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WO2023120424A1 - 照明装置 - Google Patents

照明装置 Download PDF

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Publication number
WO2023120424A1
WO2023120424A1 PCT/JP2022/046422 JP2022046422W WO2023120424A1 WO 2023120424 A1 WO2023120424 A1 WO 2023120424A1 JP 2022046422 W JP2022046422 W JP 2022046422W WO 2023120424 A1 WO2023120424 A1 WO 2023120424A1
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WO
WIPO (PCT)
Prior art keywords
light
light guide
guide plate
control surface
illumination
Prior art date
Application number
PCT/JP2022/046422
Other languages
English (en)
French (fr)
Japanese (ja)
Inventor
真一 阿南
忠史 村上
Original Assignee
パナソニックＩｐマネジメント株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by パナソニックＩｐマネジメント株式会社 filed Critical パナソニックＩｐマネジメント株式会社
Publication of WO2023120424A1 publication Critical patent/WO2023120424A1/ja

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21S—NON-PORTABLE LIGHTING DEVICES; SYSTEMS THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLE EXTERIORS
    • F21S2/00—Systems of lighting devices, not provided for in main groups F21S4/00 - F21S10/00 or F21S19/00, e.g. of modular construction
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21Y—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
    • F21Y2115/00—Light-generating elements of semiconductor light sources
    • F21Y2115/10—Light-emitting diodes [LED]

Definitions

  • the present disclosure relates to lighting devices.
  • Patent Document 1 an irradiation device that irradiates light for visual inspection of products.
  • Patent Document 1 a plurality of recesses are formed on one plate surface of the light guide plate, and the surface of each recess is formed with a smooth concave curved surface.
  • the light incident on the light guide plate is reflected by the concave portion so as to spread and is emitted to the outside from the other plate surface of the light guide plate, and is irradiated to a predetermined target. It is configured so that it can be observed through the light guide plate from the plate surface side.
  • an LED light source
  • the object is arranged on one side of the light guide plate, and the object is observed on the other side of the light guide plate.
  • Cameras etc. are arranged for this purpose.
  • a prism or the like is formed on the other side of the light guide plate, and the light emitted from the LED is reflected by the prisms formed on the light guide plate to the one side of the light guide plate, and the object is irradiated. .
  • part of the light emitted from the LED may be reflected by the prism to the other surface side of the light guide plate and directly enter the camera. If the amount of light directly incident on the camera is large, the contrast of the camera image will be lowered, and the accuracy of the appearance inspection will be lowered.
  • the object is irradiated with the diffused light reflected by the concave portion, so that only part of the light emitted from the light guide plate can be irradiated onto the object, resulting in a low illumination rate.
  • An object of the present disclosure is to provide an illumination device capable of illuminating an object with light at a high illumination rate while suppressing the amount of light that directly enters the camera from the light source.
  • a lighting device includes a light source, a first surface that emits light incident from the light source, and a first surface that faces the first surface to reflect and/or reflect the light.
  • a light guide plate having a second surface on which a plurality of refracting prisms are arranged, and a transmitting portion that houses the light source and the light guide plate and transmits the light to the outside of the first surface and the second surface.
  • the light source emits the light from at least two directions to the light guide plate, and each of the prisms has a first surface in which the first surface and the second surface face each other.
  • a lighting device comprising a control surface and a bottom surface connecting said second control surface, wherein said first control surface and said second control surface are coated with an antireflection coating.
  • the present disclosure it is possible to irradiate the object with light at a high illumination rate while suppressing the amount of light that directly enters the camera from the light source.
  • FIG. 1 is a schematic configuration diagram of an appearance inspection apparatus according to Embodiment 1;
  • FIG. FIG. 2 is a schematic cross-sectional view of a main part of the lighting device;
  • FIG. 2B is a partially enlarged view of FIG. 2A;
  • FIG. 4 is a schematic cross-sectional view of a main part of the lighting device when an object is irradiated with illumination light in a first lighting mode;
  • FIG. 10 is a schematic cross-sectional view of a main part of the lighting device when the object is irradiated with the illumination light in the second lighting mode;
  • FIG. 11 is a schematic cross-sectional view of a main part of the lighting device when the object is irradiated with the illumination light in the third lighting mode;
  • FIG. 4 is a schematic diagram of an image of an object when the object is irradiated with illumination light in a first illumination mode;
  • FIG. 5 is a schematic diagram of an image of an object when the object is irradiated with illumination light in the second illumination mode;
  • FIG. 10 is a schematic diagram of an image of an object when the object is irradiated with illumination light in a third illumination mode;
  • FIG. 4 is a diagram showing a signal processing process of an image signal;
  • FIG. 4 is a diagram showing a signal processing process of an image signal;
  • FIG. 4 is an enlarged cross-sectional view of an optical path changing portion in the first light guide plate according to the embodiment;
  • FIG. 5 is an enlarged cross-sectional view of an optical path changing portion in a first light guide plate according to another embodiment of the present embodiment;
  • FIG. 1 shows a schematic configuration diagram of a visual inspection apparatus according to this embodiment.
