JP3726150B2 - Micro-area illumination device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention illuminates a target component in a soldering appearance inspection apparatus that inspects the state of a soldered part such as an electronic component mounted on a printed circuit board, or illuminates the sample when observing the sample with a microscope. In particular, the illumination device for a fine area used in the case of, for example, maintains a compact size of the device, has a high transmittance of the light irradiated to the object, and diffuses with high efficiency, and uniform illumination light from the center to the periphery The present invention relates to a lighting device of a fine area that can be made.
[0002]
[Prior art]
For example, when light is directly emitted from a single light emitting diode (hereinafter referred to as “LED”) as a light emitter, the intensity distribution of the illumination light at that time is as shown in FIG. In addition, when a convolved light generated from a plurality of LEDs is directly irradiated onto an object to be illuminated, a line image intensity distribution for viewing a part of the light is as shown in FIG. When a fine region is illuminated with such direct illumination light, in the intensity distribution or line image intensity distribution shown in FIG. 17 (a) or (b), the luminance is abrupt in the horizontal axis direction (x coordinate). A curve is drawn, and a large luminance difference appears between the center and the periphery. Therefore, there is a difference in brightness between the central part and the peripheral part of the object to be illuminated, and for example, a required inspection cannot be performed with high accuracy.
[0003]
On the other hand, a conventional illumination device for a fine area, for example, an illumination device for a soldering appearance inspection device, as disclosed in Japanese Patent Application Laid-Open No. 7-243986, has a disk-shaped mounting member having a photographing hole at the center. A large number of light emitters (LEDs) are arranged concentrically around the photographing hole on the lower surface side of the light emitter, and the light emitting direction of the large number of light emitters is below the light emitters for photographing the mounting member. A light diffusing smoke plate having through holes corresponding to the holes is attached, and the light emitted from the plurality of light emitters is diffused by the smoke plate to illuminate the target component. As a result, the illumination light with respect to the object can be made uniform to some extent.
[0004]
[Problems to be solved by the invention]
However, in such a conventional fine area illumination device, the smoke plate diffuses light emitted from a number of light emitters to illuminate the target part. In the line image intensity distribution shown, it is possible to suppress a steep curve and obtain a flat distribution characteristic. However, since the smoke plate is made of a circular plate made of, for example, translucent milky white plastic or glass, the light transmittance is somewhat low. The utilization efficiency of the irradiation light from the said light-emitting body may fall. Therefore, the intensity of light generated by the light emitter must be increased to some extent, and the lifetime of the light emitter may be reduced. Further, in the light diffusion by the smoke plate, the direction component of the transmitted light is almost lost, and the illumination light cannot be irradiated to the object at a certain angle.
[0005]
Therefore, the present invention addresses such problems and maintains the compactness of the apparatus while diffusing the light irradiated to the object with high transmittance and high efficiency and illuminating light from the center to the periphery. An object of the present invention is to provide a lighting device for a fine region that can be made uniform.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, an illumination device for a fine region according to a first invention includes a mounting member having a through hole for observing an object at a central portion, and the through hole on one side of the mounting member. A light emitting body provided in a ring shape as the center, and a portion corresponding to the through hole of the mounting member formed in parallel with a plurality of cylindrical lenses provided on one plane provided in the light irradiation direction of the light emitting body Includes a first lenticular lens that also has a through hole and scatters incident light, and is provided in close contact with one side of the first lenticular lens, and is configured similarly to the first lenticular lens and its cylindrical A second lenticular lens arranged such that the lens arrangement direction intersects the cylindrical lens arrangement direction of the first lenticular lens, and the second wrench A Fresnel lens that is provided close to the downstream side of the optical path of the modular lens and that also has a through hole at a portion corresponding to the through hole of the mounting member and guides light transmitted through the first and second lenticular lenses to the rear. Is provided.
[0007]
The Fresnel lens functions as a positive focus lens as a whole.
