JP2023092933A - Inspection device and inspection method - Google Patents

Abstract

To provide an inspection device and an inspection method with which, while suppressing the effect of scattering light, it is possible to inspect an object with a high speed and a high resolution.SOLUTION: An irradiation unit 11 irradiates an object with a plurality of light beams having been collimated along a plurality of optical axes L2 which are two-dimensionally and separately arranged on an XY plane and are parallel to an axis Z, or a plurality of light beams derived by further condensing collimated light beams, the XY plane representing a conveyance plane, the axis X representing a conveyance direction, the axis Y representing a direction perpendicular to the axis X in the XY plane, the axis Z representing a direction perpendicular to the XY plane. A light receiving unit 12, with a one-pixel unit composed of at least one light receiving element being arranged so as to correspond one for one to the plurality of light beams, receives in each pixel the light having passed through an object. The spatial resolution of one-pixel unit composed of at least one light receiving element is greater than or equal to the spatial resolution of the light beams. The arrangement interval of the plurality of optical axes L2 is greater than or equal to a prescribed value in an XY-plane view, and is less than the prescribed value in a YZ-plane view.SELECTED DRAWING: Figure 1

Description

The present invention relates to an inspection apparatus and an inspection method for detecting foreign matter or defects in an object conveyed on a conveying surface in a conveying direction.

2. Description of the Related Art An image reading device for reading an image of an object is sometimes used as an inspection device for detecting foreign substances or defects contained in an object such as food. A transmission inspection apparatus disclosed in Japanese Patent Application Laid-Open No. 2002-200001 employs a configuration in which two light projecting means irradiate an object with light, and an image is captured based on the light transmitted through the object.

JP 2015-219090 A

When a line sensor is used as a light receiving means for receiving transmitted light from an object, the transmitted light is received by a plurality of light receiving elements adjacent along the main scanning direction. Scattered light is generated when the light irradiated to the object is transmitted through the object. It is conceivable to employ a configuration that irradiates light.

In this case, scanning in the main scanning direction can be performed by sequentially irradiating light along each optical axis and sequentially receiving the transmitted light by light receiving elements corresponding to each optical axis. However, when reading an image of an object while scanning in the main scanning direction, scanning takes a long time, so there is a limit to high-speed reading. Such a problem can occur not only in line sensors but also in point sensors or area sensors.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an inspection apparatus and an inspection method capable of inspecting an object at high speed and high resolution while suppressing the influence of scattered light. .

(1) An inspection apparatus according to the present invention is an inspection apparatus for detecting foreign matter or defects in an object conveyed along a conveying direction on a conveying surface, and includes an irradiation section and a light receiving section. When the XY plane is the conveying surface, the X axis is the conveying direction, the Y axis is the direction perpendicular to the X axis in the XY plane, and the Z axis is the direction perpendicular to the XY plane, the irradiation unit A plurality of light beams that are collimated along a plurality of optical axes parallel to the Z-axis that are two-dimensionally spaced in the XY plane, or a plurality of lights obtained by further condensing the collimated light beams. A beam is directed at the object. In the light-receiving section, each pixel unit composed of at least one light-receiving element is arranged in a one-to-one correspondence with the plurality of light beams, and each pixel receives the light transmitted through the object. The spatial resolution of one pixel unit formed by the at least one light receiving element is equal to or greater than the spatial resolution of the light beam. The arrangement intervals of the plurality of optical axes are equal to or greater than a predetermined value when viewed from the XY plane and less than the predetermined value when viewed from the YZ plane.

According to such a configuration, the light emitted along a plurality of optical axes and transmitted through the object can be simultaneously received by the pixels corresponding to the respective optical axes on a one-to-one basis. You can inspect things.

In addition, since the arrangement interval of the plurality of optical axes is equal to or greater than the predetermined value when viewed in the XY plane and less than the predetermined value when viewed in the YZ plane, the incidence of scattered light on adjacent pixels is suppressed, and the Y-axis Orientation resolution can be increased. Therefore, the object can be inspected at high speed and high resolution while suppressing the influence of scattered light.

(2) The irradiation unit may simultaneously irradiate the object with a plurality of collimated light beams or a plurality of light beams obtained by further condensing the collimated light beams.

According to such a configuration, a plurality of light beams can be applied to an object at the same time, and the light transmitted through the object can be simultaneously received by pixels corresponding to each optical axis on a one-to-one basis. can inspect the object.