  • the direction parallel to the direction passing through the center of the first surface light source 10 assembled in the illumination device 100 and perpendicular to the first surface 11a of the first light guide plate 11 is referred to as the Z direction.
  • the direction parallel to the first surface 11a of the first light guide plate 11 is called the X direction, and is parallel to the first surface 11a of the first light guide plate 11 and orthogonal to the X direction.
  • the direction is sometimes called the Y direction.
  • the side on which the camera 200 is arranged may be referred to as the upper side, the upper side, or the upper side.
  • the side on which the object 600 is arranged may be referred to as the bottom, the lower side, or the lower side.
  • a plane parallel to each of the X direction and the Y direction is sometimes called an XY plane.
  • the case where the lighting device 100 is viewed from the Z direction is sometimes called "planar view”. Also, a case where the illumination device 100 or its cross section is viewed from the X direction or the Y direction is sometimes referred to as a "cross section”.
  • perpendicular and parallel mean that objects to be compared included in the visual inspection apparatus 500 are orthogonal to each other, including the manufacturing tolerances and assembly tolerances of the components that make up the visual inspection apparatus 500. It means that they are parallel to each other. It does not mean that the objects of comparison are strictly orthogonal or parallel to each other.
  • the appearance inspection device 500 includes an illumination device 100, a camera (imaging device) 200, and an image analysis device 300. Moreover, the visual inspection apparatus 500 further includes an illumination power source 400 and an illumination control device 410 .
  • the illumination device 100 has first to third surface light sources 10, 20, and 30.
  • the first to third surface light sources 10, 20, 30 are superimposed in this order from above.
  • the first to third surface light sources 10, 20, 30 irradiate illumination light toward the object 600, respectively. However, in each of the first to third surface light sources 10, 20, and 30, the irradiation area of the illumination light directed toward the object 600 (see FIG. 2B, hereinafter referred to as the first to third irradiation areas 13, 23, and 33) ) are arranged so that only a part of them overlap in plan view.
  • the structures of the illumination device 100 and the first to third surface light sources 10, 20, 30 will be detailed later.
  • the lighting power supply 400 controls the light source included in each of the first to third surface light sources 10, 20, 30, in this case, LED (light source) 60 (Light Emitting Diode; FIG. 2A-2C).
  • LED (light source) 60 Light Emitting Diode; FIG. 2A-2C.
  • the LED 60 supplied with a predetermined power emits light to generate illumination light.
  • the lighting control device 410 controls the timing and period of generating illumination light for each of the first to third surface light sources 10, 20, and 30 according to a program or sequence prepared in advance, that is, when the illumination light is turned on. A control signal for controlling the timing (to light up) and the ON period is output to the lighting power source 400 . In addition, according to a program or sequence prepared in advance, the lighting control device 410 controls the timing and period of stopping the illumination light for each of the first to third surface light sources 10, 20, and 30. A control signal for controlling the timing of turning off (turning off the light) and the off period is output to the lighting power source 400 .
  • the lighting control device 410 has a CPU (Central Processing Unit) (not shown), and the functions described above are realized by executing the programs or sequences described above on the CPU.
  • CPU Central Processing Unit
  • the camera 200 captures an image of the object 600 irradiated with the illumination light from the illumination device 100 and acquires the image.
  • the camera 200 has a lens and an imaging device (both not shown).
  • a well-known CCD (Charge Coupled Device) image sensor or CMOS (Complementary Metal Oxide Semiconductor) image sensor is used as an imaging device.
  • the image analysis device 300 includes at least an image processing section 310 , a storage section 320 and a display section 330 .
  • the image processing unit 310 has a CPU, a GPU (Graphics Processing Unit), or both (neither is shown).
  • the image processing unit 310 receives an image captured by the camera 200 as an electrical signal (hereinafter also referred to as an image signal), and performs various signal processing such as noise removal processing and edge enhancement processing on the image signal. is configured to allow These signal processing functions are realized by executing a predetermined sequence or the like by the CPU or GPU.
  • the image analysis device 300 may further include an input unit (not shown).
  • the input unit is, for example, a device such as a keyboard or touch panel.
  • a predetermined command may be input from the input unit to the image processing unit 310 to cause the image processing unit 310 to perform signal processing.
  • the storage unit 320 is composed of storage devices such as RAM (Random Access Memory), SSD (Solid State Device), or HDD (Hard Disk Drive).
  • the storage unit 320 stores image signals before signal processing and image signals after signal processing. Further, the storage unit 320 stores the above-described sequence and the like.
  • the storage unit 320 may store information other than these, such as the result of visual inspection of the target object 600 .