[0008]
The illumination device for a fine region according to the second invention is provided in a ring shape with a through hole for observing an object at the center and a ring surface around the through hole on one side of the mounting member. The light emitting body is provided in the vicinity of the light emitting body in the light irradiation direction of the light emitting body, and the portion corresponding to the through hole of the mounting member also has a through hole, and the irradiation light of the light emitting body is rearward. A first Fresnel lens that leads to the first Fresnel lens and the first Fresnel lens that is provided close to the downstream side of the optical path of the first Fresnel lens and that has a through hole in a portion corresponding to the through hole of the mounting member. And a second Fresnel lens that refracts the light transmitted through the lens parallel to the central portion.
[0009]
The first Fresnel lens functions as a negative focus lens as a whole.
[0010]
Furthermore, the illumination device for a fine area according to the third invention is provided in a ring shape with a through hole for observing the object at the center, and on the one side of the mounting member with the through hole as a center. A light-emitting body, a cylindrical lens provided in a ring shape corresponding to the position of the light-emitting body in the light irradiation direction of the light-emitting body, and guiding the irradiation light backward, and on the downstream side of the optical path of the cylindrical lens In addition, a portion corresponding to the through hole of the mounting member is provided with a Fresnel lens that similarly has a through hole and refracts the light transmitted through the cylindrical lens in parallel toward the central portion.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a cross-sectional explanatory view showing an embodiment of an illumination device for a fine region according to the first invention. The example of FIG. 1 shows an illuminating device that illuminates a target component 2 in a soldering appearance inspection device that inspects the state of a soldering part such as an electronic component mounted on a printed circuit board 1, for example. As shown in FIG. 1, the mounting member 3, the light emitter 4, the first lenticular lens 5a, the second lenticular lens 5b, and the Fresnel lens 6 are provided.
[0012]
The mounting member 3 is a member for mounting and wiring the light emitter 4 of the lighting device, and is formed in a disk shape having an appropriate diameter (for example, 200 mm) as shown in FIG. A through hole 7 for observing the target component 2 such as an electronic component mounted on the printed circuit board 1 to be inspected from above is formed. In FIG. 1, reference numeral 8 denotes an imaging device such as a television camera or a CCD camera that takes an image for visual inspection of the target component 2 mounted on the printed circuit board 1. A lens for imaging the reflected light on the imaging device 8 is shown.
[0013]
A large number of light emitters 4 are mounted in the same plane on one side (for example, the lower surface side) of the mounting member 3. The light emitter 4 emits illumination light for illuminating the target component 2 in order to inspect the state of a soldered part such as an electronic component mounted on the printed circuit board 1, and is composed of, for example, a light emitting diode (LED). As shown in FIG. 2, a plurality of concentric rings are arranged in a ring shape around the through hole 7.
[0014]
A first lenticular lens 5 a is provided in the light irradiation direction of the light emitting body 4, that is, on the lower side. The first lenticular lens 5a is made to enter and scatter the light emitted from the light emitter 4, and as shown in FIG. 3, a large number of cylindrical lenses (rod-shaped rods formed in a kamaboko shape on one plane). Lenses 10, 10,... Are arranged in parallel, and are formed in a disk shape having the same size as the mounting member 3 shown in FIG. 1 as a whole, and correspond to the through-hole 7 of the mounting member 3. Similarly, a through-hole 11 is formed in the part to be performed. As shown in FIG. 3, the first lenticular lens 5a is characterized by the fact that light emitted from a single light emitter 4 as a point light source is transmitted, so that the object surface 12 has a large number of cylindrical lenses 10 as described above. , 10,... Has a characteristic that a light irradiation surface 13 extending in a strip shape is formed. The first lenticular lens 5a is provided close to the light emitter 4 at a predetermined interval (for example, an interval of about 10 mm) in FIG. This is because the diffusion effect by the first lenticular lens 5a is weakened if it is too close, and the device itself becomes large if it is too far away.