(3) A plurality of laser light sources may be arranged in the irradiation section.

According to such a configuration, it is possible to irradiate the object with laser light from a plurality of laser light sources along a plurality of optical axes.

(4) The irradiation section may include a laser light source and a branching mechanism for branching the laser light emitted from the laser light source along the plurality of optical axes.

With such a configuration, it is not necessary to provide as many laser light sources as there are pixels, so the manufacturing cost can be reduced.

(5) The branching mechanism may include a diffractive optical element.

According to such a configuration, the laser light emitted from the laser light source can be branched along a plurality of optical axes with a simple configuration using the diffractive optical element, thereby effectively reducing the manufacturing cost. be able to.

(6) A plurality of point sensors may be arranged in the light receiving section.

According to such a configuration, the light that has passed through the object can be simultaneously received by the pixels corresponding to the optical axes on a one-to-one basis using the plurality of point sensors.

(7) A plurality of line sensors may be arranged in the light receiving section.

According to such a configuration, the light transmitted through the object can be simultaneously received by each pixel corresponding to each optical axis on a one-to-one basis by means of a plurality of line sensors.

(8) One area sensor or a plurality of area sensors may be arranged in the light receiving section.

According to such a configuration, the light transmitted through the object can be simultaneously received by each pixel corresponding to each optical axis on a one-to-one basis by one area sensor or a plurality of area sensors.

(9) The light-receiving section may include an optical element that limits the angle of incidence of the light that has passed through the object and guides it to the light-receiving element.

According to such a configuration, it is possible to more effectively suppress scattered light from entering each adjacent pixel.

(10) The optical element may include a telecentric lens.

According to such a configuration, it is possible to effectively limit the incident angle of the light incident on the light receiving element.

(11) The optical element may include a gradient index lens.

According to such a configuration, it is possible to effectively limit the incident angle of the light incident on the light receiving element.

(12) The inspection apparatus may further include an image processing section that generates two-dimensional image data based on a plurality of data obtained by the light receiving section.

According to such a configuration, it is possible to more reliably detect foreign matter or defects contained in the object using two-dimensional image data generated based on a plurality of data obtained by the light receiving section. be.

(13) An inspection method according to the present invention is an inspection method for detecting foreign matter or defects in an object conveyed along a conveying direction on a conveying surface, and includes an irradiation step and a light receiving step. In the irradiation step, when the transport surface is the XY plane, the transport direction is the X axis, the direction perpendicular to the X axis in the XY plane is the Y axis, and the direction perpendicular to the XY plane is the Z axis, A plurality of light beams that are collimated along a plurality of optical axes parallel to the Z-axis that are two-dimensionally spaced in the XY plane, or a plurality of lights obtained by further condensing the collimated light beams. A beam is directed at the object. In the light-receiving step, a pixel unit composed of at least one light-receiving element receives light transmitted through the object by a light-receiving unit arranged in a one-to-one correspondence with the plurality of light beams. receive light. The spatial resolution of one pixel unit formed by the at least one light receiving element is equal to or greater than the spatial resolution of the light beam. The arrangement intervals of the plurality of optical axes are equal to or greater than a predetermined value when viewed from the XY plane and less than the predetermined value when viewed from the YZ plane.

According to the present invention, an object can be inspected at high speed and high resolution while suppressing the influence of scattered light.

It is a schematic diagram showing an example of composition of an inspection device concerning one embodiment of the present invention. FIG. 4 is a schematic diagram for explaining a light receiving position in each line sensor; FIG. 4 is a schematic diagram for explaining image processing based on data obtained by receiving laser light at each light receiving position; It is a block diagram showing an example of an electrical configuration of an inspection device. It is a figure for demonstrating the distance between each optical axis, and shows XY plane view. It is a figure for demonstrating the distance between each optical axis, and has shown YZ plane view.

1. Configuration Example of Inspection Apparatus FIG. 1 is a schematic diagram showing a configuration example of an inspection apparatus 1 according to an embodiment of the present invention. This inspection apparatus 1 is an apparatus for detecting foreign matter or defects contained in an object W such as food.

In this inspection apparatus 1, the object W conveyed in the conveying direction D1 (X-axis direction) is irradiated with light from the irradiation unit 11, and the transmitted light is read by the light receiving unit 12, thereby detecting foreign matter contained in the object W. Or defects can be detected. The inspection apparatus 1 is provided with a transport mechanism 2 for transporting the object W along the transport direction D1.