  • the display unit 330 is a display device such as a liquid crystal display or an organic EL (Electro-Luminescence) display.
  • the display unit 330 displays the image of the object 600 after signal processing by the image processing unit 310 .
  • the display unit 330 may display an image of the object 600 before signal processing.
  • the display unit 330 may display information other than these, such as the result of the visual inspection of the object 600 .
  • the display unit 330 may be used as a touch panel and also used as an input unit.
  • FIG. 2A shows a schematic cross-sectional view of a main part of the illumination device
  • FIG. 2B shows a partially enlarged view of FIG. 2A
  • FIG. 2C shows a schematic plan view of the first surface light source.
  • the first surface light source 10 has at least a first light guide plate 11, a plurality of LEDs (light sources) 60, and a lid member 50.
  • the second surface light source 20 has at least a second light guide plate 21 and a plurality of LEDs 60 .
  • the third surface light source 30 has at least a third light guide plate 31 and a plurality of LEDs 60 .
  • the first to third fixtures 51 to 53 are used to arrange and assemble the first to third surface light sources 10, 20, 30 at respective predetermined positions. Note that the lid member 50 and the first to third fixtures 51 to 53 correspond to the housing.
  • Each of the first to third light guide plates 11, 21, 31 is a substrate made of a material transparent to illumination light, such as quartz glass or acrylic.
  • Each of the first to third light guide plates 11, 21, 31 has flat second surfaces 11b, 21b, 31b and first surfaces 11a, 21a, 31a facing the second surfaces 11b, 21b, 31b in the Z direction. ing.
  • the "first surface” refers to the surface from which the illumination light is emitted, that is, the surface on which the object 600 is arranged.
  • “Second surface” refers to the surface on which the camera 200 is arranged.
  • the first surfaces 11a, 21a, 31a are located below the second surfaces 11b, 21b, 31b in the Z direction.
  • the Z direction is the normal direction of the first surfaces 11a, 21a, 31a and the second surfaces 11b, 21b, 31b.
  • the second light guide plate 21 is larger than the first light guide plate 11, and the third light guide plate 31 is larger than the second light guide plate 21. Furthermore, in plan view, the outer circumference of the first light guide plate 11 is positioned inside the outer circumference of the second light guide plate 21, and the outer circumference of the second light guide plate 21 is positioned inside the outer circumference of the third light guide plate 31. are doing.
  • the first surface light source 10, the second surface light source 20, and the third surface light source 30 are superimposed in this order along the Z direction so that their central axes O1 to O3 are aligned.
  • the central axis O1 of the first surface light source 10 is a virtual axis passing through the center of the first light guide plate 11 and extending in the Z direction in plan view.
  • central axes O2 and O3 of the second and third surface light sources 20 and 30 pass through the respective centers of the second and third light guide plates 21 and 31 and extend in the Z direction in plan view. is the axis.
  • the central axis O1 corresponds to the optical axis of illumination light emitted from the first surface light source 10 .
  • each of the first to third light guide plates 11, 21, 31 is provided with optical path changing portions 12, 22, 32 therein.
  • the optical path changing portions 12, 22, and 32 allow the illumination light incident from the respective side surfaces of the first to third light guide plates 11, 21, and 31 and propagated thereinto to the respective first surfaces 11a, 21a, and 31a. Change the optical path to go.
  • the optical path changing portions 12, 22, 32 are formed, for example, by the method described below. However, the method of forming the optical path changing portions 12, 22, 32 is not particularly limited to this.
  • the first to third light guide plates 11, 21, and 31 are made of a glass material, for example, laser light is irradiated from the second surfaces 11b, 21b, and 31b to partially melt and sublimate the glass surface to form the recesses. to form Since the angle with respect to the illumination light is different on the surface of the concave portion, part of the light reflected by the concave portion is extracted to the outside of the light guide plate.
  • the structure of the optical path changing units 12, 22, and 32 is not particularly limited to this. As described above, any structure may be employed as long as the optical path can be changed so that the illumination light is directed to the first surfaces 11a, 21a, 31a inside the first to third light guide plates 11, 21, 31, respectively. The arrangement of the optical path changers 12, 22, 32 inside the first to third light guide plates 11, 21, 31 will be described later.
  • the side surface may be called "third surface".
  • the normal direction of the third surface intersects the normal direction of each of the first surfaces 11a, 21a, 31a and the second surfaces 11b, 21b, 31b, in this case, the Z direction.
  • the plurality of LEDs 60 are arranged at intervals along the outer peripheries of the first to third light guide plates 11, 21, 31, respectively. Moreover, as shown in FIGS. 2B and 2C, the plurality of LEDs 60 are mounted on the surface of the LED substrate 61 .
  • the LED substrate 61 is a printed wiring board having wiring (not shown) for power supply to the LEDs 60 formed on its surface. The power supply wiring is electrically connected to the lighting power source 400 .