[0015]
A second lenticular lens 5b is provided in close contact with one side of the first lenticular lens 5a. The second lenticular lens 5b is for entering and scattering the light emitted from the first lenticular lens 5a. As shown in FIG. 4, a large number of cylindrical lenses 10, 10,. Are arranged in parallel and configured in the same manner as the first lenticular lens 5a. As shown in FIG. 1, a through hole 14 is formed in a portion corresponding to the through hole 7 of the mounting member 3, and the cylindrical lens is formed. Are arranged perpendicular to the arrangement direction of the cylindrical lenses 10, 10,... Of the first lenticular lens 5a. The characteristics of the second lenticular lens 5b are exactly the same as those of the first lenticular lens 5a shown in FIG. 3, and as shown in FIG. 4, the first lenticular lens 5a, the second lenticular lens 5b, Are arranged so that the arrangement directions of the respective cylindrical lenses 10, 10,... Are orthogonal to each other, so that the light emitted from one light emitter 4 as a point light source is transmitted to the object plane 12. A square light irradiation surface 15 is formed. It is preferable that the arrangement directions of the cylindrical lenses 10, 10,... Of the first lenticular lens 5 a and the second lenticular lens 5 b are orthogonal to each other. The diffusion effect may be adjusted.
[0016]
In this state, the illumination light emitted from the ring-shaped light emitter 4 configured as shown in FIGS. 1 and 2 is on the object surface 12 shown in FIG. 4, and the intensity distribution is as shown in FIG. The line image intensity distribution is as shown in FIG. As is clear from FIG. 6, the light scattered through the first lenticular lens 5a and the second lenticular lens 5b combined as shown in FIG. 4 has a fairly flat line image intensity distribution. Thus, a fairly uniform luminance distribution can be formed on the object plane 12.
[0017]
A Fresnel lens 6 is provided close to the downstream side of the optical path of the second lenticular lens 5b. The Fresnel lens 6 guides the light transmitted through the first lenticular lens 5a and the second lenticular lens 5b to the rear, and a plurality of prisms having different refraction angles as shown in FIG. Are arranged in concentric circles and are formed in a disk shape as large as the mounting member 3 shown in FIG. 1 as a whole, and the portion corresponding to the through hole 7 of the mounting member 3 is also a through hole. 16 is formed. In the example of FIG. 7, the Fresnel lens 6 functions as a plus-focus lens as a whole.
[0018]
In this state, the illumination light irradiated from the ring-shaped light emitter 4 configured as shown in FIGS. 1 and 2 is combined with the first lenticular lens 5a and the second lenticular lens 5a as shown in FIG. The light scattered through the lenticular lens 5b is further transmitted through the plus-focus Fresnel lens 6 shown in FIG. 7 and guided backward, thereby having a flat line image intensity distribution as shown in FIG. Thus, a uniform luminance distribution can be formed on the irradiation target surface. Thereby, the illumination light irradiated to the target component 2 shown in FIG. 1 can be made uniform. Here, the light quantity uniformity by the lenticular lens is high, and the target part 2 is illuminated more brightly by condensing the uniformed light at the central part, which is the inspection part, using the plus-focus Fresnel lens 6. Can do.
[0019]
FIG. 9 is a cross-sectional explanatory view showing an embodiment of an illumination device for a fine region according to the second invention. The example of FIG. 9 also shows an illuminating device that illuminates the target component 2 in a soldering appearance inspection device that inspects the state of a soldering part such as an electronic component mounted on the printed circuit board 1, for example. As shown in FIG. 9, the mounting member 3, the light emitter 4, a first Fresnel lens 17a, and a second Fresnel lens 17b are provided.
