1 and Patent Document 2, two light-receiving devices (line sensors such as CCDs and area sensors) are symmetrically arranged so as to form a pair with respect to the movement path of the granular material, and the front surface and the back surface of the granular material are imaged respectively.

[0003] In addition, the visual inspection apparatus described in Japanese Patent No. 6801860 (Patent Document 3) is configured such that half mirrors are arranged inclined on both sides with a small article such as a tablet as an object to be inspected interposed therebetween, parallel laser light emitted from a laser light irradiation means that transmits through the half mirrors is irradiated onto the object to be inspected, and the outer appearance of both side surfaces of the object to be inspected irradiated with the parallel laser light is imaged by an imaging means via the half mirrors. Accordingly, parallel laser light is respectively irradiated onto both side surfaces of a small article such as a tablet, the outer appearance of both side surfaces of the small article such as a tablet is imaged by one imaging means (CMOS camera), and foreign matter and defects are detected. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent No. 4675120 [Patent Document 2] Japanese Patent No. 7537078 [Patent Document 3] Japanese Patent No. 6801860 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] However, the inventors have found that there are areas for further improvement in the conventional inspection devices described above. Specifically, the granular material sorting devices described in Patent Documents 1 and 2 require two imaging devices in total, one on the front side and one on the back side of the object to be inspected, resulting in a large overall size for the inspection device section of the granular material sorting device. For the sake of portability as an inspection device and ease of installation in country elevators (large-scale drying, processing, and storage facilities), it is preferable for the inspection device section to be compact.

[0006] Furthermore, the imaging means (CMOS camera) of the visual inspection apparatus described in Patent Document 3 is unsuitable for photographing objects under inspection that move at relatively high speeds, such as granular materials that fall under their own weight. For this reason, it cannot be used in inspection apparatuses for country elevators where large quantities of granular materials (for example, continuously flowing grains) free-fall through channels such as chutes and troughs.

[0007] Furthermore, the visual inspection device described in Patent Document 3 simultaneously photographs the appearance of both sides of an object to be inspected by irradiating it with parallel laser light. Therefore, it excels at detecting defects (uneven shapes) in small items such as tablets, but is not good at determining whether an item is good or bad by color analysis of items without defects (uneven shapes).

[0008] In view of the above circumstances, the present invention aims to provide an optical inspection device that is smaller than conventional devices. [Means for solving the problem]

[0009] For this purpose, the optical inspection apparatus according to the present invention comprises: one or more optical line sensors installed along a straight line intersecting a virtual plane including the movement path of the object to be inspected; a first mirror group comprising a plurality of mirrors arranged in one direction perpendicular to the plane of the virtual plane and constituting a first optical path from the surface of the object to be inspected moving along the movement path to the optical line sensor; a second mirror group comprising a plurality of mirrors arranged in the other direction perpendicular to the plane of the virtual plane and constituting a second optical path from the back surface of the object to be inspected moving along the movement path to the optical line sensor; and two optical lens assemblies, one each arranged in the first and second optical paths, or one optical lens assembly arranged across both the first and second optical paths.

[0010] According to this invention, a single slender optical line sensor can simultaneously inspect both the front and back surfaces of an object under inspection. Therefore, the inspection device can be made smaller than conventional devices, resulting in cost advantages. One optical lens assembly may be placed in each of the first and second optical paths. Furthermore, if the optical paths between the line sensor and the mirror closest to the line sensor are close to each other, only one optical lens assembly spanning both the first and second optical paths may be used. Moreover, the number of mirrors in the first mirror group is not particularly limited. Increasing the number of mirrors allows for greater bending of the first optical path, increasing the flexibility of component layout. The same applies to the second mirror group.

[0011] In one aspect of the present invention, two optical lens assemblies are positioned between adjacent mirrors on a first optical path and between adjacent mirrors on a second optical path. In this aspect, the inspection device can be further miniaturized by positioning the optical lens assemblies between the mirrors.

