JP2010086884A - Linear illumination device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a linear illumination device capable of illuminating an irradiated area with an extensive and uniform luminous intensity in a direction perpendicular to a linear direction of a linear light source. <P>SOLUTION: The linear illumination device includes: a linear light source 2; a first lens 3 provided forward of the light source 2; a reflex mirror 4, provided between the linear light source 2 and the first lens 3, for reflecting light emitted from the linear light source 2; and a second lens 5 provided forward of the first lens 3. The reflex mirror 4 has a pair of reflex walls 19 that extend in a linear direction of the linear light source 2 to cover the linear light source 2 from the outside. Direct light emitted from the linear light source 2 and light that is emitted from the linear light source 2 and reflected by the pair of reflex walls 19 are each projected after being converted by the first lens 3 into light beams substantially parallel to each other, and the light beams from the first lens 3 are projected after being converted by the second lens 5 into a converged light beam or light beams substantially parallel to the optical axis, thus a desired irradiated area 23 being irradiated. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a linear illumination device used for illuminating an object to be inspected, for example, in an image processing inspection or the like.

  Conventionally, when inspecting the quality of industrial products such as sheet-like paper, glass substrates, steel plates, etc., such as scratches on the surface, irregularities on the surface, distortion, adhesion of foreign substances, or the state of product end faces on the production line Image processing inspection using imaging by a CCD camera or the like has been performed. In this image processing inspection, a linear illumination device for illuminating an object to be inspected arranged on an irradiation surface is used.

  The linear illumination device 100 generally includes a linear light source 101 and a cylindrical lens 102 that refracts light from the linear light source 101 (see FIG. 8). The linear light source 101 is composed of a plurality of LEDs 103 arranged in a straight line. Light emitted from the linear light source 101 is incident on the cylindrical lens 102, and light emitted from the cylindrical lens 102 irradiates the irradiation surface 104. Another type of linear illumination device includes a linear light source and a reflecting mirror having a cylindrical concave reflecting surface that reflects light emitted from the linear light source (for example, Patent Document 1). reference). The linear light source is composed of a plurality of LEDs arranged in a straight line. Further, in the cross section orthogonal to the linear direction of the linear light source, the concave reflecting surface of the reflecting mirror is constituted by a part of an ellipse having the linear light source as one focal point and the irradiation point as the other focal point. Thereby, the light emitted from the linear light source is reflected by the concave reflecting surface of the reflecting mirror, and the reflected light from the concave reflecting surface is focused on the irradiation surface.

JP 2002-93227 A

  However, the conventional linear illumination device as described above has the following problems. As shown in FIG. 8, the illuminance distribution on the irradiation surface in the direction orthogonal to the linear direction of the linear light source has a sinusoidal distribution with a peak at the center, so that the imaging point by the CCD camera is A slight deviation from the peak of the sine wave of the illuminance distribution causes a problem that the illuminance is remarkably lowered and an optimum imaging result cannot be obtained.

  In addition, a linear light source in which a plurality of LEDs are arranged in a line is a light source that is not linear due to variations in the mounting of LED chips, errors in the arrangement of individual LEDs, etc. It is a light source. For this reason, the peak of illuminance on the irradiated surface is not linear, but has a non-linear shape that is wavy like the light source, and the imaging point is also non-linear.

  An object of the present invention is to provide a linear illumination device capable of illuminating an irradiation surface with a wide range and uniform illuminance in a direction orthogonal to the linear direction of a linear light source.

In the linear illumination device according to claim 1 of the present invention, a linear light source composed of a plurality of LEDs, a cylindrical first lens provided in front of the linear light source, and the linear light source, A reflecting mirror provided between the first lens and reflecting the light emitted from the linear light source; and a cylindrical second lens provided in front of the first lens;
The reflecting mirror includes a pair of reflecting walls extending in the linear direction of the linear light source, covering the linear light source from the outside, and having a specularity extending toward the first lens. Each LED is positioned at or near the front focal point of the first lens,
The direct light emitted from the linear light source and the light from the linear light source reflected by the reflecting wall are each converted into a substantially parallel light flux with respect to each angle of view by the first lens and emitted, The substantially parallel light beam from the first lens is converted into a convergent light beam or a substantially parallel light beam with respect to the optical axis by the second lens and emitted, and irradiates a desired irradiation surface.