[0020]
The mounting member 3 and the light emitter 4 are formed in the same manner as in the embodiment shown in FIG. A first Fresnel lens 17 a is provided close to the light emitter 4 in the light irradiation direction of the light emitter 4, that is, on the lower side. The first Fresnel lens 17a guides the irradiation light emitted from the light emitter 4 backward. As shown in FIG. 10, a plurality of prisms having different refraction angles are arranged concentrically on a single plane. 9 is formed as a disk having the same size as the attachment member 3 shown in FIG. 9 as a whole, and a through hole 18 is also formed in a portion corresponding to the through hole 7 of the attachment member 3. Yes. In the example of FIG. 10, the first Fresnel lens 17a functions as a negative focus lens as a whole. By passing through the first Fresnel lens 17a having such a negative focal point, the illumination light emitted from the ring-shaped light-emitting body 4 tends to spread. As a result, the luminance at the peripheral portion is increased with respect to the luminance at the central portion. It can be raised relatively. Note that the first Fresnel lens 17a is provided in the vicinity of the light emitter 4 in FIG. 9 so as to be close to the light emitter 4 with almost no gap therebetween, so that the apparatus can be made compact.
[0021]
A second Fresnel lens 17b is provided close to the downstream side of the optical path of the first Fresnel lens 17a. The second Fresnel lens 17b refracts the light transmitted through the first Fresnel lens 17a in parallel toward the center, and has the same refraction angle on one plane as shown in FIG. A plurality of prisms are arranged concentrically at regular intervals, and formed as a disk having the same size as the mounting member 3 shown in FIG. 9 as a whole, and corresponds to the through hole 7 of the mounting member 3. Similarly, a through-hole 19 is formed in the part to be performed. In FIG. 11, only the right half portion of the second Fresnel lens 17b shown in FIG. 9 is shown.
[0022]
In such a state, the illumination light emitted from the ring-shaped light emitter 4 configured as shown in FIG. 9 is a first Fresnel lens 17a and a second Fresnel lens disposed close to the lower side thereof. By passing through 17b and guiding it backward, it has a flat line image intensity distribution from the central part to the peripheral part as shown in FIG. 12, and a uniform luminance distribution can be formed on the irradiation target surface. Further, as shown in FIG. 11, all the transmitted light of the second Fresnel lens 17b is refracted in parallel toward the central portion, so that it is mounted at different positions on the printed circuit board 1 as shown in FIG. In addition, the light incident on each of the target components 2 and 2 has the same incident angles α and β (α = β), and the optical path lengths l and s leading to the incident angles α and β (l = s), respectively. Thereby, the illumination angle and the light quantity of the illumination light irradiated to the target component 2 shown in FIG. 9 can be made sufficiently uniform regardless of the mounting position.
[0023]
FIG. 14 is a cross-sectional explanatory view showing an embodiment of an illumination device for a fine region according to the third invention. The example of FIG. 14 also shows an illuminating device that illuminates the target component 2 in a soldering appearance inspection device that inspects the state of a soldering part such as an electronic component mounted on the printed circuit board 1, for example. As shown in FIG. 14, the mounting member 3, the light emitter 4, the cylindrical lens 20, and the Fresnel lens 21 are provided.
[0024]
The mounting member 3 and the light emitters 4 are formed in the same manner as in the embodiment shown in FIG. 1, but the light emitters 4 are provided in one row in a ring shape in the example of FIG. A cylindrical lens 20 is provided at a position corresponding to the position of the light emitter 4 in the light irradiation direction of the light emitter 4, that is, on the lower side. The cylindrical lens 20 guides the light emitted from the light emitter 4 to the rear, and is formed by forming a semi-cylindrical rod lens in a ring shape. Therefore, a space corresponding to the through hole 7 of the mounting member 3 is formed at the center of the cylindrical lens 20.
[0025]
A Fresnel lens 21 is provided close to the downstream side of the optical path of the cylindrical lens 20. The Fresnel lens 21 refracts the light transmitted through the cylindrical lens 20 in parallel toward the central portion. As shown in FIG. 11, a plurality of prisms having the same refraction angle are fixed on one plane. Are arranged in concentric circles at intervals of, and are formed in a disk shape having the same size as the attachment member 3 shown in FIG. 14 as a whole, and the portions corresponding to the through holes 7 of the attachment member 3 are also the same. A through hole 22 is formed.