[0012] Incidentally, when the surface of an object under inspection is photographed with the first mirror group and the back surface is photographed with the second mirror group, it is preferable to prevent the sensor area for photographing the back surface from being reflected in the sensor area for photographing the surface. Therefore, a preferred aspect of the present invention is the further provision of an adjustment means for adjusting at least one of the tilt angle and position of at least one mirror of the first mirror group and the second mirror group. According to this aspect, by adjusting the tilt angle and / or position of at least one mirror of the first mirror group and the second mirror group, at least one of the optical axis of the first optical path or the optical axis of the second optical path is tilted to the upstream or downstream side in the direction of movement of the object under inspection. This makes it possible to avoid the sensor area for photographing the back surface being reflected in the sensor area for photographing the surface. Furthermore, by adjusting the mirror tilt angle and / or position, the movement speed and flow rate of the object under inspection can be calculated. Note that the aforementioned "reflection of the sensor area for photographing the back surface in the sensor area for photographing the surface" may be referred to as "staring contest" below.

[0013] In a more preferred aspect of the present invention, the adjustment means includes a first operating unit for adjusting one mirror on a first optical path and a second operating unit for adjusting another mirror on the first optical path, and / or the adjustment means includes a first operating unit for adjusting one mirror on a second optical path and a second operating unit for adjusting another mirror on the second optical path. In one aspect of the present invention, the adjustment means includes a first operating unit for adjusting two mirrors on a first optical path and a second operating unit for adjusting either one of the two mirrors, and / or the adjustment means includes a first operating unit for adjusting two mirrors on a second optical path and a second operating unit for adjusting either one of the two mirrors. In a preferred aspect of the present invention, the adjustment means adjusts the tilt angle of the mirrors around an adjustment axis, wherein the adjustment axes of the two mirrors adjusted by the first operating unit and the adjustment axis of either mirror adjusted by the second operating unit are common axes.

[0014] The sorting apparatus of the present invention comprises the optical inspection apparatus described above and a discharge means for removing the object to be inspected from the movement path. According to the present invention, after optical inspection by the optical inspection apparatus, defective products (e.g., discolored particles) can be removed from the object to be inspected by the discharge means. The discharge means is not particularly limited, but for example, it is an ejector valve that sprays compressed air onto the object to be inspected to remove it from the movement path. [Effects of the Invention]

[0015] Thus, according to the present invention, the inspection device is smaller than conventional devices, improving portability and assembly. Furthermore, by stitching together images continuously captured at high speed by a line sensor, an overall image of multiple moving objects to be detected can be formed, contributing to high-precision inspection of the objects to be detected. In addition, since both sides of the object to be inspected can be captured with a single line sensor, it is more cost-effective than conventional methods. [Brief explanation of the drawing]

[0016] [Figure 1A] This is a schematic perspective view showing an optical inspection device according to one embodiment of the present invention. [Figure 1B] This is a perspective view showing the first and second adjustment means of the same embodiment. [Figure 1C] This is a perspective view showing the second adjustment means in the same embodiment. [Figure 2] This is a schematic plan view (top view) showing the optical path and optical axis of the embodiment. [Figure 3] This is a schematic perspective view showing the optical axis adjustment of the same embodiment. [Figure 4] This is a schematic diagram showing the optical axis of the same embodiment. [Figure 5] These are photographs of the surface (front) and back (rear) of the granular material (grain) taken by the same embodiment. [Figure 6] This is a schematic diagram showing the optical axis during shooting, where (a-1) to (a-3) represent a desirable state and (b) represents an undesirable state. [Figure 7] This is a schematic plan view (top view) showing an optical inspection apparatus according to another embodiment of the present invention. [Figure 8] It is a schematic plan view (top view) showing an optical inspection apparatus according to a modified example of the present invention. [Figure 9] It is a schematic plan view (top view) showing an optical inspection apparatus according to a modified example of the present invention. MODE FOR CARRYING OUT THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1A is a schematic perspective view showing an optical inspection apparatus according to an embodiment of the present invention. FIG. 2 is a schematic plan view (top view) showing an optical path and an optical axis of the embodiment. The optical inspection apparatus 10 includes a line sensor 11 capable of optically detecting light obtained by reflecting or transmitting light for side illumination indicated by reference numerals 33, 34, 35, and 36 in FIG. 4, a first mirror group 12, and a second mirror group 21. The line sensor 11 extends long from one side to the other side of the optical inspection apparatus 10 (hereinafter also referred to as the front-rear direction, front-rear, or front-back), and has a plurality of imaging elements. The imaging elements are composed of, for example, three rows of light-receiving elements corresponding to the three primary colors of visible light (RGB 3 line), and a large number of said rows are arranged along the longitudinal direction of the line sensor 11. Alternatively, the line sensor 11 may be a monochrome sensor formed of one row of light-receiving elements, or may be configured to use one or several rows of an area sensor. In addition to visible light, the line sensor 11 may also be a light-receiving sensor capable of optically detecting near-infrared light in a wavelength range longer than visible light, ultraviolet light in a wavelength range shorter than visible light, X-rays, etc., or may be a light-receiving sensor capable of optically detecting laser light.