  • the LED substrate 61 on which the LEDs 60 are mounted is held by the spacer 62, and further attached and fixed to the first to third light guide plates 11, 21, 31 by the first to third fixtures 51 to 53. be.
  • the distances between the first to third light guide plates 11, 21, 31 and each LED board 61 and the position of each LED board 61 with respect to the first to third light guide plates 11, 21, 31 are determined.
  • the plurality of LEDs 60 are each known white LEDs. Therefore, the illumination light emitted from each of the first to third surface light sources 10, 20, 30 is white light. However, the emission color of the LED 60 is not particularly limited to this. Depending on the material and shape of the target object 600, it can be changed as appropriate to perform a desired appearance inspection.
  • the illumination light may be infrared light that is not visible light.
  • the first to third fixtures 51 to 53 and the lid member 50 are light absorbing members made of a material that absorbs incident illumination light at a ratio equal to or greater than a predetermined rate.
  • the lid member 50 is a thin aluminum plate with an alumite-treated surface
  • the first to third fixtures 51-53 are aluminum moldings or assemblies with alumite-treated surfaces.
  • the first to third fixtures 51 to 53 and the lid member 50 absorb 90% or more of the incident illumination light (white light).
  • the absorption ratio of the illumination light is not particularly limited to this value, and can be appropriately changed according to the specifications required for the visual inspection.
  • the lid member 50 extends inward from the outer periphery of the first light guide plate 11 by a predetermined length so as to cover the second surface 11 b of the first light guide plate 11 .
  • the lid member 50 has an opening 50a (area marked with a dot pattern in FIGS. 2B and 2C).
  • the opening 50a is rectangular in plan view, but the shape is not particularly limited to that shown in FIG. 2C. For example, it may be circular, elliptical, or n-sided (where n is an integer of 4 or more).
  • the portion not covered with the lid member 50 may be called the first irradiation area 13 in plan view.
  • the first light guide plate 11 is rectangular, but this is also not particularly limited and can be changed as appropriate. For example, it may be circular or n-sided.
  • the lower part of the first fixture 51 is the outer edge part of the first surface 11 a of the first light guide plate 11 , i.e., a predetermined length from the outer periphery of the first light guide plate 11 It covers the part that goes inside. Further, when the first to third surface light sources 10, 20, and 30 are arranged in an overlapping manner, the lower portion of the first fixture 51 is the outer edge portion of the second surface 21b of the second light guide plate 21. covering the
  • the lower portion of the second fixture 52 covers the outer edge portion of the first surface 21 a of the second light guide plate 21 .
  • the lower portion of the second fixture 52 is the outer edge portion of the second surface 31b of the third light guide plate 31. covering the In other words, the first and second fixtures 51 and 52 and the lid member 50 cover the outer edges of the second surfaces 11b, 21b and 31b of the first to third light guide plates 11, 21 and 31, respectively. is provided.
  • the lower portion of the third fixture 53 covers the outer edge portion of the first surface 31 a of the third light guide plate 31 .
  • the third fixing member 53 extends inward from the outer periphery of the third light guide plate 31 by a predetermined length so as to cover the first surface 31 a of the third light guide plate 31 . is provided in That is, an opening 53a is formed in the lower portion of the third fixture 53. As shown in FIG.
  • the opening 53a is, for example, rectangular in plan view, but the shape is not particularly limited.
  • the openings 50a and 53a correspond to transmission portions.
  • a portion of the second light guide plate 21 that is covered with the lower portion of the first fixture 51 in a plan view may be referred to as a second irradiation region 23 .
  • a portion of the third light guide plate 31 that is covered with the lower portion of the second fixture 52 in a plan view may be referred to as a third irradiation region 33. .
  • the outer shape of the portion of the second surface 21b of the second light guide plate 21 that is not covered with the first fixture 51 may be substantially the same as the outer shape of the first irradiation area 13 described above.
  • the outer shape of the portion may differ from the outer shape of the first irradiation area 13, and may be n-sided, circular, or elliptical in plan view, for example.
  • the outer shape of the portion of the second surface 31b of the third light guide plate 31 that is not covered with the second fixture 52 may be substantially the same as or different from the outer shape of the first irradiation area 13.
  • it may be n-sided, circular, or elliptical in plan view.
  • both the second irradiation area 23 and the third irradiation area 33 are annular in plan view.
  • the second irradiation area 23 is positioned outside the first irradiation area 13 and the third irradiation area 33 is positioned outside the second irradiation area 23 when viewed from the central axes O1 to O3.
  • the outer edge portion of the second irradiation region 23 and the inner edge portion of the third irradiation region 33 partially overlap.
  • the visual inspection apparatus 500 of this embodiment can control which one of the first to third surface light sources 10, 20, and 30 emits the illumination light according to the visual inspection item.
  • illumination light may be directed toward the object 600 from all of the first to third surface light sources 10, 20, and 30 (see FIG. 4C, for example).
