JP2008108618A - Led lighting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an LED lighting system capable of efficiently irradiating light on a required area at any irradiation angle. <P>SOLUTION: The LED lighting system is provided with an outer cylinder 11 with an opening at a center part, an outer shape nearly a frustom of a cone shape, and with an inside equipped with a lens with a curved concave surface firmly fixed, and an inner cylinder 12 with first and second ring-shaped LED substrates firmly fixed inside and engaged with the outer cylinder 11 in free sliding toward an axis direction. The lens may have the curved surface inside as a part of a sphere or an elliptic sphere. By the use of the lens, light can be efficiently irradiated on a required area, so that luminance is more improved than before. Further, an adjustment mechanism is provided at the LED lighting system itself, so that an illumination angle can be easily adjusted with an interval between the lighting device and an object for inspection 10 kept fixed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an LED (light emitting diode) illumination device, and more particularly to an LED illumination device suitable for product inspection and the like.

  Conventionally, when a product image is captured by a camera and a product scratch or printed character is identified, it is known that the contrast between the scratch or the character and the background changes greatly depending on the illumination light irradiation angle. . Therefore, for product inspection and the like, there has been proposed an illuminating device that uses, for example, an LED and can irradiate illumination light at a wide angle.

  The following Patent Document 1 describes an LED lighting device previously filed by the present inventor. FIG. 6 is an explanatory view showing the configuration of product inspection using this LED illumination device. The LED lighting device 81 arranges LED elements inside a half-doughnut-shaped light diffusing resin plate to emit light, so that light along the shape of the light diffusing resin plate is externally reflected by irregular reflection in the light diffusing resin plate. Irradiated uniformly over a wide area. In the product inspection, the LED illumination device 81 illuminates the sample 80, and the camera 83 photographs the surface of the sample 80, scratches, printed characters, and the like.

At this time, the appearance of scratches or printed characters differs depending on the illumination light irradiation angle, and there exists an optimum irradiation angle at which the contrast with the background is maximized, for example. The optimum irradiation angle differs depending on the material of the surface of the sample 80, the finishing method, and the like. Therefore, by changing the distance between the LED lighting device 81 and the sample 80, the light irradiation angle to the sample 80 is changed to find a position where the optimal irradiation angle is obtained, and the LED lighting device 81 is fixed at that position. And when a detection target changes, the position of the LED lighting apparatus 81 is also changed.
JP 2006-073767 A

  In the product inspection as described above, the area that needs to be illuminated is only the central area where the inspection object is placed. However, the above-described conventional LED lighting device irradiates light in all directions below the LED lighting device, and has a problem that illumination efficiency is poor and illuminance is low. In addition, the conventional LED lighting device has a problem that it cannot simultaneously illuminate from different angles. An object of the present invention is to solve the above-described problems and to provide an LED lighting device that can efficiently irradiate light to a necessary region at an arbitrary irradiation angle.

  The LED lighting device according to the present invention includes an opening at a central portion, an external shape is a substantially truncated cone shape, a lens means configured to have a concave curved surface inside, and an opening at a central portion, the lens means The first LED illuminating means for irradiating illumination light from the upper part of the lens, and the second LED illuminating means for irradiating illumination light from the periphery of the lens means with an opening at the center. And

  Further, in the above LED lighting device, the cylindrical outer tube in which the lens unit is fixed inside, and the first and second LED lighting units are fixed in the inside, and the outer tube has a cylindrical shape. And an inner cylinder that is slidably engaged in the axial direction. In the LED lighting device described above, the lens means is also characterized in that an internal concave curved surface is a part of a spherical surface or an elliptical spherical surface.

  Moreover, the above-described LED illumination device is also characterized in that it includes a light diffusing unit provided on the inner surface of the lens unit. In the LED illumination device described above, the lens means is also characterized in that the lower part of the outer surface of the truncated cone shape is wider than the upper part.

  In the LED illumination device described above, the LED illumination means has a large number of LEDs mounted on a ring-shaped LED substrate, and at least some of the LEDs are arranged with the optical axis inclined in the direction of the central axis of the ring. There is also a feature. Further, the above-described LED illumination device is further characterized in that an LED power supply device capable of driving only a specific color LED with an arbitrary current is provided for each LED illumination means.