[0018] The first mirror group 12 on the front side of the optical inspection device 10 (the direction of "front" in the coordinates of Figure 1A) is positioned corresponding to one end region of the line sensor 11. The second mirror group 21 on the rear side of the optical inspection device 10 (the direction of "rear" in the coordinates of Figure 1A) is positioned corresponding to the other end region of the line sensor 11. When a virtual plane V (which overlaps with the flat, thin plate ruler P in Figure 1A, and is shown as the dashed line VV in Figure 2) is set that intersects with the central part of the line sensor 11, the first mirror group 12 and the second mirror group 21 are positioned symmetrically or approximately symmetrically with respect to the virtual plane V. This virtual plane V is a reference plane that does not exist as a device component of the optical inspection device 10. A flat, rigid, strip-shaped ruler P (included in the virtual plane V in Figure 1A) can be detachably installed and fixed on this virtual plane V for the convenience of adjusting the tilt angles of the first mirror group 12 and the second mirror group 21, as described later. Note that the ruler P is removed from the optical inspection device 10 when inspecting the object to be inspected by the optical inspection device 10. Since the first mirror group 12 and the second mirror group 21 are individually adjusted inclination angles, they do not need to be strictly symmetrical with respect to the virtual plane V, but are only required to be approximately symmetrical. The line sensor 11 is positioned along a virtual straight line W (the dashed line W in Figure 1A, in the front-to-back direction of the coordinates in Figure 1A) that intersects the virtual plane V. In this embodiment, the virtual straight line W is perpendicular to the virtual plane V.

[0019] Next, the detailed internal structures of the first mirror group 12 and the second mirror group 21 will be described. To avoid repetition in the description, the first mirror group 12 will be described as representative. The first mirror group 12 includes a plurality of mirrors 13, 15, and 16, and an optical lens assembly 14 (see Figures 1A and 2). In this embodiment, the line sensor 11, mirror 13, optical lens assembly 14, mirror 15, mirror 16, and ruler P are arranged in that order, and the first optical path B, which will be described later, is formed between the line sensor 11 and ruler P. The optical lens assembly 14 has one or more lenses and a support such as an outer cylinder that supports the lenses.

[0020] In Figure 1A, the first optical path B, which is the path of light connecting one end region of the line sensor 11 to the object under inspection S, has an optical axis B2 defined, which is the path of light passing through the centers of the mirrors 13, 15, and 16 and the center of the optical lens assembly 14. With respect to optical axis B2, there is a field of view B1, which is one end of the field of view, and a field of view B3, which is the other end of the field of view. The first optical path B is the path of light for viewing the surface of the object under inspection S (hereinafter also referred to as the front). Similarly, the second optical path C of the second mirror group 21 also has an optical axis C2 and fields of view C1 and C3.

[0021] The first optical path B of the first mirror group 12 is either included in a virtual plane (not shown) that is perpendicular to the movement path U (virtual plane V) of the object S under inspection, or it is positioned at a slight inclination (0° to 10°) relative to that virtual plane.