In the linear illumination device according to a second aspect of the present invention, the pair of reflection walls are extended and extended outward toward the first lens.
In the linear illumination device according to claim 3 of the present invention, between the opening of the pair of reflecting walls and the first lens or between the first lens and the second lens, A regulating means having a slit for regulating the amount of light incident on the second lens is provided.

  The linear illumination device according to claim 4 of the present invention is characterized in that a separation distance adjusting means for adjusting a separation distance between the first lens and the second lens is provided.

  In the linear illumination device according to claim 5 of the present invention, the first lens and / or the second lens is composed of a linear Fresnel lens.

According to the linear illumination device of the present invention, light having a narrow-angle light distribution including the optical axis out of the light emitted from the linear light source is incident on the first lens and then converted into a substantially parallel light flux with respect to the optical axis. And exits from the first lens. In addition, of the light emitted from the linear light source, light having a wide-angle light distribution toward the outside is reflected by the pair of reflecting walls, and the reflected light is incident on the first lens and then becomes a substantially parallel light flux with respect to the angle of view of the reflected image. Converted. Each substantially parallel light beam emitted from the first lens enters the second lens, and after being converted into a convergent light beam by the second lens, the irradiation surface is irradiated. On this irradiated surface, the direct light emitted from the linear light source and directly incident on the first lens and the reflected light reflected by the pair of reflecting walls and incident on the first lens are superimposed on the irradiated surface. That is, an enlarged image of the opening width of the pair of reflecting walls is formed on the irradiation surface by the second lens. Thereby, the illuminance distribution of the irradiation surface in the direction orthogonal to the linear direction of the linear light source has a substantially uniform irradiation width corresponding to the width of the enlarged image of the opening width of the pair of imaged reflection walls. Illuminance. In other words, the illuminance distribution of the opening width of the pair of reflecting walls is directly imaged as the illuminance distribution of the irradiation width. Therefore, even when an object to be inspected is arranged on the irradiation surface in the image processing inspection and the object to be inspected is illuminated by the linear illumination device, even if the imaging point by the CCD camera is slightly deviated from the linear shape, Therefore, a good imaging result can be obtained. Further, when each substantially parallel light beam emitted from the first lens is converted into a substantially parallel light beam with respect to the optical axis by the second lens, a change in irradiation width on the irradiation surface is reduced regardless of the irradiation distance. be able to.
In addition, according to the linear illumination device of the present invention, the pair of reflecting walls expands and extends outward toward the first lens, so that the wide light distribution emitted from the LED is a pair of reflecting walls. After being reflected, the light is emitted narrower than the opening. Therefore, the size of the first lens and the second lens that cover the light distribution of the light emitted from the pair of reflecting walls can be reduced, and the entire linear illumination device can be reduced in size.

  Further, according to the linear illumination device of the present invention, since the restricting means having the slit for restricting the amount of light incident on the second lens is provided, an enlarged image of the width of the slit by the second lens. Is formed on the irradiation surface, the illuminance on the irradiation surface becomes uniform illuminance having an irradiation width equal to the width of the enlarged image of the slit width. Therefore, the irradiation width can be adjusted by changing the width of the slit. Note that the illuminance and uniformity of the irradiated surface do not change even if the width of the slit is changed.

  Further, according to the linear illumination device of the present invention, the imaging position of the opening or the slit of the pair of reflecting walls, that is, the irradiation distance is adjusted by adjusting the separation distance between the first lens and the second lens. be able to. This is so-called focus adjustment. With this adjustment, since the imaging magnification also changes, the irradiation width of the irradiation surface changes. For example, when the second lens is moved in the direction approaching the first lens, the irradiation distance is increased, the imaging magnification is increased, and the irradiation width on the irradiation surface is increased. Further, when the second lens is moved away from the first lens, the irradiation distance is shortened, the imaging magnification is reduced, and the irradiation width on the irradiation surface is reduced.

