Lighting equipment

Abstract

To provide a lighting device capable of increasing the amount of light reaching a line sensor without causing reflection of light from a light source, etc. and also achieving space saving while maintaining the advantages of doom type lighting as much as possible.SOLUTION: The lighting device includes: a plurality of light sources 10, 20 or a light-emitting face; and a light guide plate 30 into which light from the plurality of light sources 10, 20 or light-emitting face enters from an end face. On one face in a thickness direction of the light guide plate 30, a plurality of reflection parts 31 are provided for reflecting the light entering from the end face toward an irradiation position which the light guide plate 30 faces. An observation window 32 is provided in the light guide plate 30. A first ratio as a ratio of an area of the observation window 32 where the reflection parts 31 are provided to the total area of the observation window 32 is 2% or larger, and a second ratio as a ratio of an area of a part 33 other than the observation window 32 where the reflection parts 31 are provided, to the total area of the other part 33 is 1.2 times the first ratio.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a lighting device. [Background technology]

[0002] There is known a technique for illuminating an imaging line (observation position) of a line sensor with a dome-shaped illumination device (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-166865 A Summary of the Invention [Problem to be solved by the invention]

[0004] The dome-shaped lighting device of Patent Document 1 has a slit at the top of the reflecting dome that runs along the length of the line sensor, and the line sensor observes an object placed below the reflecting dome through the slit. The dome-shaped lighting device illuminates the observation position of the line sensor with light from various directions. This has the advantage of minimizing the shadowed areas of the object.

[0005] In addition, a slit is provided at the top of the reflective dome and the line sensor is placed directly above the slit, which has the advantage that even if the target is a flat plate or the like with a mirror-like upper surface, the inner surface of the reflective dome and the LED light source are not reflected on the mirror-like upper surface of the target when viewed from the line sensor.

[0006] However, when the inner surface of the reflective dome or the LED light source is not reflected on the top surface of the target, which is a mirror surface when viewed from the line sensor, it is difficult for the light from the reflective dome to reach the line sensor. In other words, because there is a slit at the top end of the reflective dome, light is irradiated obliquely from the reflective dome onto the observation position of the line sensor, and the obliquely irradiated light is specularly reflected by the top surface of the target, which is a mirror surface. For this reason, there may be cases where the amount of light is insufficient when observing the target with the line sensor.

[0007] Additionally, the reflector dome may be large in order to provide a sufficient amount of light to the subject from multiple directions.

[0008] The present invention has been made in consideration of the above circumstances, and aims to provide an illumination device that maintains the advantages of dome-type illumination as much as possible, while increasing the amount of light that reaches the line sensor without causing reflections of light sources, etc., even when an object having a mirror-like upper surface is observed with the line sensor, and that also enables space saving. [Means for solving the problem]

[0009] In order to solve the above problem, an illumination device according to one aspect of the present invention includes a plurality of light sources arranged in parallel in an X direction or a light-emitting surface having a longitudinal direction in the X direction, and a light guide plate having a longitudinal direction in the X direction and having light from the plurality of light sources or the light-emitting surface enter from an end face in a Y direction perpendicular to the X direction, wherein one face in a thickness direction of the light guide plate is provided with a plurality of reflecting portions that reflect the light entering from the end face toward an irradiation position facing the light guide plate, and the light guide plate is provided with an observation window having a longitudinal direction in the X direction that enables the irradiation position to be observed with a line sensor via the light guide plate, and a first ratio that is a ratio of an area of ​​the observation window where the reflecting portions are provided to an entire area of ​​the observation window is 2 % or more, and a second ratio, which is the ratio of the area of ​​the other parts of the light guide plate other than the observation window where the reflective portion is provided to the entire area of ​​the other parts, is 1. 2 More than double.