[0022] The same applies to the second optical path C (see Figure 2), which is the optical path connecting the other end region of the line sensor 11 to the object under inspection S. The second optical path C is the optical path for viewing the back surface (hereinafter also referred to as the rear surface) of the object under inspection S. Note that the terms front and back (front and rear) used here are for convenience and can be rephrased as one side (surface) and the other side (surface) of the virtual plane V, or one side (surface) and the other side (surface).

[0023] The second optical path C of the second mirror group 21 is either included in a virtual plane (not shown) perpendicular to the movement path U (virtual plane V) of the object S under inspection, or it is positioned at a slight inclination (0° to 10°) relative to that virtual plane.

[0024] The first optical path B and the second optical path C are symmetrical or nearly symmetrical with respect to the virtual plane V. Nearly symmetrical means that, strictly speaking, a slight asymmetry can be observed between the first optical path B and the second optical path C due to the adjustment of the inclination angles of mirrors 13, 15, and 16, which will be described later.

[0025] Furthermore, the detailed structure will be described with reference to Figures 1A, 1B, and 1C. The optical inspection device 10 further includes a table-shaped support section 17 that supports multiple mirrors 15, 16 of the first mirror group 12, and an adjustment shaft X1 and a first operating section 19 as a first adjustment means for adjusting the inclination angle of the support section 17. The optical inspection device 10 also further includes a support section 37 that supports one mirror 16 of the first mirror group 12, and an adjustment shaft X2 and a second operating section 39 as a second adjustment means for adjusting the inclination angle of the support section 37. In addition, the optical inspection device 10 also further includes a support section 27, an adjustment shaft X3 and a first operating section 19 as a first adjustment means, a support section 37, and an adjustment shaft X4 and a second operating section 39 as a second adjustment means, similar to the first mirror group 12.

[0026] Between the mirror 16 of the first mirror group 12 and the mirror 16 of the second mirror group 21, a movement path U (Figure 1A) for the object to be inspected is set so as to pass through the same location where the ruler P is temporarily installed and fixed. The object to be inspected is a granular material such as grain, and specific examples of grains include rice grains, wheat grains, and corn grains, as well as threshed rice, hulled brown rice, polished white rice, beans, and other seeds. Furthermore, in addition to grains, it may also be a granular material made of pelletized resin material that is a raw material for resin products such as liquid crystal panels, other industrial products (granular materials), or natural products (granular materials) collected from nature. The movement path U (Figure 1A) extends vertically from top to bottom as indicated by the arrow. In short, the object to be inspected S is a multitude of granular objects that move by free-falling from the lower end of a chute or belt conveyor (not shown) located upstream of a virtual plane V (indicated as P(V) in Figure 1), or by being thrown out. Alternatively, the object to be inspected S may be transported on a transparent plate that moves along a movement path U. Furthermore, the object to be inspected S may be linear, such as thin noodles, or sheet-like, such as seaweed. The movement path U is included in the virtual plane V.

[0027] Figure 4 is a schematic diagram showing the optical axis of the embodiment, with the light-receiving element of the line sensor viewed from the front. Referring to Figures 2 and 4, when the movement path U is oriented vertically downward, the section b4 of the optical axis B2 of the first optical path B, which is closest to the object under inspection S (the section between the object under inspection S and the mirror 16 closest to the object under inspection S), is not strictly perpendicular to the movement path U (it is positioned at a slight inclination). The same applies to the section c4 of the optical axis C2 of the second optical path C, which is between the object under inspection S and the mirror 16 closest to the object under inspection.

[0028] Referring to Figure 4, a background 31 is installed behind the object S being inspected, b4', when viewed from section b4. The background 31 brightly illuminates the area behind section b4', b4'. Similarly, a background 32 is installed behind the object S being inspected, c4', when viewed from section c4.