The inspection device 1 includes an irradiation section 11 and a light receiving section 12 . The irradiation unit 11 and the light receiving unit 12 are arranged so as to face each other with the transport mechanism 2 interposed therebetween. As a result, light emitted from the irradiation unit 11 to the object W and transmitted through the object W is received by the light receiving unit 12 .

The irradiation unit 11 irradiates the object W with laser light along a plurality of optical axes L. As shown in FIG. Specifically, a plurality of collimated light beams or a plurality of light beams obtained by further condensing the collimated light beams are irradiated along a plurality of optical axes L to the object W at the same time. In this embodiment, the irradiation unit 11 includes a laser diode 111, a diffractive optical element 112, a collimator lens 113, and the like. The diffractive optical element 112 is arranged between the laser diode 111 and the transport mechanism 2 , and the collimator lens 113 is arranged between the diffractive optical element 112 and the transport mechanism 2 .

The laser diode 111 is an example of a laser light source that emits laser light. The wavelength of the laser light emitted from the laser diode 111 is in the infrared region (for example, 780 nm to 1 mm). More specifically, the laser diode 111 emits laser light in at least one of a near-infrared region (eg, 780 nm to 2 μm) and a mid-infrared region (eg, 2 to 4 μm). A laser beam in such a wavelength range can easily pass through the object W. As shown in FIG.

In this embodiment, one laser diode 111 is provided, and laser light is emitted from the laser diode 111 toward the transport mechanism 2 . The direction of emission of laser light from the laser diode 111 is orthogonal to the conveying direction D1 of the object W and parallel to the facing direction of the irradiation unit 11 and the light receiving unit 12 .

Also, the number of laser diodes 111 is not limited to one, and two or more may be provided. Also, the laser light source may be composed of a light source other than the laser diode 111 . Specifically, solid-state lasers such as YAG (yttrium aluminum garnet), gas lasers such as HeNe (helium neon), and Vertical Cavity Surface Emitting Laser (VCSEL), which is a type of semiconductor laser. may be used as the laser light source, and a collimating lens, fiber, or the like may be included in the laser light source.

The diffractive optical element 112 constitutes a branching mechanism that branches the laser light emitted from the laser diode 111 along a plurality of optical axes L (optical axis L1). That is, the number of optical axes L 1 of laser light emitted from the diffractive optical element 112 is greater than the number of optical axes L 0 of laser light incident on the diffractive optical element 112 . The diffractive optical element 112 splits the laser light incident from the laser diode 111 so that the light intensity of the laser light along each optical axis L1 becomes uniform.

The diffractive optical element 112 is a so-called DOE (Diffractive Optical Element), and is formed in a plate shape with an incident surface 112A and an output surface 112B extending in parallel. The incident surface 112A extends in a direction orthogonal to the optical axis L0 of the laser light emitted from the laser diode 111. As shown in FIG. A fine structure is formed on the emission surface 112B, and the laser light is diffracted by the fine structure and branched into a plurality of optical axes L1. At least part of the plurality of optical axes L1 may be inclined with respect to the optical axis L0 of the laser light incident on the diffractive optical element 112, but the invention is not limited to this.

The collimating lens 113 converts the laser beams emitted from the diffractive optical element 112 along the plurality of optical axes L1 into a plurality of parallel optical axes L2. Each optical axis L2 of the laser light emitted from the collimator lens 113 is orthogonal to the conveying direction D1 of the object W and parallel to the direction in which the irradiation unit 11 and the light receiving unit 12 face each other. However, each optical axis L2 of the laser light emitted from the collimator lens 113 is not limited to the direction perpendicular to the transport direction D1 of the object W. FIG. Also, the laser light emitted from the collimating lens 113 may be condensed along each optical axis L2 by a condensing lens.

A target object W transported by the transport mechanism 2 is irradiated with laser light emitted from the collimator lens 113 along a plurality of optical axes L2. That is, the object W is irradiated with laser light at a plurality of positions, and the laser light that enters the object W from each position passes through the object W. As shown in FIG. The laser light incident on the object W along a plurality of optical axes L (optical axis L2) may be reflected or absorbed by foreign matter or defects contained in the object W when passing through the object W. be.