[0010] In this embodiment, since the observation window is also provided with a reflector, when an object is observed by a line sensor through the observation window, light is also irradiated onto the object from the observation window. That is, the light supplied from the observation window to the object is supplied in the observation direction of the line sensor toward the object. Therefore, when an object having a glossy upper surface such as a mirror surface is observed by the line sensor, the amount of light supplied from the object to the line sensor is greater than that of conventional dome lighting. Furthermore, light is supplied to the target from reflecting portions other than the observation window, and light is supplied to the observation position of the line sensor from various directions. Effect of the Invention

[0011] According to the present invention, while maintaining the advantages of dome-shaped lighting as much as possible, when an object having a glossy upper surface such as a mirror surface is observed with a line sensor, it is possible to increase the amount of light reaching the line sensor without causing reflections of light sources, etc., and also to achieve space saving. [Brief description of the drawings]

[0012] [Figure 1] 1 is a plan view of an illumination device according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a side view showing a state in which the lighting device of the present embodiment is in use with a fixing member removed. [Diagram 3] FIG. 2 is a front view of the lighting device according to the embodiment. [Figure 4] FIG. 2 is a side view of the lighting device according to the embodiment. [Diagram 5] FIG. 2 is a plan view of the lighting device of the present embodiment with a fixing member removed. [Figure 6] 5 is a conceptual diagram showing the function of a reflecting portion of a light guide plate of the lighting device of the present embodiment. FIG. [Figure 7] 5 is a conceptual diagram showing the function of a reflecting portion of a light guide plate of the lighting device of the present embodiment. FIG. [Figure 8] 13 is a conceptual diagram of a light guide plate showing a modified example of the lighting device of the present embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] An illumination device according to one embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 2, this lighting device illuminates an object W to be observed (inspected) by a line sensor S. As shown in FIG. 1, this lighting device has a plurality of first light sources 10 arranged in a predetermined direction (X direction in FIG. 1) and a plurality of second light sources 20 arranged in the predetermined direction, and in this embodiment, each of the light sources 10 and 20 is an LED element such as a chip-type LED or a bullet-type LED. The plurality of light sources 10 are arranged at intervals from each other in the X direction, and the intervals are several mm, tens of mm, etc. The plurality of light sources 20 are also arranged at intervals from each other in the X direction. In one example, as shown in FIG. 2, the object W is transported in a Y direction perpendicular to the X direction by a conveyor CV.

[0014] This lighting device receives light from a plurality of first light sources 10 and light from a plurality of second light sources 20. vinegar In this embodiment, the light guide plate 30 is a flat plate made of transparent plastic. The light guide plate 30 may be made of other well-known materials such as glass. 1, in this embodiment, the predetermined direction is referred to as the X direction, and the direction perpendicular to the X direction in which the light guide plate 30 extends is referred to as the Y direction. Also, as shown in FIGS. 1 and 2, the direction perpendicular to the X direction and the Y direction is referred to as the Z direction.

[0015] Light from the multiple first light sources 10 enters the light guide plate 30 from one end surface 30a of the light guide plate 30 in the Y direction. Enter The light from the plurality of second light sources 20 enters the light guide plate 30 from the other end surface 30b in the Y direction of the light guide plate 30. enter . As shown in FIGS. 2 and 5, a plurality of first light sources 10 are mounted on a first body 11, and a plurality of second light sources 20 are mounted on a second body 21. As shown in FIG.

[0016] In one example, a plurality of first light sources 10 are attached to one end surface of the first body 11 on the light guide plate 30 side in the Y direction. A pair of protrusions 11a protruding in the Y direction is provided on the one end surface side of the first body 11. The pair of protrusions 11a are spaced apart from each other in the Z direction, and one end of the light guide plate 30 in the Y direction is disposed between the pair of protrusions 11a. In this embodiment, each protrusion 11a is provided over substantially the entire first body 11 in the Y direction. The pair of protrusions 11a positions the light guide plate 30 with respect to the first body 11 at least in the Z direction.

[0017] A plurality of second light sources 20 are attached to one end face of the second body 21 on the light guide plate 30 side in the Y direction, and the second body 21 is also provided with a pair of protrusions 21a similar to the first body 11. As shown in FIGS. 2 and 4, heat dissipation portions 11b, 21b are formed at the ends of the first body 11 and the second body 21 opposite the light guide plate 30 in the Y direction.