  Further, according to the linear illumination device of the present invention, since the first lens and / or the second lens is composed of a Fresnel lens, the thickness of the first lens and / or the second lens can be reduced. The weight can be reduced, and the entire linear illumination device can be reduced in thickness and weight.

  Hereinafter, an embodiment of a linear illumination device according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing a linear illumination device according to an embodiment of the present invention, FIG. 2 is an exploded perspective view showing the configuration of the linear light source of FIG. 1 and its surroundings, and FIG. 1 is an enlarged cross-sectional view showing a configuration of a linear light source 1 and its periphery, FIG. 4 is an explanatory diagram for explaining a light distribution angle of light emitted from the linear light source of FIG. 1, and FIG. FIG. 6 is a schematic explanatory diagram for explaining the illuminance distribution on the irradiation surface by the linear illumination device of FIG. 1, and FIG. 6 explains the illuminance distribution on the irradiation surface by the linear illumination device of FIG. 1 when the restriction plate is omitted. It is a schematic explanatory drawing for this.

  1 to 3, the illustrated linear illumination device 1 includes a linear light source 2, a first lens 3 provided in front of the linear light source 2, a linear light source 2, and a cylindrical first light source 2. A reflecting mirror 4 provided between the first lens 3 and reflecting the light emitted from the linear light source 2; and a cylindrical second lens 5 provided in front of the first lens 3; Arranged in the casing 6. Hereinafter, the configuration of the linear illumination device 1 will be described in detail.

  The casing 6 is mounted on the radiating fins 7, a pair of first side plates 9 attached to both sides of the radiating fins 7 by mounting screws 8, and outside the pair of first side plates 9 slidably in the optical axis direction. A pair of second side plates 10 and a pair of end plates (not shown) attached so as to close both end openings of the pair of first and second side plates 9 and 10 are provided. The casing 6 is formed in a box shape having an upper surface opening by the heat radiating fins 7, the pair of first and second side plates 9 and 10, and the pair of end plates. A screw hole 11 is provided on the outer surface of the first side plate 9, and an adjustment screw 13 is screwed into the screw hole 11. The second side plate 10 is provided with a guide hole 12 extending in the optical axis direction, and an adjusting screw 13 is movably inserted into the guide hole 12. Further, a substantially L-shaped attachment member 14 is attached to each inner surface of the pair of first side plates 9 by attachment screws 15, and one end portion of the attachment member 14 extends inward from the first side plate 9. Yes.

  The linear light source 2 is configured by mounting a plurality of LEDs 16 having a wide light distribution and a high luminous flux type on a long printed circuit board 17 in a line in a straight line. The light from the LED 16 has a light distribution that spreads in a solid angle around the optical axis, and most of the light is emitted within a predetermined range of the solid angle (that is, the effective light distribution angle) around the optical axis. . The printed wiring board 17 is made of aluminum and attached to the heat radiating fins 7.

  The reflecting mirror 4 includes a long plate-like bottom wall 18, a pair of reflecting walls 19 extending from both end portions of the bottom wall 18, and a pair of reflecting end plates 20 respectively extending from both end portions of the bottom wall 18. ing. A reflecting surface is formed on each inner surface of the pair of reflecting walls 19 and the reflecting end plate 20, and a metal thin plate or tape that is subjected to metal vapor deposition, plating, polishing, or mirror surface is provided on the reflecting surface. Mirror surface property is given by sticking. A plurality of through holes 21 are provided in the bottom wall 18, and the LEDs 16 are inserted into the respective through holes 21. The pair of reflecting walls 19 extend in the linear direction of the linear light source 2 (that is, the direction perpendicular to the paper surface in FIG. 1), and the pair of reflective end plates 20 are substantially perpendicular to the linear direction of the linear light source 2. Extending in the direction. Further, the pair of reflecting walls 19 extend outwardly toward the first lens 3 at an angle θ (for example, about 10 °) with respect to the optical axis C (see FIG. 3). A flange 22 extending outward is provided in the opening of the reflecting mirror 4, and the flange 22 is attached to one end of the mounting member 14. A plurality of claws 28 are provided on the outer peripheral portion of the upper surface of the collar portion 22.