The light receiving unit 12 receives laser light that has passed through the object W. As shown in FIG. The light receiving unit 12 is provided with a plurality of line sensors on a plane. In this embodiment, three line sensors (the first line sensor 121, the second line sensor 122, and the third line sensor 123) are provided. It is good if there is Moreover, it is possible to use various sensors such as a point sensor or an area sensor without being limited to the line sensor. For example, the light receiving unit 12 may have a plurality of point sensors arranged on a plane, or may have one area sensor or a plurality of area sensors arranged on a plane. A point sensor is associated with each optical axis L2 of the laser beam and individually receives the laser beam that has passed through the object W along each optical axis L2. The area sensor is associated with a plurality of optical axes L2 of laser light and simultaneously receives laser light transmitted through the object W along the plurality of optical axes L2. However, the plurality of line sensors, the plurality of point sensors, or the plurality of area sensors are not limited to being arranged on a plane.

The first line sensor 121 , the second line sensor 122 and the third line sensor 123 are integrally held by a holding member 124 . Accordingly, the line sensors 121, 122, and 123 are fixed so that their relative positional relationships do not deviate. Each line sensor 121 , 122 , 123 has a plurality of light receiving elements 125 . Each light receiving element 125 is composed of, for example, a photodiode. Each light receiving element 125 has a wavelength in the infrared region (eg, 780 nm to 1 mm), more specifically, a laser in at least one of the near-infrared region (eg, 780 nm to 2 μm) and the mid-infrared region (eg, 2 to 4 μm). Light intensity can be detected. Such a light receiving element 125 may be an InGaAs sensor or a Si photodiode. Each of the line sensors 121, 122, 123 has an elongated shape. 123 extends. The light receiving section 12 may be provided with an optical element that limits the incident angle of the laser light that has passed through the object W and guides it to the light receiving element 125 . In this case, a telecentric lens, a gradient index lens, or the like can be exemplified as the optical element. According to this configuration, by limiting the incident angle, it is possible to more effectively suppress the scattered light from entering each adjacent pixel, and it is possible to shorten the distance between the optical axes.

The first line sensor 121, the second line sensor 122, and the third line sensor 123 held by the holding member 124 extend along a direction intersecting the conveying direction D1 of the object W, respectively. In this embodiment, the line sensors 121, 122, and 123 are arranged side by side in the transport direction D1 so as to extend in a direction perpendicular to the transport direction D1 of the object W. As shown in FIG. Specifically, the line sensors 121, 122, and 123 are arranged at equal intervals in the transport direction D1 and extend parallel to each other.

By arranging the line sensors 121, 122, 123 as described above, the plurality of light receiving elements 125 provided in the line sensors 121, 122, 123 are arranged in a matrix. That is, in the light receiving section 12, a plurality of light receiving elements 125 are arranged in a plurality of rows along the arrangement direction D2 and a plurality of columns along the transport direction D1. In the light receiving section 12, the light transmitted through the object W is received by a plurality of light receiving elements 125 arranged in a matrix.

The transport mechanism 2 is configured to include, for example, a conveyor. In this embodiment, an endless belt 22 is wound around two rotating shafts 21 extending parallel to each other, thereby forming a conveying mechanism 2 made up of a belt conveyor. The object W is placed on the surface of the belt 22 that constitutes the conveying surface. By rotating the rotary shaft 21 in this state, the belt 22 can be rotated and the object W can be transported in the transport direction D1. The transport plane constitutes the XY plane, and the direction perpendicular to the XY plane is the Z axis.

In order for the line sensors 121, 122, and 123 to receive the light that has passed through the object W, the belt 22 is made of a light-transmitting material. That is, the laser light that has passed through the object W passes through the belt 22 and is received by each of the line sensors 121 , 122 and 123 .

However, the transport mechanism 2 is not limited to the above configuration as long as it is configured so as not to block the light transmitted through the object W. FIG. For example, it is possible to have a configuration in which belts are respectively hung on both ends of the two rotating shafts 21, and a light-transmitting tray on which the object W is placed is provided so as to straddle these belts, and the object W is conveyed. good. Further, in the case of drop conveyance using gravity, the conveying surface does not have an entity such as a belt, and the conveying direction is the direction of gravity.

2. Light-receiving position of each line sensor FIG. Each line sensor 121, 122, 123 provided in the light receiving section 12 has the same shape, and each has a plurality of pixels 126 along the arrangement direction D2. Each pixel 126 corresponds to the light receiving surface of each light receiving element 125 .