  • the surface of the object 600 A desired image may not be obtained due to uneven illumination light.
  • the object 600 It is possible to prevent the unevenness of the illumination light from occurring on the surface of the substrate and obtain a desired image.
  • optical path changing portions 12, 22, 32 are formed inside the first to third irradiation regions 13, 23, 33, respectively.
  • the first to third irradiation regions 13, 23, 33 are regions in which the optical path changing portions 12, 22, 32 are formed in the first to third light guide plates 11, 21, 31, respectively.
  • the first irradiation area 13 is arranged at a position passing through the central axis O1 of the first surface light source 10 .
  • the return light after the object 600 is irradiated with the illumination light passes through the first irradiation region 13 that is not covered with the lid member 50 or the first to third fixtures 51 to 53. and is incident on the camera 200 . Therefore, the image of the object 600 can be reliably acquired by the camera 200, and the surface state of the object 600 can be correctly evaluated.
  • the portions that function as prisms in the optical path changing portions 12 , 22 , 32 are actually opaque to the return light from the object 600 . Therefore, it is preferable that the portions functioning as prisms in the first irradiation area 13 are formed with a space therebetween in plan view. Moreover, it is preferable that the area of the portion functioning as a prism in the first irradiation region 13 is limited to a constant ratio smaller than the total area of the first irradiation region 13 in plan view. For example, in this embodiment, the area of the portion functioning as a prism is about 20% of the total area of the first irradiation area 13 .
  • the image of the object 600 can be reliably acquired by the camera 200 even if the optical path changing unit 12 is provided over the entire first irradiation area 13 .
  • the ratio is not particularly limited to this value. If the ratio is in the range of about 5% to 40%, a practical image of the target object 600 can be acquired in performing the appearance inspection.
  • the second surfaces 21b and 31b of the second irradiation region 23 and the third irradiation region 33 are covered with the first fixture 51 and the second fixture 52, respectively, so that the return light from the object 600 does not pass through. Structure. Therefore, in each of the second irradiation region 23 and the third irradiation region 33 , the area of the portion functioning as a prism with respect to the total area in plan view may be larger than the above-described proportion of the first irradiation region 13 .
  • the camera 200 is arranged so that the object 600 is in focus. That is, camera 200 is arranged such that the focal point of the lens provided in camera 200 is located on the surface of object 600 .
  • the optical path changing portion 12 formed in the first irradiation area 13 hardly appears in the image of the object 600 , and therefore does not significantly affect the image analysis of the object 600 .
  • the second irradiation area 23 and the third irradiation area 33 are positioned outside the object 600 in plan view. Illumination light emitted from each region has a spatial spread. Therefore, by appropriately setting the distance in the Z direction between the second irradiation area 23 or the third irradiation area 33 and the object 600, the object 600 can be irradiated with the illumination light. Similarly, by appropriately setting the sizes of the second irradiation region 23 and the third irradiation region 33 in the X direction and the Y direction with respect to the size of the object 600 in the X direction and the Y direction, the object 600 is irradiated with the illumination light. can do.
  • the optical path of the illumination light is changed by the optical path changing portion 12 formed in the first light guide plate 11 so that the optical axis of the illumination light substantially coincides with the central axis O1. emitted.
  • the illumination light has its optical path changed by the optical path changing portion 22 formed in the second light guide plate 21, and is inclined from the Z direction so as to travel along the extension line of the central axis O2 of the second light guide plate 21. It is emitted from the first surface 21a.
  • the illumination light has its optical path changed by the optical path changing portion 32 formed in the third light guide plate 31, and is inclined from the Z direction so as to travel along the extension line of the central axis O3 of the third light guide plate 31. It is emitted from the first surface 31a. Needless to say, the angle of the emission direction of the illumination light with respect to the central axes O2 and O3 is larger in the third surface light source 30 than in the second surface light source 20.
  • the antireflection coating 40 is provided on portions not covered by the fixtures 51 to 53 and the lid member 50 .
  • the antireflection coating 40 is made of a material having a reflectance of a predetermined value or less, for example, a reflectance of less than 4%, with respect to the return light of the illumination light and the illumination light reflected and scattered by the object 600 .
  • the illumination light emitted from each of the first to third light guide plates 11, 21, 31 to the outside is directed to the first to third light guide plates 11, 21, 31 can be prevented from receiving unnecessary reflection on the first surfaces 11a, 21a, 31a and the second surfaces 11b, 21b, 31b.
  • the illumination light emitted from the prism of the optical path changing unit 12 is reflected upward at the interface and directed toward the camera to hinder imaging when the object 600 is irradiated.
  • the return light of the illumination light that is reflected or scattered by the object 600 and returns to the camera 200 is unnecessary on the second surfaces 11b, 21b, 31b of the first to third light guide plates 11, 21, 31.