[0018] As shown in Figs. 1, 3, and 5, fixing members 40 are attached to one end and the other end in the X direction of the first and second bodies 11 and 21. One fixing member 40 is fixed to one end in the X direction of the first body 11 by a fastening member 41 such as a bolt, and is also fixed to one end in the X direction of the second body 21 by a fastening member 41. The other fixing member 40 is fixed to the other end in the X direction of the first body 11 by a fastening member 41, and is also fixed to the other end in the X direction of the second body 21 by a fastening member 41. Each fixing member 40 restricts the movement of the light guide plate 30 in the X direction and connects the first body 11 and the second body 21. With this configuration, the light guide plate 30 can be easily and reliably attached to the first and second bodies 10 and 20. With the above configuration, it is possible to easily and reliably manufacture this lighting device having different dimensions in the X direction, which is useful for flexibly responding to the demands of various customers who have different inspection objects, inspection conditions, etc.

[0019] As shown in FIG. 6, a plurality of reflecting portions 31 are provided on one surface 30c in the thickness direction of the light guide plate 30. In this embodiment, each reflecting portion 31 is a convex lens protruding from the one surface 30c. FIG. 6 shows one ideal shape of each reflecting portion 31. As shown in FIG. 6, each reflecting portion 31 reflects light from each light source 10, 20 in the light guide plate 30 toward an irradiation position facing the light guide plate 30 via the other surface 30d in the thickness direction of the light guide plate 30. Note that FIG. 6 is a schematic diagram for illustrating the function of the reflecting portion 31, and in FIG. 6, the thickness dimension of the light guide plate 30 is drawn smaller than the size of the reflecting portion 31.

[0020] Each reflective portion 31 can be formed by, for example, inkjet printing using a transparent ultraviolet curing plastic. The multiple reflective portions 31 are arranged at intervals DT in both the X and Y directions, and the intervals DT are, for example, 85 μm.

[0021] 1 and 2, in this embodiment, the center side in the Y direction of the light guide plate 30 functions as an observation window 32, and the observation window 32 has a longitudinal direction in the X direction. In this embodiment, the observation window 32 is provided over the entire light guide plate 30 in the X direction, but the range of the observation window 32 in the X direction may correspond to the observation range of the line sensor. The dimension of the observation window 32 in the Y direction is preferably 2 cm or less, but in this embodiment, the dimension of the observation window 32 in the Y direction is 1 cm or less.

[0022] The observation window 32 is also provided with the plurality of reflecting portions 31. The first diameter (diameter D shown in FIG. 6) of the observation window 32 is preferably 41 μm or less, more preferably 36 μm or less, and 32 μm in the present application. That is, in the observation window 32, the first ratio, which is the ratio of the area in which the reflecting portions 31 are provided to the entire area of ​​the observation window 32, is preferably 18% or less. The first ratio is more preferably 14% or less, and is about 11% in the present embodiment. If the first ratio is higher than the above ratio, when the object W is observed through the observation window 32 by the line sensor as shown in FIG. 2, the image obtained may become unclear. It is preferable that the first ratio is 2% or more. If the first ratio is less than 2%, the effect described below is often not obtained, but it may be usable depending on the observation conditions, object, etc. In the present embodiment, the reflecting portions 31 of the observation window 32 are evenly provided, but the distribution of the reflecting portions 31 may be uneven.

[0023] Here, when forming each reflecting portion 31, there are cases where a portion is formed that does not function as a convex lens that directs the light to the irradiation position. For example, as shown in FIG. 7, when a portion 31a of the reflecting portion 31 is formed thin along the one surface of the light guide plate 30 and the portion 31a is substantially flat, the reflecting portion does not function as a convex lens. In this case, as shown in FIG. 7, the area of ​​the portion AR of the convex lens that directs the light to the irradiation position is used to calculate the first ratio. A similar calculation is performed for the second ratio described below. Also, as shown in FIG. 7, even if the reflecting portion 31 has a single or multiple unique portions 31b that have different shape characteristics from other portions, or even if the reflecting portion 31 is not a smooth convex lens as a whole, it can be said to be a reflecting portion 31 as long as it has the function of directing the light to the irradiation position as a whole.