In this embodiment, the line sensors 121, 122, and 123 are arranged at positions shifted from each other in the arrangement direction D2. The amount of shift in the array direction D2 between the line sensors 121, 122, and 123 is an integral multiple of the width of the pixels 126 along the array direction D2. For example, in the example of FIG. 2, the shift amount S1 in the arrangement direction D2 of the second line sensor 122 with respect to the first line sensor 121 is 1 pixel. Also, the shift amount S2 in the arrangement direction D2 of the third line sensor 123 with respect to the second line sensor 122 is two pixels. However, the amount of shift in the arrangement direction D2 between the line sensors 121, 122, and 123 is not limited to one pixel or two pixels, and may be three pixels or more.

As a result, the pixels 126 of the line sensors 121, 122, and 123 adjacent in the transport direction D1 overlap each other in the transport direction D1. That is, the plurality of pixels 126 provided in each line sensor 121, 122, 123 are not only arranged in the arrangement direction D2 in each line sensor 121, 122, 123, but also adjacent line sensors 121, 122, 123 They are also arranged in the transport direction D1.

In this embodiment, not all of the plurality of pixels 126 provided in each of the line sensors 121, 122, and 123 receive the laser light, but only some of the pixels 126 receive the laser light. . Specifically, as shown by hatching in FIG. 2, in each of the line sensors 121, 122, and 123, pixels 126 positioned at regular intervals in the arrangement direction D2 are defined as light receiving positions 126A, 126B, and 126C, and light receiving positions 126A, 126B, and 126C are arranged. Laser light is received at 126B and 126C. However, in each of the line sensors 121, 122 and 123, a configuration in which the light receiving elements 125 are provided only at positions corresponding to the respective light receiving positions 126A, 126B and 126C may be adopted.

Each light receiving position 126A, 126B, 126C corresponds to a plurality of optical axes L2 of laser light emitted from the collimating lens 113. As shown in FIG. That is, each light receiving position 126A, 126B, 126C is arranged on the extension line of each optical axis L2. Therefore, the number of optical axes L2 and the number of light receiving positions 126A, 126B, 126C are the same. Each of the light receiving positions 126A, 126B, and 126C corresponds to each optical axis L2 on a one-to-one basis, and is provided so that the positions in the arrangement direction D2 do not overlap each other when viewed along the transport direction D1. .

Thus, one means of avoiding crosstalk is to establish a one-to-one correspondence between a plurality of light beams and light-receiving elements on a pixel-by-pixel basis. One pixel consists of at least one light receiving element. In the present embodiment, each light receiving element 125 constitutes one pixel, but one pixel is not limited to one light receiving element, and one pixel may be composed of a plurality of light receiving elements.

The spatial resolution of one pixel unit formed by at least one light receiving element is greater than or equal to the spatial resolution of the light beam on the inspection surface of the object W. FIG. Here, the spatial resolution of the light beam corresponds to the beam diameter of the light beam on the inspection surface of the object W. FIG. In other words, it has the ability to identify two adjacent points within the beam diameter of the light beam in one pixel unit composed of at least one light-receiving element.

It is preferable that the distance between the light receiving positions 126A, 126B, and 126C is a distance that suppresses the scattered light generated when the laser light is transmitted through the object W from entering each other. Therefore, it is also possible to change the distance between each light receiving position 126A, 126B, 126C according to the type of the object W. FIG. For example, if the diffractive optical element 112 is switched according to the type of the object W to change the distance between the optical axes L2 branched by the diffractive optical element 112, the laser light along each optical axis L2 can be changed. The distance between each incident light receiving position 126A, 126B, 126C can be changed. Alternatively, it is also possible to change the distance between the light receiving positions 126A, 126B, and 126C by switching the collimator lens 113 to one having a different focal length.

The distance A between the line sensors 121, 122, and 123 adjacent to each other is preferably a distance that suppresses the scattered light generated when the laser light is transmitted through the object W from entering each other, as described above. Therefore, it is possible to change the distance A between the line sensors 121, 122, 123 according to the type of the object W. FIG. For example, each of the line sensors 121, 122, and 123 may be configured to be slidable in the transport direction D1, and each of the line sensors 121, 122, and 123 may be slid according to the type of object W.

However, the line sensors 121, 122, and 123 are not limited to extending in the direction orthogonal to the transport direction D1, and may extend in a direction intersecting the transport direction D1. In this case, the positions of the light receiving positions 126A, 126B, and 126C in the direction intersecting the conveying direction D1 should not overlap each other.