[0029] Furthermore, illumination lights 33 and 35, such as LEDs or fluorescent lamps, are positioned above and / or below the first mirror group 12. The illumination lights 33 and 35 illuminate the surface (front) of the object S under inspection. The background 31 and the illumination lights 33 and 35 are positioned so as not to interfere with a virtual plane (not shown) that contains or is located near the first optical path B, on one side (above) and / or the other side (below) perpendicular to the plane. Similarly, illumination lights 34 and 36 are positioned for the second optical path C. The illumination lights 34 and 36 illuminate and clarify the back surface (rear) of the object S under inspection.

[0030] Figure 6 is a schematic diagram showing the optical axis when photographing an object under inspection, with Figures 6(a-1), 6(a-2), and 6(a-3) representing a preferred state and Figure 6(b) representing an undesirable state. In this embodiment, as shown in Figure 6(a-1), a section b4 of the optical axis B2 of the first optical path and a section c4 of the optical axis C2 of the second optical path are not on the same straight line (they are not facing each other). This allows backgrounds 31 and 32 to be positioned, and a clear image of the object under inspection S can be obtained. If sections b4 and c4 are on the same straight line (they are facing each other), as shown in Figure 6(b), that is, if sections b4 and c4 are in a straight line across the front-to-back direction of the optical inspection device 10, backgrounds 31 and 32 cannot be positioned, a clear image of the object under inspection S cannot be obtained, and furthermore, the sensor area corresponding to the back side will be reflected in the sensor area corresponding to the front side.

[0031] Regarding Figure 6, it should be noted that the first mirror group 12 and the second mirror group 21 are arranged either symmetrically with respect to the movement path U, or with slight positional displacement or angular differences. Ideally, as shown in Figure 6(a-1), the sections b4 and c4 should intersect at an angle of less than 180 degrees but as large as possible (e.g., 160-170 degrees). Furthermore, the first mirror group 12 and the second mirror group 21 do not necessarily have to be symmetrical with respect to the movement path U. For example, as shown in Figure 6(a-2), only one of the front and rear optical axes may be tilted downward (or upward) from the horizontal, or as shown in Figure 6(a-3), one may be tilted upward and the other downward. Note that in Figures 6(a-2) and 6(a-3), images of the object S under inspection can be acquired at different timings on the front and back (front and rear), which has the advantage of being able to detect the movement speed of the object S under inspection.

[0032] A line sensor 11, which extends in a long, narrow shape in the front-to-back direction (direction of the dashed line W) of the optical inspection device 10, captures a single elongated image including the front and back surfaces of the object S under inspection at once and outputs it to a computer (not shown). This line sensor 11 is capable of high-speed imaging at short intervals of a few microseconds to several hundred microseconds. By stitching together the elongated images obtained through such high-speed continuous imaging, a computer (not shown) can synthesize an overall image of the object S under inspection moving along the movement path U. Figure 5 shows an example of the synthesized overall image. As shown in Figure 5, the line sensor 11 captures images of numerous granular objects S under inspection, and images of the front and back surfaces are acquired simultaneously.

[0033] Thus, according to this embodiment, the line sensor 11 can stitch together elongated images captured in continuous high-speed motion to create an overall image of multiple objects S being inspected moving along the movement path U.

[0034] The optical inspection apparatus 10 of this embodiment includes a mechanism (first adjustment means and second adjustment means) that allows the tilt angles of the mirrors 15 and 16 to be adjusted, respectively, so that the staring contest shown in Figure 6(b) can be avoided and images can be taken in the state shown in Figures 6(a-1) to 6(a-3).

[0035] Figure 1B is a perspective view showing the first and second adjustment means extracted from Figure 1A and indicated by solid lines. Figure 3 is a schematic perspective view showing the optical axis adjustment of the same embodiment and corresponds to Figure 1B. The adjustment axis X1, which is an adjustment means for adjusting the tilt angle of the support part 17, passes through the center of the mirror 15, which is a planar mirror, and the center of the mirror 16, which is a planar mirror. The adjustment axis X2, which is an adjustment means for adjusting the tilt angle of the support part 37, passes through the center of the mirror 16 in an arbitrary direction. In this embodiment, the adjustment axis X1 and the adjustment axis X2 coincide and are coaxial. The support part 17 that supports the mirrors 15 and 16 is basically supported by a housing (not shown) of the optical inspection device 10 so as not to move. The support part 17 can rotate slightly by about 1 to 5 degrees around the adjustment axis X1 by rotating the first operating part 19 (specifically, an adjustment screw) of the first adjustment means. The first operating part 19 is positioned on one side perpendicular to the adjustment shaft X1 and slightly raises and lowers the edge portion of the support part 17 around the axis. The first operating part 19 (adjustment screw) changes the inclination angle with respect to the housing, i.e., the inclination angle of the mirrors 15 and 16, by rotational operation.