  • the return light of the illumination light can be reduced in loss when it is incident on the camera 200 after passing through the first to third light guide plates 11 , 21 and 31 . Therefore, a clear image of the object 600 can be acquired, and the surface state of the object 600 can be evaluated correctly.
  • the light emitted from the LED 60 is directed to the first surfaces 11a, 21a, and 31a by the optical path changing portions 12, 22, and 32.
  • the light paths are changed (reflected) as described above, and the target object 600 is irradiated with the light through the opening 53 a of the third fixture 53 .
  • the light applied to the object 600 is reflected by the object 600 and enters the camera 200 through the opening 53a of the third fixture 53 and the opening 50a of the cover member 50.
  • FIGS. 3A to 3C are schematic cross-sectional views of main parts of the illumination device when the object is irradiated with illumination light in the first to third illumination modes, respectively.
  • 4A to 4C show schematic diagrams of images of the object when the object is irradiated with the illumination light in the first to third illumination modes, respectively.
  • FIG. 5 shows the signal processing process of the image signal.
  • FIG. 6 shows a list of light and dark states of an image of an object due to differences in the physical state of the surface of the object and the illumination mode.
  • 3A to 3C illustration of the optical path changing portions 12, 22, 32 and the antireflection coating 40 is omitted.
  • the object 600 shown in FIGS. 4A to 4C has two metal patterns 620 provided on the base substrate 610 . Moreover, a rectangular resin pattern 630 made of white resin is provided on the two metal patterns 620 so as to straddle them. A circular pattern 631 exists on the resin pattern 630 . Of the two metal patterns 620, one surface has a hook-shaped flaw 621, and the other surface has a convex defect 623 with a substantially elliptical contour and a dirt 622 with a substantially triangular contour. ing.
  • the object 600 When performing a visual inspection of the object 600 using the visual inspection apparatus 500 shown in FIG. 1, the object 600 is irradiated with illumination light in the following three illumination modes. By doing so, it is possible to reliably acquire an image of a defect or the like to be detected according to the physical state of the surface of the object 600 .
  • the first surface light source 10 is operated to irradiate the object 600 with illumination light (first illumination mode).
  • the optical axis of the illumination light substantially coincides with the central axis O1.
  • the surface of the object 600 is irradiated so that the optical axis of the illumination light is orthogonal, and the return light reflected by the surface of the object 600 is mainly incident on the camera 200 .
  • portions where the physical state of the surface has a strong property of reflecting the illumination light appear bright, and other portions appear dark.
  • the outline of metal pattern 620 and convex defect 623 are clearly recognizable.
  • the scratches 621 and stains 622 on the metal pattern 620 look dark, but the background metal pattern 620 looks bright, so the visibility is rather improved.
  • the outline of the resin pattern 630 and the outline of the circular pattern 631 are not clearly visible.
  • the second surface light source 20 and the third surface light source 30 are not operating.
  • the return light reflected by the surface of the object 600 enters the second irradiation area 23 or the third irradiation area 33 , the return light is absorbed by the first fixture 51 or the second fixture 52 . Therefore, unnecessary propagation of return light is suppressed inside the second light guide plate 21 and the third light guide plate 31 .
  • the third surface light source 30 is operated to irradiate the object 600 with illumination light (second illumination mode).
  • the surface of the object 600 is obliquely irradiated with illumination light.
  • scattered light scattered on the surface of the object 600 is mainly incident on the camera 200 as returned light.
  • portions where the physical state of the surface has a strong tendency to scatter the illumination light appear bright, and other portions appear dark.
  • the outline of the resin pattern 630 and the outline of the circular pattern 631 can be clearly recognized.
  • the contour of the metal pattern 620 and the convex defect 623 are not clearly visible.
  • the metal pattern 620 serving as the background looks dark, the visibility of scratches 621 and stains 622 on the metal pattern 620 is lower than in the case shown in FIG. 4A.
  • the first surface light source 10 and the second surface light source 20 are not operating.
  • the return light scattered by the surface of the object 600 enters the second irradiation area 23 . Therefore, unnecessary propagation of return light is suppressed inside the second light guide plate 21 .
  • the return light is absorbed by the lid member 50 . Therefore, unnecessary propagation of return light is suppressed inside the first light guide plate 11 .
  • the illumination light includes a component that illuminates the surface of the object 600 so that the optical axis is perpendicular to the surface and a component that illuminates the surface obliquely. Therefore, the return light incident on the camera 200 is mainly composed of reflected light reflected by the surface of the object 600 and scattered light scattered by the surface of the object 600 . As a result, as shown in FIG. 6, portions where the physical state of the surface strongly reflects or scatters the illumination light appear bright, and other portions appear dark. For example, as shown in FIG.
  • the outline of metal pattern 620 and convex defect 623 are clearly recognizable.
  • the outline of the resin pattern 630 and the outline of the circular pattern 631 can be clearly recognized.