3. Image Processing FIG. 3 is a schematic diagram for explaining image processing based on data obtained by receiving laser beams at the respective light receiving positions 126A, 126B, and 126C. Laser light transmitted through the object W conveyed along the conveying direction D1 is incident on the light receiving positions 126A, 126B, and 126C. The positions are provided so as not to overlap each other.

Assuming that these light receiving positions 126A, 126B and 126C are arranged on the same straight line along the arrangement direction D2, as shown in FIG. Transmitted light from the object W, which is positioned without gaps and is transported along the transport direction D1, is received without omission at any one of the light receiving positions 126A, 126B, and 126C.

However, since the positions of the line sensors 121, 122, and 123 in the transport direction D1 are different, the light receiving positions 126A, 126B, and 126C start receiving light from the object W at different timings. The time difference between the light receiving start timings can be calculated based on the distance A in the transport direction D1 between the line sensors 121, 122, and 123 and the transport speed of the object W transported along the transport direction D1. .

A plurality of data obtained by receiving laser beams with each of the line sensors 121, 122, and 123 while conveying the object W is a plurality of data along the conveying direction D1 extending parallel to each other at intervals in the arrangement direction D2. contains linear data of That is, the data obtained by receiving the laser light with the first line sensor 121 includes a plurality of linear data extending parallel to each other at intervals corresponding to the distances between the respective light receiving positions 126A. Similarly, the data obtained by receiving the laser light with the second line sensor 122 includes a plurality of linear data extending parallel to each other at intervals corresponding to the distances between the respective light receiving positions 126B. The data obtained by receiving the laser light with the third line sensor 123 includes a plurality of linear data extending parallel to each other at intervals corresponding to the distances between the respective light receiving positions 126C.

In this embodiment, image processing for generating two-dimensional image data is performed based on a plurality of data obtained by each of these line sensors 121 , 122 and 123 . Specifically, a plurality of data obtained by each of the line sensors 121, 122, and 123 are synthesized based on the above-described time difference in light receiving start timing, thereby obtaining two-dimensional image data from which the influence of the time difference has been removed. generated. That is, image processing is performed according to the positions of the light receiving positions 126A, 126B, and 126C in the arrangement direction D2. The two-dimensional image data generated in this way is similar to the image data obtained when the light receiving positions 126A, 126B, and 126C are arranged on the same straight line along the arrangement direction D2 as shown in FIG. image data.

4. Electrical Configuration FIG. 4 is a block diagram showing an example of the electrical configuration of the inspection apparatus 1. As shown in FIG. The operation of the inspection apparatus 1 according to this embodiment is controlled by the controller 3 . The control unit 3 is configured by a processor including, for example, a CPU (Central Processing Unit). The control unit 3 functions as a light emission control unit 31, a light reception processing unit 32, an image processing unit 33, a foreign matter/defect detection unit 34, and the like by the CPU executing programs.

The light emission control unit 31 switches the light emission from the laser diode 111 to an on state or an off state by controlling power supply to the laser diode 111 . In this embodiment, the laser diode 111 is controlled to be in the ON state while the transport mechanism 2 is being driven. However, if a sensor (not shown) for detecting the presence or absence of the object W transported by the transport mechanism 2 is provided, the laser diode 111 is turned on only when the object W passes over the plurality of optical axes L2. state. Alternatively, the configuration may be such that the laser diode 111 can be manually switched between the ON state and the OFF state.

The light reception processing unit 32 processes signals input from each line sensor (the first line sensor 121, the second line sensor 122, and the third line sensor 123) of the light receiving unit 12. FIG. Each of the line sensors 121, 122, and 123 outputs an analog signal having an intensity corresponding to the amount of light received by the plurality of light receiving elements 125, and the analog signal is converted into a digital signal by an A/D converter (not shown). After that, it is input to the control unit 3 .

The image processing unit 33 performs image processing for generating image data based on the input signals from the line sensors 121 , 122 and 123 processed by the light reception processing unit 32 . In this image processing, as described with reference to FIG. 3, two-dimensional image data is generated based on a plurality of data obtained by receiving laser light at each of the light receiving positions 126A, 126B, and 126C.

The foreign matter/defect detection unit 34 detects foreign matter or defects included in the object W based on the two-dimensional image data generated by the image processing unit 33 . For example, if a partial low-brightness region in the image data caused by the reflection or absorption of the laser beam by a foreign substance or defect included in the object W is specified, the region is regarded as a region corresponding to the foreign substance or defect. can be detected. Thus, the foreign matter/defect detection unit 34 can detect the presence or absence of foreign matter or defects in the object W by analyzing the image data. The foreign matter/defect detection unit 34 can also detect the position or size of a foreign matter or defect in the object W. FIG.