[0036] In the first mirror group 12 of this embodiment, the section b5 between mirror 15 and mirror 16 of the optical axis B2 is parallel to or approximately parallel to the virtual plane V, away from the virtual plane V. Note that "approximately parallel" does not mean strictly parallel where the relative angle is 0 degrees. Specifically, for example, the relative angle may be 0 degrees or more and 1 degree or less, or 0 degrees or more and 5 degrees or less.

[0037] The first mirror group 12 and the second mirror group 21 are arranged by the first adjustment means such that, as shown in Figure 6(a-1), the intervals b4 and c4 are less than 180 degrees but as large as possible (for example, 174 degrees).

[0038] Figure 1C is a perspective view showing the second adjustment mechanism extracted from Figure 1B and indicated by a solid line. The support portion 37 that supports the mirror 16 is basically supported by the aforementioned support portion 17 so as not to move. The second operating portion 39 of the second adjustment mechanism is also supported by the support portion 17. On the other hand, the support portion 37 can be rotated slightly by about 1 to 5 degrees around the adjustment axis X2 by rotating the second operating portion 39 (specifically, the adjustment screw). According to this embodiment, the tilt angle of only the mirror 16 can be adjusted by operating the second operating portion 39. Furthermore, by adjusting the first operating portion 19 and the second operating portion 39 individually, the tilt angles of the mirror 15 and the mirror 16 can be adjusted separately. This makes it possible to fine-tune the first optical path B.

[0039] According to this embodiment, as shown in Figure 1B, the first operating unit 19 of the first adjustment means adjusts the inclination angles of mirrors 15 and 16 in the same direction and by the same amount around the adjustment axis X1 (first adjustment). This first adjustment tilts the section b4 of the optical axis of the first optical path B closest to the object under inspection by the required amount in the vertical direction (double arrow Z direction) of the movement path U, thereby realizing an ideal optical path. However, due to the influence of manufacturing errors and assembly errors of each component, the optical path may not be accurately adjusted with the first adjustment alone. In this case, after the first operation described above, the inclination angle of only mirror 16 is finely adjusted by the second operating unit 39, as shown in Figure 1C (second adjustment). These first and second adjustments make it possible to accurately adjust the first optical path B to an ideal path.

[0040] In this embodiment, adjustment axes X1 and X2 coincide (are coaxial). Therefore, the tilt angle can be adjusted around the common adjustment axis X1 (or adjustment axis X2), making it easy to adjust the mirrors 15 and 16 relative to each other.

[0041] In this embodiment, since the support portion 37 is installed on the support portion 17, the tilt angles of the mirror 15 and the mirror 16 can be adjusted simultaneously by the first adjustment means. Alternatively, in a modified example not shown, the support portion 17 and the support portion 37 may both be separately supported by the housing (not shown) of the optical inspection device 10. In this way, the support portion 17 and the support portion 37 may be arranged separately from each other, and the first adjustment means and the second adjustment means may be independent of each other.

[0042] Furthermore, according to this embodiment, by connecting the optical inspection device 10 with a computer (not shown), and while monitoring the object S under inspection in the state shown in Figure 6(a-2) and Figure 6(a-3), the surface image and back image are compared, the distance and time of movement of a specific object S (for example, a single grain of rice) in both images are detected, and the movement speed and flow rate of the object S are calculated.