[0024] On the other hand, the second ratio, which is the ratio of the area where the reflecting portion 31 is provided in the other portion 33 other than the observation window 32 of the light guide plate 30 to the entire area of ​​the other portion 33, is preferably 1.5 times or more, more preferably 2 times or more, relative to the first ratio. When the first ratio is 10% or more, the effect described below may be achieved if the second ratio is 1.2 times or more relative to the first ratio. In this embodiment, the diameter of each reflecting portion 31 of the observation window 32 is 32 μm, so the second diameter (diameter D shown in FIG. 6) of each reflecting portion 31 is preferably 45 μm or more. In this embodiment, the second diameter is 62 μm, and the second ratio is about 42%. If the second ratio is 5% or more, the present illumination device can be realized, and it is preferably 15% or more, and if the amount of light is increased further, it is preferably 20% or more, and if the amount of light is further increased, it is preferably 25% or more. Even if the second ratio is less than 15%, inspection may be possible without problems depending on the purpose of observation. In this embodiment, the reflective portions 31 of the other portion 33 are evenly provided, but there may be a bias in the distribution of the reflective portions 31. In this embodiment, the dimension of the other portion 33 in the Y direction is 5 cm or more, but if the distance to the irradiation position is short, the same effect may be obtained if the dimension of the other portion 33 in the Y direction is 1 cm or more.

[0025] In some cases, the reflecting portions 31 are not uniformly distributed, making it difficult to confirm the ratio of the entire observation window 32 or the entire other portion 33. In this case, the first ratio can be determined by calculating the ratio of the area of ​​the reflecting portions 31 to the area of ​​each of multiple locations on the observation window 32, and averaging the ratios calculated at the multiple locations. The same applies to the second ratio. It is also possible to change the first ratio and the second ratio by changing the distance DT between the reflecting portions 31.

[0026] 2, a known line sensor S is disposed on the one surface 30c side of the light guide plate 30, and obtains an image of the target W at the irradiation position on the other surface 30d side of the light guide plate 30. Note that the line sensor S is naturally disposed along the observation window 32.

[0027] When the lighting device having the above configuration is used, more light reaches the line sensor S. In particular, light is also irradiated from the observation window 32 toward the irradiation position. The light from the light sources 10 and 20 travels through the light guide plate 30 as light ray trajectories L1, L2, L3, and L4 shown in FIG. 6, and some of the light ray trajectories L1, L2, L3, and L4 are reflected by the reflecting section 31 toward the irradiation position. A part of the light ray trajectories L4 travels approximately perpendicular to the other surface 30d of the light guide plate 30. Approximately perpendicular means, for example, that the angle between the other surface 30d and the light ray L4 is 80° or less, more preferably 85° or less. When the light guide plate 30 is made of a plastic material, the critical angle is 45° or less, and light that enters the reflecting section 31 at an angle exceeding the critical angle is reflected.

[0028] In this way, when the light reflected by the observation window 32 travels approximately perpendicular to the other surface 30d of the light guide plate 30, observation, inspection, etc. using the line sensor S may be accurate when the object W is glossy. Also, when electronic components or the like protrude from the surface of the object W, shadows caused by the electronic components are unlikely to be formed. In this way, this embodiment is effective in reducing changes in illuminance of the observation line due to the shape and gloss of the surface of the object W.

[0029] Furthermore, by reflecting light toward the target W at the position of the observation window 32, more light reaches the line sensor S for various types of target W, which is advantageous in terms of speeding up the inspection and improving the inspection accuracy. Also, unlike a case where the reflection unit 31 is not provided on the observation window 32, light is also irradiated onto the target W from a direction along the optical axis of the line sensor S, and the image obtained by the line sensor S differs from a case where the reflection unit 31 is not provided on the observation window 32. This results in differences in the brightness and appearance of the target W in the image, which can lead to improved inspection accuracy depending on the type of target W.