However, the control unit 3 may be configured so as not to function as the foreign matter/defect detection unit 34 . In this case, the inspection apparatus 1 that simply reads the image of the object W is configured. Based on the image data generated by such an inspection apparatus 1, the user can also visually confirm foreign matter or defects.

Further, even if the two-dimensional image data in which the influence of the time difference between the light receiving start timings of the line sensors 121, 122, and 123 is removed as described with reference to FIG. Or it is possible to detect defects. That is, a plurality of data obtained by each of the line sensors 121, 122, and 123 may be combined without considering the time difference between light receiving start timings, and foreign matter or defects may be detected without combining these data. is also possible.

The branching mechanism is not limited to the one configured by the diffractive optical element 112, and may have another configuration as long as it can split the laser light along a plurality of optical axes L2. Also, for example, a configuration in which a plurality of fiber lasers are arranged can be adopted. That is, the configuration is not limited to the configuration in which the laser light is branched along a plurality of optical axes L2, and a configuration in which a plurality of laser light sources are arranged on a plane may be used. The plane constitutes an emission surface for a plurality of laser beams. However, the multiple laser light sources are not limited to being arranged on a plane.

5. Distance Between Optical Axes FIGS. 5 and 6 are diagrams for explaining the distances between the optical axes L2. FIG. 5 shows the view from the XY plane, and FIG. 6 shows the view from the YZ plane. As shown in FIG. 5, the plurality of optical axes L2 are two-dimensionally spaced apart on the XY plane. That is, the plurality of optical axes L2 may be arranged in at least two directions as shown in FIG. 5 instead of being arranged in only one direction on the XY plane. Also, instead of the configuration in which the plurality of optical axes L2 are aligned as shown in FIG. 5, the configuration may be such that they are arranged irregularly. In this case, the plurality of optical axes L2 may be randomly arranged, and at least some of the optical axes L2 may overlap each other when viewed in the YZ plane. The plurality of optical axes L2 are parallel to the Z-axis, which is a direction perpendicular to the XY plane, but the concept of "parallel" here includes "substantially parallel" slightly inclined with respect to the Z-axis. .

As shown in FIG. 5, the arrangement interval of the plurality of optical axes L2 is a predetermined value V or more in the XY plane view. That is, not only is the arrangement interval between the optical axes L2 adjacent in the Y direction equal to or greater than the predetermined value V, but also the arrangement interval between the optical axes L2 adjacent in a direction different from the Y direction is equal to or greater than the predetermined value V. This means that the arrangement interval between all the optical axes L2 adjacent to each other in the XY plane view is the predetermined value V or more. This makes it possible to reduce the influence of scattered light from the adjacent optical axis L2.

On the other hand, in the YZ plane view, the arrangement interval of the plurality of optical axes L2 is less than the predetermined value V, as shown in FIG. That is, the arrangement interval between all the optical axes L2 adjacent to each other in the YZ plane view is less than the predetermined value V, and as described above, some of the optical axes L2 may overlap each other in the YZ plane view.

6. Effect (1) In the present embodiment, the laser light that has been irradiated along a plurality of optical axes L (optical axis L2) and has passed through the object W is applied to each pixel ( Since light can be received simultaneously at a plurality of light receiving positions 126A, 126B, 126C), the object W can be inspected at high speed and high resolution.

Further, as shown in FIGS. 5 and 6, since the arrangement interval of the plurality of optical axes L2 is equal to or greater than the predetermined value V in the XY plane view and less than the predetermined value V in the YZ plane view, Even when a plurality of light receiving positions 126A, 126B, and 126C simultaneously receive the laser beams thus obtained, it is possible to suppress the incidence of scattered light on the adjacent light receiving positions 126A, 126B, and 126C, and to improve the resolution. can keep. Therefore, the object W can be inspected at high speed and high resolution while suppressing the influence of scattered light.

(2) In addition, in the present embodiment, by branching the laser light with the diffraction optical element 112 as a branching mechanism, there is no need to provide laser light sources for the number of light receiving positions 126A, 126B, and 126C, thereby reducing manufacturing costs. can do. In particular, in this embodiment, the laser beam can be split with a simple configuration using the diffractive optical element 112, so the manufacturing cost can be effectively reduced.