[0043] The optical inspection device 10 of this embodiment includes a linear optical line sensor 11 installed so as to intersect with a virtual plane V containing the movement path U of the object to be inspected S; a first mirror group 12 comprising a plurality of mirrors 13, 15, 16 arranged on one side perpendicular to the plane of the virtual plane V, which constitute a first optical path B from the surface of the object to be inspected S moving along the movement path U to the line sensor 11; a second mirror group 21 comprising a plurality of mirrors arranged on the other side perpendicular to the plane of the virtual plane V, which constitute a second optical path C from the back surface of the object to be inspected S moving along the movement path U to the line sensor 11; and two optical lens assemblies 14, 14 arranged in the first optical path B and the second optical path C, respectively. As a result, both sides of the object to be inspected S can be inspected on the virtual plane V containing the line sensor 11 using only one line sensor 11, enabling the optical inspection device 10 to be made thinner and more compact. Furthermore, since only one line sensor 11 is needed, it is cost-effective. As a modified example not shown in the diagram, optical lens assemblies 14, 14 may be placed between the line sensor 11 and the mirror 13, instead of between the mirrors 13, 15 in the first optical path B and the second optical path C. The optical axes B2 and C2 are parallel or nearly parallel between the line sensor 11 and the mirrors 13, 13, and are close to each other. As a further modified example, only one optical lens assembly 14 may be placed between the line sensor 11 and the mirrors 13, 13. By having one optical lens assembly span both the first optical path B and the second optical path C, the number of lens components can be reduced.

[0044] Furthermore, the optical lens assemblies 14, 14 of this embodiment are positioned between adjacent mirrors 13, 15 of the first mirror group 12 arranged on the first optical path B, and between adjacent mirrors 13, 15 of the second mirror group 21 arranged on the second optical path C.

[0045] Next, another embodiment of the present invention will be described. Figure 7 is a plan view (top view) showing another embodiment of the present invention. For the other embodiment, components common to the previously described embodiment are denoted by the same reference numerals and their description is omitted, while different components are described below. The optical inspection apparatus 20 of the other embodiment further comprises an additional optical lens assembly 41. The optical lens assembly 41 is positioned between the front and rear mirrors 13, 13 described above and faces the central region of the line sensor 11. The optical lens assembly 41 is also directed towards the side surface of the object to be inspected S. The side surface is a surface that is parallel to the movement path U and perpendicular to the front and back surfaces. The optical lens assembly 41 constitutes a third optical path D, which is the path of light connecting the line sensor 11 to the object to be inspected S.

[0046] According to another embodiment, the one-end region, the central region, and the other-end region of a single line sensor 11 receive light passing through optical paths B, D, and C, respectively, thereby enabling simultaneous acquisition of images of the front (front), side, and back (rear) surfaces of the object S under inspection.

[0047] Although embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to the illustrated embodiments. Various modifications and variations can be made to the illustrated embodiments within the same scope as the present invention, or within an equivalent scope.

[0048] Figures 8(a) to 8(c) are schematic overall diagrams showing modified optical inspection devices 30, 40, 50, and 60. For example, the line sensor 11 is not limited to one unit; as shown in the modified example in Figure 8(d), different sensors 11b and 11c may be used at the front and rear of the optical inspection device 10 to photograph the front and back surfaces of the object S under inspection, respectively. Furthermore, the line sensors 11b and 11c may be arranged separated by a virtual plane V, or, although not shown, may be arranged asymmetrically with respect to the virtual plane V.

[0049] Furthermore, the mirrors 13, 15, and 16 are not limited to ordinary planar mirrors; they may be half-mirrors, curved mirrors, or prisms, as long as they are capable of bending some or all of the light traveling from the object under inspection S to the line sensor 11. The first mirror group 12 has three mirrors 13, 15, and 16, but the number of mirrors in the first mirror group 12 is limited to two or more, and not to three. The same applies to the second mirror group 21. The first mirror group 12 and the second mirror group 21 are symmetrical with respect to the virtual plane V, but they may be asymmetrical.