[0030] In addition, the observation position of the line sensor S is also illuminated with light from the other portion 33. Therefore, the target W at the observation position (illumination position) is illuminated from various directions, and the same effect as that of conventional dome-type lighting can be obtained. In other words, the same effect as that of dome-type lighting can be achieved in a small space.

[0031] When the second ratio is 1.5 times or more as large as the first ratio, the object W can be observed well due to a balance between the amount of light irradiated from the optical axis direction of the line sensor S, the amount of light irradiated from the other portion 33, and the clarity of the image obtained by the line sensor S. Note that, when the second ratio is 2.5 times or more or 3 times or more as large as the first ratio, as in this embodiment, the object W can often be observed better. In addition, when the first ratio is 10% or more, if the second ratio is 1.2 times or more the first ratio, the absolute value of the difference between the first ratio and the second ratio is 2% or more. In this case, too, the observation of the object W is often improved.

[0032] The position of the observation window 32 in the light guide plate 30 can be set arbitrarily. For example, it is possible to provide the observation window 32 at one end side of the light guide plate 30 in the Y direction, and provide the other portion 33 only on the other end side of the observation window 32 in the Y direction. Alternatively, it is possible to provide the observation window 32 at one end side of the light guide plate 30 in the Y direction, and provide the other portion 33 on both sides of the observation window 32 in the Y direction. These arrangements are effective when the object W can be seen better by irradiating more light from one side.

[0033] It is also possible to provide a plurality of observation windows 32 in the light guide plate 30 at intervals in the Y direction. Furthermore, the second ratio of the other portion 33 on one side in the Y direction with respect to the observation window 32 may be different from the second ratio of the other portion 33 on the other side in the Y direction. For example, the second ratio on one side may be 1.2 times or more, preferably 1.5 times or more, of the second ratio on the other side. This configuration is useful when inspecting an object W that is easier to observe with stronger light from one side in the Y direction.

[0034] Furthermore, it is useful that the illumination device has a structure having a plurality of types of light guide plates 30 and is configured to be able to replace the light guide plate 30 with another type of light guide plate 30 depending on the object to be inspected. In this embodiment, the light guide plate 30 can be replaced by attaching and detaching the fixing member 40.

[0035] It is also possible to configure the other portion 33 so that the density of the reflective portions 31 gradually increases toward the observation window 32 side. In this case, more light travels from the vicinity of the observation window 32 toward the irradiation position in the other portion 33. It is also possible to distribute the reflective portions 31 in other manners in the other portion 33. In the other portion 33, it is also possible to make the density of the reflecting portions 31 closer to the observation window 32 higher than the density of the reflecting portions 31 farther from the observation window 32. In this case, even if the observation window 32 is not provided with a reflecting portion 31, more light will travel from the line sensor S toward the irradiation position. Even when this configuration is used, the object W may be observed well depending on the object W, the purpose of observation, etc.

[0036] 8, it is also possible to provide a reflective portion 34, which is a recess, on one surface 30c in the thickness direction instead of the reflective portion 31. Even in this case, each reflective portion 34 reflects the light from the light sources 10 and 20 toward the irradiation position. The reflective portion 34 may be a cone-shaped recess, a pyramid-shaped recess, a recess in the shape of a part of a sphere, or a recess in any other shape. Alternatively, each reflecting portion 31 can be formed by attaching a reflecting member such as a small metal member to one surface 30c of the light guide plate 30 in the thickness direction.

[0037] Also, a reflective sheet may be placed in contact with or close to the surface 30c of the other portion 33 on one side in the thickness direction, together with the reflective portions 31, 34, or without the reflective portions 31, 34. The reflective sheet may be any known sheet that reflects light, such as a white sheet such as paper, or a sheet having a metallic luster such as aluminum foil. As in the case where the reflective portions 31, 34 and the unevenness due to roughening treatment or the like are provided on the other portion 33 on the surface 30c on one side in the thickness direction, enter When light leaks from one surface 30c in the thickness direction, the same effect can be achieved as when the reflecting portions 31, 34 are provided in the other portion 33. When a reflecting sheet is provided in the other portion 33 together with the reflecting portions 31, 34, etc., the amount of light at the irradiation position increases.