[0026]
In such a state, the illumination light emitted from the ring-shaped light emitter 4 configured as shown in FIG. 14 is transmitted through the cylindrical lens 20 and the Fresnel lens 21 arranged close to the lower side thereof. By guiding backward, it is possible to form a uniform luminance distribution on the irradiation target surface, and all the transmitted light of the Fresnel lens 21 is refracted in parallel toward the central portion, so as shown in FIG. The light incident on each of the target components 2 and 2 mounted on the printed circuit board 1 has the same incident angles α and β (α = β), and the optical path lengths l and s leading to the incident angles α and β, respectively. (l = s). By this. In almost the same manner as the illumination device for a fine area according to the second invention shown in FIG. 9, the effect of uniforming the illumination angle and the amount of illumination light on the target component 2 can be obtained.
[0027]
FIG. 15 is an explanatory view showing a modified example of the combination of the cylindrical lens 20 and the Fresnel lens 21. FIG. 15A shows a combination of the above-described cylindrical lens 20 and a prism 23 having a triangular cross section and formed in a ring shape, and FIG. 15B shows the cylindrical lens 20 and prism 23 of FIG. A lens 24 is shown in which a combination of these is integrally molded at the time of manufacture.
[0028]
FIG. 16 is an explanatory view showing a modification of the cylindrical lens 20. In this modification, the cylindrical lens 20 is not formed in a ring shape as shown in FIG. 14 or FIG. 15A, but a commercially available rod-shaped cylindrical lens 20 ′ is used as it is, and a plurality of the cylindrical lenses 20 ′ are arranged. They are arranged in a circle. In this case, the cost of the cylindrical lens can be reduced.
[0029]
FIG. 14 shows the case where the light emitters 4 are provided in a single ring shape. However, the present invention is not limited to this, and the light emitters 4 are provided in a plurality of ring shapes. A plurality of rings may be provided corresponding to the light emitters 4. FIG. 14 shows the case where the light emitter 4 is a large number of LEDs provided in a single ring shape. However, the present invention is not limited to this, and a single ring-shaped fluorescent tube may be used.
[0030]
【The invention's effect】
Since the present invention is configured as described above, according to the first invention, the illumination light emitted from the ring-shaped illuminant passes through the first lenticular lens and the second lenticular lens and is scattered. The light is further transmitted through a plus-focus Fresnel lens and guided rearward, so that it has a flat line image intensity distribution as shown in FIG. 8 and forms a uniform luminance distribution on the irradiation target surface. Can do. Thereby, the illumination light with which the target component is irradiated can be made uniform. In addition, since a conventional light diffusion smoke plate is not used, uniform illumination light can be obtained while maintaining a high transmittance. Therefore, while maintaining the compactness of the apparatus, the light irradiating the object has high transparency and can be diffused with high efficiency, and the illumination light can be made uniform from the central part to the peripheral part.
[0031]
In addition, according to the second invention, all the light transmitted through the second Fresnel lens is refracted in parallel toward the central portion, so that the individual objects mounted on the printed circuit board as shown in FIG. The light incident on the component has the same incident angles α and β (α = β), and the optical path lengths l and s reaching the same are also equal (l = s). As a result, the illumination light applied to the target component shown in FIG. 9 can be made sufficiently uniform, and the irradiation angle can be kept substantially constant regardless of the illumination light irradiation position.
[0032]
Furthermore, according to the third invention, the effect of uniformizing the illumination angle of the illumination light and the amount of light on the target component can be obtained in almost the same manner as the illumination device for a fine region according to the second invention.
[Brief description of the drawings]
FIG. 1 is a cross-sectional explanatory view showing an embodiment of an illumination device for a fine region according to a first invention.
FIG. 2 is a bottom view showing a mounting state of a light emitter with respect to a mounting member.
FIG. 3 is an explanatory diagram showing a light scattering state by a first lenticular lens.
FIG. 4 is an explanatory diagram showing a light transmission state by a combination of the first lenticular lens and the second lenticular lens.
FIG. 5 is a graph showing the intensity distribution on the object surface of light transmitted through the first lenticular lens and the second lenticular lens combined as described above.
FIG. 6 is a graph showing a line image intensity distribution on the object surface of light transmitted through the first lenticular lens and the second lenticular lens combined as described above.