[0050] For example, the mirrors of the first mirror group 12 and the second mirror group 21 may each consist of two mirrors 22 and 23, as shown in the modified example in Figure 8(b), or the number of mirrors and optical paths may differ from each other, such as the first mirror group 12 consisting of four mirrors 13, 15, 38, and 16, and the second mirror group 21 consisting of three mirrors 13, 15, and 16, as shown in the modified example in Figure 9.

[0051] Furthermore, as shown in the modified examples in Figures 8(a) to 8(c) and Figure 9, the optical lens assembly 14 may be positioned between the line sensor 11 and the mirror 13. Also, as shown in the modified examples in Figures 8(a) and 8(b), a single optical lens assembly 14 may be positioned across the first optical path B and the second optical path C.

[0052] Furthermore, the support parts 17 and 37 do not need to be table-shaped bases. As a modified example not shown, the support parts 17 and 37 may be linear shafts, one end of which is connected to the mirror and the other end of which is rotatably supported. By rotating such a shaft, the tilt angle of the mirror can be adjusted. The central axis of the shaft is not perpendicular to the reflective surface of the plane mirror. This is because the optical path does not change even if the mirror is rotated around an axis perpendicular to the reflective surface of the plane mirror. Also, the central axis of the shaft may be connected to the center of the mirror, or to a position away from the center of the mirror (the edge of the plane mirror).

[0053] The present invention can also be realized by, for example, extracting some components from one embodiment described above, extracting other components from another embodiment described above, and combining these extracted components. [Industrial applicability]

[0054] The present invention is advantageously utilized in inspection and sorting devices. [Explanation of Symbols]

[0055] 10 Optical inspection device, 11 Line sensor, 12 First mirror group, 13 Mirror, 14 Optical lens assembly, 15, 16 Mirror, 17 Support section, 19 First operating section (adjustment screw), 21 Second mirror group, 27 Support part, 37 Support part, 39 Second operating part (adjustment screw), S: object under inspection, U: movement path, V: virtual plane. X1,X2,X3,X4 Adjustment axis.

Claims

1. One or more optical line sensors are installed along a straight line that intersects a virtual plane containing the movement path of the object under inspection, A group of first mirrors, which includes a plurality of mirrors arranged in one direction perpendicular to the surface of the virtual plane, and which constitute a first optical path from the surface of the object to be inspected moving along the movement path to the optical line sensor, A second group of mirrors, which includes a plurality of mirrors arranged in the other direction perpendicular to the surface of the virtual plane, and which constitute a second optical path from the back surface of the object to be inspected moving along the movement path to the optical line sensor, An optical inspection apparatus comprising two optical lens assemblies, one each positioned in the first and second optical paths, or one optical lens assembly positioned across both the first and second optical paths.

2. The optical inspection apparatus according to claim 1, wherein the two optical lens assemblies are arranged between adjacent mirrors arranged on the first optical path and between adjacent mirrors arranged on the second optical path.

3. The optical inspection apparatus according to claim 1 or 2, further comprising an adjustment means for adjusting at least one of the inclination angle and position of at least one of the mirrors of the first mirror group and the second mirror group.

4. The adjustment means includes a first operating unit for adjusting one of the mirrors on the first optical path, and / or a second operating unit for adjusting another of the mirrors on the first optical path, The optical inspection apparatus according to claim 3, wherein the adjustment means includes a first operating unit for adjusting one of the mirrors on the second optical path and a second operating unit for adjusting another of the mirrors on the second optical path.

5. The adjustment means includes a first operating unit for adjusting the two mirrors on the first optical path, and / or a second operating unit for adjusting either one of the two mirrors, The optical inspection apparatus according to claim 3, wherein the adjustment means includes a first operating unit for adjusting one of the mirrors on the second optical path and a second operating unit for adjusting another of the mirrors on the second optical path.

6. The adjustment means adjusts the tilt angle of the mirror around the adjustment axis, The optical inspection apparatus according to claim 5, wherein the adjustment shafts of the two mirrors adjusted by the first operating unit and the adjustment shaft of either of the mirrors adjusted by the second operating unit are common shafts.

7. A sorting device comprising an optical inspection device as described in claim 1, and a discharge means for removing the object to be inspected from the movement path.

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