[0038] Also, instead of the plurality of first light sources 10, a light guide plate 30 is arranged along an end surface 30a of the light guide plate 30, and emits light from the end surface 30a into the light guide plate 30. put in A light emitting surface may be provided. The light emitting surface may be another light guide plate arranged along the end surface 30a. In this case, light is introduced into the other light guide plate, and the light is emitted from a surface along the end surface 30a of the other light guide plate. A similar light emitting surface may be provided instead of the multiple second light sources 10. Furthermore, each of the first light sources 10, 20 may be the tip of an optical fiber.

[0039] In addition, a plurality of light sources 10, 20 arranged in parallel in the X direction or a light emitting surface having a longitudinal direction in the X direction, and end faces 30a, 30b in a Y direction having a longitudinal direction in the X direction and in which light from the plurality of light sources 10, 20 or the light emitting surface is perpendicular to the X direction To and a light guide plate 30 on which the light is incident, the light guide plate having the end surface on one surface in the thickness direction. To A lighting device is also conceivable in which a plurality of reflecting portions 31, 34 that reflect the incident light toward an irradiation position facing the light guide plate are provided, the light guide plate 30 is provided with an observation window 32 that is an observation window that allows the irradiation position to be observed by a line sensor S through the light guide plate 30 and has a longitudinal direction in the X direction, the reflection portions 30a, 30b are not provided in the observation window, and the reflection portions 31, 34 are provided in a portion 33 other than the observation window 32 in the light guide plate 30. The area in which the reflection portions 31, 34 are provided in the other portion 33 is in accordance with the second ratio described above. In other words, the area in which the reflection portions 31, 34 are provided in the other portion 33 is 10% or more of the total area of ​​the other portion 33. It is also possible to form the observation window 32 by cutting out a portion of the light guide plate 30 that corresponds to the observation window 32. In this case, too, depending on the object W and the purpose of observation, it may be possible to observe the object W well. Also in this case, the object W at the observation position (illumination position) is illuminated from various directions, and the same effect as that of conventional dome-type lighting can be obtained. In other words, the same effect as that of dome-type lighting can be achieved in a small space. [Explanation of symbols]

[0040] 10...first light source, 20...second light source, 30...light guide plate, 30a...one end surface in the Y direction, 30b...the other end surface in the Y direction, 31...reflecting portion, 32...observation window, 33...other portion, 34...reflecting portion, S...line sensor, W...target

Claims

1. A plurality of light sources arranged in an X direction or a light emitting surface having a longitudinal direction in the X direction; a light guide plate having a longitudinal direction in the X direction, and into which light from the plurality of light sources or the light emitting surface enters from an end surface in a Y direction perpendicular to the X direction; a plurality of reflecting portions are provided on one surface of the light guide plate in a thickness direction thereof to reflect the light entering from the end surface toward an irradiation position facing the light guide plate; an observation window that allows the irradiation position to be observed by a line sensor through the light guide plate and has a longitudinal direction in the X direction is provided in the light guide plate; a first ratio, which is a ratio of an area of ​​the observation window where the reflection portion is provided to a total area of ​​the observation window, is 2% or more; a second ratio, which is a ratio of an area of ​​a portion of the light guide plate other than the observation window where the reflective portion is provided to a total area of ​​the other portion, is 1.2 times or more as large as the first ratio.

2. The lighting device of claim 1 , wherein the second percentage is greater than or equal to 5%.

3. The illumination device according to claim 1 , wherein each of the reflecting portions is a lens protruding from the light guide plate.

4. 4. The lighting device according to claim 1, further comprising a reflective sheet in contact with or adjacent to the other portion of the one surface in the thickness direction.

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