The optical axes of the first and second lenses 3 and 5 extend in the linear direction and pass through the center of the cross section orthogonal to the linear direction, and the optical axes of the first and second lenses 3 and 5 are one. I'm doing it.
The first lens 3 is attached so as to cover the opening of the reflecting mirror 4, and the LED 16 of the linear light source 2 is positioned at or near the front focal point F1. On the upper surface of the first lens 3, a restricting plate 25 (which constitutes a restricting means) having a slit 24 is attached, and the first lens 3 and the restricting member are bent by bending the tip portions of the plurality of claws 28 inward. The plate 25 is fixed to the opening of the reflecting mirror 4 by a plurality of claws 28. The slit 24 extends in the linear direction of the linear light source 2, and its width D1 is configured to be smaller than the width D2 of the opening of the pair of reflecting walls 19, and the center in the width direction is positioned on the optical axis. (See FIG. 1 and FIG. 3). The restriction plate 25 may be attached to the other surface of the first lens 3, that is, the opening side of the reflecting mirror 4. Alternatively, it may be mounted away from the first lens 3.

  The second lens 5 is attached to the opening of the casing 6, that is, the opening of the pair of second side plates 10, and the focal point (rear focal point) F <b> 2 is positioned between the second lens 5 and the irradiation surface 23. Yes. In the linear illumination device 1 of the present embodiment, a separation distance adjusting means for adjusting the separation distance H between the first lens 3 and the second lens 5 is provided. The adjusting screw 13 and the guide hole 12 are configured. When the adjustment screw 13 is rotated in the tightening direction, the head portion 26 of the adjustment screw 13 is brought into contact with the outer surface of the second side plate 10, thereby fixing the adjustment screw 13 at that position. On the other hand, when the adjusting screw 13 is rotated in the loosening direction, the head portion 26 of the adjusting screw 13 is separated from the outer surface of the second side plate 10, thereby releasing the fixing of the adjusting screw 13.

  When the second side plate 10 is moved in the direction indicated by the arrow P in FIG. 1 with respect to the first side plate 9, the adjustment screw 13 moves along the guide hole 12, and the second lens 5 moves from the first lens 3. Move in the direction of separation. Further, when the second side plate 10 is moved in the direction indicated by the arrow Q in FIG. 1 with respect to the first side plate 9, the adjustment screw 13 moves along the guide hole 12, and the second lens 5 becomes the first lens. 3 in the direction approaching.

  Next, with reference to FIGS. 3-5, the illumination by the linear illuminating device 1 of this embodiment is demonstrated. When each LED 16 of the linear light source 2 emits light, the light of the narrow distribution light including the optical axis out of the light emitted from the LED 16 is directly incident on the first lens 3 and becomes a substantially parallel light flux by the first lens 3. The light is emitted from the first lens 3. In addition, light of wide light distribution that goes outward from the light emitted from the LED 16 is reflected by the pair of reflection walls 19. This reflected light is the angle of view φ from the virtual image 27 of the LED 16 reflected on the pair of reflecting walls 19 (that is, the angle at which the straight line connecting the center of the first lens 3 and the virtual image 27 is tilted from the optical axis C) (FIG. 3), and enters the first lens 3, and is emitted from the first lens 3 as a substantially parallel light beam having the angle of view φ held by the first lens 3. As described above, since the pair of reflecting walls 19 expands and extends outward toward the first lens 3, the light reflected by the pair of reflecting walls 19 is light that is narrower than the opening. (Ie, the light distribution angle is changed from ω to ω ′) and emitted (see FIG. 4).