  • the background metal pattern 620 looks dark, the visibility of scratches 621 and stains 622 on the metal pattern 620 is lower than in the case shown in FIG. 4A.
  • the image processing unit 310 performs differential detection processing on pixel signals output from the imaging device of the camera 200 .
  • the amplitude of the pixel signal in other words, the signal strength can be doubled, and offset components such as common mode noise can be removed.
  • FIG. 6 shows an enlarged cross-sectional view of an optical path changing portion in the first light guide plate according to this embodiment.
  • the dashed line shows the light emitted from the LED 60 provided on the left side of the drawing.
  • the optical path changing section 12 has multiple prisms 70 .
  • a plurality of prisms 70 are formed on the second surfaces 11b of the first to third light guide plates 11 .
  • Each prism 70 is formed as a substantially conical (rotationally symmetrical) concave portion 75 having an opening 74 at the top of the drawing so as to be symmetrical with respect to the Z-axis (first direction).
  • An antireflection coating (AR coating) is applied to the surface of each prism 70 (recess 75).
  • the prism 70 (recess 75 ) has a first control surface 71 , a second control surface 72 and a bottom surface 73 .
  • the first control surface 71 is the surface of the prism 70 on the left side of the drawing, and reflects downward the light emitted from the LED 60 arranged on the left side of the drawing.
  • the second control surface 72 is a surface of the prism 70 on the right side of the drawing, and reflects downward the light emitted from the LED 60 arranged on the right side of the drawing.
  • the first control surface 71 and the second control surface 72 are formed as substantially flat surfaces forming a skirt angle ⁇ with respect to the X-axis. Also, the first control surface 71 and the second control surface 72 are formed to be symmetrical with respect to the Z axis.
  • the bottom surface 73 is a plane formed between the first control surface 71 and the second control surface 72 . As shown in FIG. 6, the bottom surface 73 is formed as a plane connecting the first control surface 71 and the second control surface 72 . As shown in FIG. 6, the bottom surface 73 is arranged in the center of the recess 75 in the X direction, and is formed so that its cross section is linear so as to match the X direction. In addition, the angle between the bottom surface 73 and the second surface 11 b of the first light guide plate 11 is smaller than the angle between the bottom surface 73 and the first control surface 71 . By forming the bottom surface 73 between the first control surface 71 and the second control surface 72, the distance between the first control surface 71 and the second control surface 72 in the X direction can be increased.
  • arrows indicate the light emitted from the LEDs 60 arranged on the left side of the drawing.
  • the light incident on the first control surface 71 does not enter the second control surface 72 .
  • the light incident on the first control surface 71 is incident on the second control surface 72 and directly incident on the camera 200 . can be deterred.
  • the first control surface 71, the second control surface 72 and the bottom surface 73 are coated with antireflection coating.
  • the optical path of the light emitted from the LED 60 when the antireflection coating is not applied to the second control surface 72 is indicated by a chain double-dashed line.
  • the second control surface 72 is not coated with an antireflection coating, part of the light emitted from the LEDs 60 will enter the camera 200 directly.
  • FIG. 7 is a diagram showing the light distribution portion distribution of the first surface light source according to this embodiment.
  • the distance in the X direction between the upper end of the first control surface 71 and the upper end of the second control surface 72 (the width of the opening 74 in the X direction) is the prism width
  • the X FIG. 4 is a diagram for explaining the relationship between the width of the prism, the width of the bottom surface, and the base angle ⁇ when the width in the direction is the width of the bottom surface;
  • the row direction indicates the set value of the base angle ⁇
  • the column direction indicates the set values of the prism width and the base width
  • the light distribution curve of the first surface light source 10 at each set value is illustrated. . Further, in FIG.
  • the amount of light output by the LED 60 is indicated as “output total luminous flux”, and the amount of light output by the first surface light source 10 upward 20° (within a range of ⁇ 10° with respect to the upper direction in the Z direction) is indicated as “clear light”.
  • 20° of the light output downward by the first surface light source 10, “120 mm below” incident on a 120 mm square area located 100 mm below, the S/N ratio of the first surface light source 10 ((first The amount of light output downward by the surface light source 10)/(the amount of light output upward by the first surface light source 10)) is indicated as "downward 120 mm/20° trivial light".
  • the antireflection coating (AR coating) is not applied to the prism 70, the length of one side of the first light guide plate 11 is 100 mm, the length of one side of the openings 51a and 53a is 70 mm, and the first light guide plate 11 has a thickness of 3 mm.
  • the object 600 is arranged at a position 98.5 mm below the first light guide plate 11 .
  • the object 600 can be effectively irradiated with light. Also, if the illuminance at 20° above the first surface light source 10 is low, direct incidence of light from the LED 60 on the camera 200 can be suppressed. That is, if the S/N ratio of the first surface light source 10 is high, it can be said that direct incidence of light from the LED 60 to the camera 200 can be suppressed while effectively irradiating the object 600 with light.