(3) In addition, in the present embodiment, using two-dimensional image data generated based on a plurality of data obtained by the light receiving unit 12, foreign matter or defects contained in the object W are detected more reliably. Is possible. In particular, in the present embodiment, a two-dimensional image corresponding to the image of the object W is obtained by performing image processing according to the positions in the array direction D2 of the plurality of light receiving positions 126A, 126B, and 126C as described with reference to FIG. Since the data can be generated, it is possible to detect foreign matter or defects contained in the object W more reliably.

1 inspection device 2 transport mechanism 3 control unit 11 irradiation unit 12 light receiving unit 31 light emission control unit 32 light reception processing unit 32 light reception processing unit 33 image processing unit 34 foreign matter/defect detection unit 111 laser diode 112 diffractive optical element 121, 122, 123 line Sensors 126A, 126B, 126C Light receiving position D1 Conveyance direction D2 Arrangement direction

Claims (13)

An inspection device for detecting foreign matter or defects in an object conveyed along a conveying direction on a conveying surface,
Two-dimensional on the XY plane, where the transport plane is the XY plane, the transport direction is the X axis, the direction perpendicular to the X axis in the XY plane is the Y axis, and the direction perpendicular to the XY plane is the Z axis. a plurality of collimated light beams, or a plurality of further focused light beams of the collimated light beams, along a plurality of optical axes parallel to the Z-axis that are spatially spaced apart from each other; an irradiation unit that irradiates to
a light-receiving unit in which one pixel unit composed of at least one light-receiving element is arranged so as to correspond one-to-one with the plurality of light beams, and the light transmitted through the object is received by each pixel;
the spatial resolution of one pixel unit formed by the at least one light receiving element is equal to or greater than the spatial resolution of the light beam;
The inspection apparatus, wherein the arrangement interval of the plurality of optical axes is equal to or greater than a predetermined value when viewed from the XY plane and is less than the predetermined value when viewed from the YZ plane. 2. The inspection apparatus according to claim 1, wherein the irradiation unit simultaneously irradiates the object with a plurality of collimated light beams or a plurality of light beams obtained by further condensing the collimated light beams. 2. The inspection apparatus according to claim 1, wherein a plurality of laser light sources are arranged in said irradiation unit. 2. The inspection apparatus according to claim 1, wherein said irradiation unit includes a laser light source and a branching mechanism for branching laser light emitted from said laser light source along said plurality of optical axes. 5. The inspection apparatus according to claim 4, wherein said branching mechanism includes a diffractive optical element. The inspection apparatus according to any one of claims 1 to 5, wherein a plurality of point sensors are arranged in said light receiving section. The inspection apparatus according to any one of claims 1 to 5, wherein a plurality of line sensors are arranged in said light receiving section. The inspection apparatus according to any one of claims 1 to 5, wherein one area sensor or a plurality of area sensors are arranged in the light receiving section. The inspection apparatus according to any one of claims 1 to 8, wherein the light-receiving unit includes an optical element that limits an incident angle of the light transmitted through the object and guides the light to the light-receiving element. 10. The inspection device according to claim 9, wherein said optical element includes a telecentric lens. 10. The inspection apparatus according to claim 9, wherein said optical element includes a gradient index lens. The inspection apparatus according to any one of claims 1 to 11, further comprising an image processing section that generates two-dimensional image data based on a plurality of data obtained by said light receiving section. An inspection method for detecting foreign matter or defects in an object conveyed along a conveying direction on a conveying surface,
Two-dimensional on the XY plane, where the transport plane is the XY plane, the transport direction is the X axis, the direction perpendicular to the X axis in the XY plane is the Y axis, and the direction perpendicular to the XY plane is the Z axis. a plurality of collimated light beams, or a plurality of further focused light beams of the collimated light beams, along a plurality of optical axes parallel to the Z-axis that are spatially spaced apart from each other; an irradiation step of irradiating to
a light-receiving step of receiving light transmitted through the object by a light-receiving section in which one pixel unit composed of at least one light-receiving element is arranged so as to correspond one-to-one with the plurality of light beams; including
the spatial resolution of one pixel unit formed by the at least one light receiving element is equal to or greater than the spatial resolution of the light beam;
The inspection method, wherein the arrangement interval of the plurality of optical axes is equal to or greater than a predetermined value when viewed from the XY plane and is less than the predetermined value when viewed from the YZ plane.

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