  The amount of light of each of the substantially parallel light beams emitted from the first lens 3 is restricted by the slit 24 of the restriction plate 25, but direct light directly incident on the first lens 3 from the LED 16 in the entire width of the slit 24. And the reflected light reflected by the pair of reflecting walls 19 and incident on the first lens 3 overlap each other and have a uniform illuminance distribution. After passing through the slit 24, each substantially parallel light beam enters the second lens 5, and is converted into a convergent light beam by the second lens 5. Each convergent light beam emitted from the second lens 5 is diverged after once forming a light source image of the LED 16 at the rear focal point F <b> 2, and irradiates the irradiation surface 23. The position of the slit 24 and the position of the irradiation surface 23 are in an imaging relationship (conjugate relationship) by the second lens 5, and an enlarged image of the width of the slit 24 is formed on the irradiation surface 23. Therefore, on the irradiation surface 23, like the light beam passing through the slit 24, direct light directly incident on the first lens 3 from the LED 16 and reflected light reflected on the pair of reflecting walls 19 and incident on the first lens 3. Are superimposed again on the irradiation surface 23, and an enlarged image of the width of the slit 24 having a uniform illuminance distribution is formed on the irradiation surface 23. Thereby, the illuminance distribution of the irradiation surface 23 in the direction orthogonal to the linear direction of the linear light source 2 has a substantially uniform illuminance having an irradiation width L corresponding to the width of the enlarged image of the width of the imaged slit 24. (See FIG. 5).

  Therefore, when an object to be inspected (not shown) is arranged on the irradiation surface 23 in the image processing inspection, and this object to be illuminated is illuminated with light emitted from the linear light source 2, an imaging point by a CCD camera (not shown) is used. Even if there is a slight shift, the illuminance does not decrease and a good imaging result can be obtained.

  Further, in the linear illumination device 1 of the present embodiment, the imaging position of the slit 24 by the second lens 5, that is, the irradiation position can be adjusted using the above-described separation distance adjusting means. The irradiation width L of the irradiation surface 23 can be changed as follows. When the second lens 5 is moved in the direction approaching the first lens 3, the irradiation distance (that is, the distance from the second lens 5 to the irradiation surface 23) is increased and the imaging magnification is increased. The irradiation width L is increased. Further, when the second lens 5 is moved away from the first lens 3, the irradiation distance is shortened, the imaging magnification is reduced, and the irradiation width L on the irradiation surface 23 is reduced.

  In the present embodiment, the restricting plate 25 for restricting the amount of light incident on the second lens 5 is provided. However, the restricting plate 25 may be omitted. The illuminance distribution is as shown in FIG. An enlarged image of the width of the opening of the pair of reflecting walls 19 is formed on the irradiation surface 23, and the direct light incident on the first lens 3 from the LED 16 and the pair of reflecting walls 19 are formed over the entire opening. When the reflected light incident on the first lens 3 is superimposed and has a uniform illuminance distribution, and the effective diameter of the second lens 5 is large and no vignetting occurs, the illuminance distribution on the irradiation surface 23 is The illumination intensity is substantially uniform with an irradiation width L ′ corresponding to the width of the enlarged image of the width of the imaged opening. At this time, since the width D2 of the opening of the pair of reflection walls 19 is larger than the width D1 of the slit 24, the width of the enlarged image of the opening is also larger than the width of the enlarged image of the slit 24, and the irradiation width L ′ is It becomes larger than the irradiation width L. At this time, the illuminance when the irradiation width is L and the illuminance when the irradiation width is L ′ are the same. This is because the illuminance is not regulated because the width of the slit 24 regulates the amount of light passing through the slit 24 and ultimately regulates the irradiation width.

  Further, by positioning the slit 24 at or near the front focal point of the second lens 5, the light emitted from the second lens 5 has an angle of view determined by the width of the slit 24 and the focal length of the second lens 5. It can be made into the substantially parallel parallel light beam. Therefore, the change in the irradiation width on the irradiation surface 23 can be reduced regardless of the irradiation distance.