  • the S/N ratio of the first surface light source 10 increases as the bottom width increases.
  • the increase in the S/N ratio of the first surface light source 10 increases. . Therefore, by setting the width of the bottom surface to 25% or more, it is possible to effectively irradiate the object 600 with light and prevent the LED 60 from directly entering the camera 200 .
  • FIG. 8 is a diagram showing the light distribution portion distribution of the first surface light source according to this embodiment.
  • FIG. 8 differs from FIG. 7 in that the prism 70 is coated with an antireflection coating. Comparing FIG. 8 and FIG. 7, the S/N ratio of the first surface light source 10 is higher in FIG. Therefore, by applying an anti-reflection coating to the prism 70 , it is possible to effectively irradiate the object 600 with light and prevent the light from directly entering the camera 200 from the LED 60 .
  • the lighting device includes the LED 60 (light source), the first surface 11a that emits the light incident from the LED 60, and the first surface 11a that faces the first surface 11a to reflect and/or Alternatively, a first light guide plate 11 having a second surface 11b on which a plurality of refracting prisms 70 are arranged, the LED 60 and the first light guide plate 11 are housed, and light is emitted outside the first surface 11a and the second surface 11b. It comprises a cover member 50 having openings 50a and 53a (transmissive portions) for transmitting the light, and first to third fixtures 51 to 53 (casing).
  • the LEDs 60 emit light from at least two directions to the first light guide plate 11 .
  • Each prism 70 has a concave portion 75 that is symmetrical with respect to the Z direction (first direction) in which the first surface 11a and the second surface 11b face each other.
  • the concave portion 75 connects the first control surface 71 and the second control surface 72 to the first control surface 71 and the second control surface 72, which are substantially flat surfaces formed so as to be symmetrical to each other with respect to the Z direction. and a bottom surface 73 .
  • An antireflection coating is applied to the first control surface 71 and the second control surface 72 .
  • the distance between the first control surface 71 and the second control surface 72 in the X direction can be increased.
  • the light that has entered the first control surface 71 from the LED 60 is prevented from entering the second control surface 72, so that the light that has entered the first control surface 71 does not enter the second control surface 72.
  • direct incidence on the camera 200 can be suppressed.
  • Antireflection coating is applied to the first control surface 71 and the second control surface 72 .
  • the light incident on the first control surface 71 and the second control surface 72 is transmitted to the camera 200 side, so that it is possible to prevent the light from directly entering the camera 200 from the LED 60 .
  • the light incident on the first control surface 71 and the second control surface 72 from the LED 60 is more reflected in the direction toward the object 600. easier to do.
  • the illumination rate for the object 600 can be increased. Therefore, it is possible to irradiate the object with light at a high illumination rate while suppressing the amount of light that directly enters the camera from the light source (LED 60).
  • the concave portion 75 is rotationally symmetrical with respect to the Z direction.
  • the LEDs 60 emit light from four or more directions to the first light guide plate 11 .
  • the object 600 can be irradiated with less anisotropic light, and the amount of light can be increased.
  • the bottom surface 73 is a curved surface that forms a smaller angle with the second surface 11 b than the angle with the first control surface 71 . As a result, there is no sudden change in the angle of the bottom surface 73, and manufacturing irregularities are less likely to occur, so that the prism 70 can be produced by laser processing.
  • the bottom surface 73 of the prism 70 is formed to be planar, but the shape of the bottom surface 73 is not limited to this.
  • the bottom surface 73 may be formed in a curved shape that is recessed downward.
  • the bottom surface 73 of the prism 70 in this embodiment may have any shape as long as it is substantially flat such as a flat surface or a curved surface.
  • the term “substantially planar surface” refers to a surface having a substantially linear cross section.
  • First surface light source 11 First light guide plate 11a First surface 11b of first light guide plate Second surface of first light guide plate 12
  • Optical path changing unit 50 Lid member (casing) 51 first fixture (casing) 52 Second fixture (casing) 53 third fixture (casing) 60 LEDs (light source) 70 Prism 71 First control surface 72 Second control surface 73 Bottom surface 74 Opening 75 Concave portion 600 Object

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PCT/JP2022/046422 2021-12-24 2022-12-16 照明装置 WO2023120424A1 (ja)

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JP2008130248A (ja) * 2006-11-16 2008-06-05 Enplas Corp 面光源装置及びこれを備えた表示装置
TWI509327B (zh) * 2013-05-07 2015-11-21 Young Lighting Technology Inc 背光模組、顯示裝置及顯示方法
JP6478050B2 (ja) * 2015-05-15 2019-03-06 パナソニックＩｐマネジメント株式会社 面光源照明装置
CN205880454U (zh) * 2016-08-04 2017-01-11 扬升照明股份有限公司 背光模组及显示装置

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