FIG. 7 is an explanatory diagram showing a structure of a Fresnel lens and a light refraction state in the first invention.
FIG. 8 is a graph showing a line image intensity distribution on an object surface of light transmitted through the Fresnel lens.
FIG. 9 is an explanatory cross-sectional view showing an embodiment of an illumination device for a fine region according to a second invention.
FIG. 10 is an explanatory diagram showing the structure of the first Fresnel lens and the light refraction state in the second invention.
FIG. 11 is an explanatory diagram showing a structure and a light refraction state of a second Fresnel lens in the second invention.
FIG. 12 is a graph showing a line image intensity distribution on an object surface of light transmitted through a combination of the first and second Fresnel lenses.
FIG. 13 is an explanatory diagram showing that an irradiation angle and an optical path length are substantially constant with respect to a target component by the second Fresnel lens.
FIG. 14 is an explanatory cross-sectional view showing an embodiment of an illumination device for a fine region according to a third invention.
FIG. 15 is an explanatory cross-sectional view showing a modification of the combination of the cylindrical lens and the Fresnel lens in the third invention.
FIG. 16 is a plan view showing a modification of the structure of the cylindrical lens in the third invention.
FIG. 17 is a graph showing an intensity distribution or a line image intensity distribution on an object surface when a fine region is illuminated with direct illumination light in a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Printed circuit board 2 ... Target part 3 ... Mounting member 4 ... Light-emitting body 5a ... 1st lenticular lens 5b ... 2nd lenticular lens 6 ... Fresnel lens 7, 11, 14, 16, 18, 19 in 1st invention , 22 through-hole 8 imaging device 9 lens 17a first Fresnel lens 17b in the second invention second Fresnel lens 20, 20 'in the second invention cylindrical lens 21 in the third invention Fresnel lens in the third invention

Claims (5)

A mounting member having a through hole for observing an object in the center, a light emitter provided in a ring shape around the through hole on one side of the mounting member, and a light emitting direction of the light emitter A first lenticular lens which is formed by arranging a large number of cylindrical lenses in parallel on a single plane and also has a through hole in a portion corresponding to the through hole of the mounting member and scatters incident light; The first lenticular lens is provided in close contact with one side and is configured in the same manner as the first lenticular lens, and the arrangement direction of the cylindrical lens intersects the arrangement direction of the cylindrical lens of the first lenticular lens. The second lenticular lens disposed in the vicinity of the optical path downstream of the second lenticular lens and the mounting member Also lighting device fine region characterized in that it comprises a Fresnel lens for directing the light transmitted through the first and second lenticular lens having a through hole to the rear in the region corresponding to the through hole. 2. The microscopic illumination device according to claim 1, wherein the Fresnel lens functions as a positive focus lens as a whole. A mounting member having a through hole for observing an object in the center, a light emitter provided in a ring shape around the through hole on one side of the mounting member, and a light emitting direction of the light emitter A first Fresnel lens that is provided in the vicinity of the light emitter and also has a through hole in a portion corresponding to the through hole of the mounting member, and guides the light emitted from the light emitter backward, and the first Fresnel The lens is provided close to the downstream side of the optical path of the lens and has a through hole in a portion corresponding to the through hole of the mounting member, and refracts the light transmitted through the first Fresnel lens toward the central portion in parallel. An illumination device for a fine region, comprising a second Fresnel lens. 4. The illumination device for a fine region according to claim 3, wherein the first Fresnel lens functions as a negative focus lens as a whole. A mounting member having a through hole for observing an object in the center, a light emitter provided in a ring shape around the through hole on one side of the mounting member, and a light emitting direction of the light emitter A cylindrical lens that is provided in a ring shape corresponding to the position of the light emitter and guides the irradiation light backward, and a portion that is provided close to the downstream side of the optical path of the cylindrical lens and that corresponds to the through hole of the mounting member And a Fresnel lens having a through-hole and refracting the light transmitted through the cylindrical lens in parallel toward the central portion.

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