  Next, with reference to FIG. 7, the linear illuminating device of other embodiment is demonstrated. FIG. 7 is an enlarged cross-sectional view showing a configuration of a linear light source and its periphery of a linear illumination device according to another embodiment of the present invention. In the present embodiment, components that are substantially the same as those in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  In the linear illumination device 1A of the present embodiment, the pair of reflection walls 19A extend substantially parallel to the optical axis C toward the first lens 3, and the above-described restriction plate is not provided. Thereby, since the width | variety of the opening part of 19 A of a pair of reflection walls becomes small, the effect similar to the case where a control board is provided is achieved.

  As mentioned above, although one Embodiment of the linear illuminating device according to this invention was described, this invention is not limited to this Embodiment, A various deformation | transformation thru | or correction | amendment are possible without deviating from the scope of the present invention. .

  The linear light source 2 is formed by arranging the LEDs 16 one by one in the linear direction, and is a substantially discontinuous light emitter, and the luminous intensity in the linear direction of the linear light source 2 is uneven. Occurs. For this reason, when it is desired to obtain a uniform luminous intensity in the linear direction of the linear light source 2, a lenticular sheet, a beam-forming sheet, or the like is disposed in the vicinity of the linear light source 2, so Therefore, it is possible to obtain a linear light source 2 having a uniform luminous intensity distribution.

  Further, the first and second lenses 3 and 5 can each be composed of a linear Fresnel lens. A linear Fresnel lens is a flat lens formed by press-molding acrylic resin, for example, and a lens surface is formed on one surface thereof. By configuring in this way, the thickness of the first and second lenses 3 and 5 can be reduced and the weight thereof can be reduced, thereby making the entire linear illumination device 1 thinner and lighter. can do.

It is sectional drawing which shows the linear illuminating device by one Embodiment of this invention. It is a disassembled perspective view which shows the structure of the linear light source of FIG. 1, and its periphery. It is an expanded sectional view which shows the structure of the linear light source of FIG. 1, and its periphery. It is explanatory drawing for demonstrating the light distribution angle of the light emitted from the linear light source of FIG. It is a schematic explanatory drawing for demonstrating the illumination intensity distribution of the irradiation surface by the linear illuminating device of FIG. It is a schematic explanatory drawing for demonstrating the illumination intensity distribution of the irradiation surface by the linear illuminating device of FIG. 1 when a control board is abbreviate | omitted. It is an expanded sectional view which shows the structure of the linear light source of the linear illuminating device by other embodiment of this invention, and its periphery. It is a schematic explanatory drawing for demonstrating the illumination intensity distribution of the irradiation surface by the conventional linear illuminating device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1A, 100 Linear illuminating device 2,101 Linear light source 3 1st lens 4,4A Reflector 5 Second lens 16,103 LED
19, 19A Reflection wall 23 Irradiation surface 24 Slit 25 Restriction plate (regulation means)

Claims (5)

A linear light source composed of a plurality of LEDs; a cylindrical first lens provided in front of the linear light source; and the linear light source provided between the linear light source and the first lens. A reflecting mirror that reflects the light emitted from the first lens, and a cylindrical second lens provided in front of the first lens,
The reflecting mirror includes a pair of reflecting walls extending in the linear direction of the linear light source, covering the linear light source from the outside, and having a specularity extending toward the first lens. Each LED is positioned at or near the front focal point of the first lens,
The direct light emitted from the linear light source and the light from the linear light source reflected by the reflecting wall are each converted into a substantially parallel light flux with respect to each angle of view by the first lens and emitted, The linear illumination device characterized in that the substantially parallel light beam from the first lens is converted into a convergent light beam or a substantially parallel light beam with respect to the optical axis by the second lens and emitted, and irradiates a desired irradiation surface.   2. The linear illumination device according to claim 1, wherein the pair of reflecting walls are extended and extended outward toward the first lens.   Between the opening of the pair of reflecting walls and the first lens, or between the first lens and the second lens, there is a slit for regulating the amount of light incident on the second lens. The linear illumination device according to claim 1, further comprising a regulating unit.   The linear illumination device according to claim 1, further comprising a separation distance adjusting unit configured to adjust a separation distance between the first lens and the second lens.   The linear illumination device according to any one of claims 1 to 4, wherein the first lens and / or the second lens is composed of a linear Fresnel lens.

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