The LED lighting device of the present invention has the following effects due to the above-described features.
(1) By using a lens, it is possible to efficiently irradiate a necessary region with light. Therefore, when the same LED as the conventional one is used, the illuminance is improved as compared with the conventional one. In addition, the same illuminance as in the conventional case can be obtained with fewer LEDs than in the conventional case, and heat generation is reduced as compared with the conventional case.

(2) Since a plurality of LED substrates as LED illumination means are arranged, illumination light can be irradiated simultaneously from a plurality of angles as required.
(3) Since the adjustment mechanism is provided in the LED illumination device itself, the illumination angle can be easily adjusted while the distance between the illumination device and the inspection object 10 is fixed.

  Embodiments will be described below with reference to the drawings.

  FIG. 1 is a front view showing a configuration of a product inspection apparatus including the LED illumination device of the present invention. The lighting device (outer cylinder) 11 of the present invention is fixed to a support member 15, and the support member 15 is fitted to a support bar 26 fixed to a base 25, and the adjustment knob 16 is rotated. It is configured to move up and down and stop at an arbitrary position.

  The illuminating device (11) has a cylindrical shape having an opening in the upper and lower central portions, and the inner cylinder 12 is slidably engaged with the inside of the outer cylinder 11. A plurality of LED substrates on which a large number of LEDs are mounted are arranged inside the inner cylinder 12. A specially shaped lens (40) is attached to the bottom of the outer cylinder 11. The LED power supply device 14 drives the LED circuit with a constant current independently for each light emission color of the lighting device, for example, by manual setting by an operator. The illumination device 11 illuminates the inspection object 10 from the surroundings at a predetermined irradiation angle based on the driving of the LED power supply device 14.

  The camera 20 to which the lens 21 is attached is fixed to the support member 27 in the same manner as the illumination device 11 and is configured such that the height can be adjusted manually. The camera 20 images the inspection object 10 through the central opening of the illumination device 11 of the present invention, and outputs image data to the monitor device 23, for example. The camera 20 may be a video camera using a CCD image sensor, for example, and may be monochrome, but a color camera is preferred. Further, it may be sensitive to infrared rays or ultraviolet rays.

  FIG. 2 is a cross-sectional view showing the configuration of the LED lighting device of the present invention. The illuminating device 11 has a cylindrical shape having openings 33 and 41 in the upper and lower central portions, and the metal inner tube 12 is slidably engaged with the metal outer tube 11. ing. Inside the inner cylinder 12, two ring-shaped LED substrates 30 and 34 on which a large number of LEDs 31 and 35 are mounted are arranged. The first LED substrate 30 is disposed on the upper portion of the lens 40 (in the apex direction of the lens cone), and is fixed to the inner surface of the ceiling plate of the inner cylinder 12 with the insulating plate 32 interposed therebetween. The inner diameter of the first LED substrate 30 is the same as the diameter of the opening 33. On the first LED board 30, a bullet-type LED 31 having a narrow irradiation angle is mounted in a direction perpendicular to the board.

  The ring-shaped second LED substrate 35 is larger in diameter than the first LED substrate 30 and is formed so that the lens 43 can be inserted into the internal space. The second LED substrate 35 is fixed to the lower inner surface of the inner cylinder 12 around the lens 40. On the second LED substrate 34, a bullet-type LED 31 having a narrow irradiation angle is mounted obliquely toward the central axis of the illumination device. Each LED board 30 and 34 is connected to the LED power supply device 14 by a cable (13) (not shown).

  A lens 40 having a special shape is fixed to the bottom of the outer cylinder 11. The lens 40 is made of a transparent resin or glass, and can be manufactured by cutting a cylindrical block. The shape of the lens 40 is symmetrical with respect to the central axis, and is an approximately truncated cone shape having an opening 41 at the center and a flat surface 42 at the top. The inner surface has a substantially hemispherical shape. The shape on the lower side (the direction opposite to the apex of the cone) from the position indicated by the dotted line AA is different from the upper part, and the bottom of the lower part of the cone of the outer surface 45 is wider than the upper part. The inner surface 46 is not a spherical surface but a conical side surface.

  The inner surfaces 44 and 46 of the lens 40 may be provided with fine irregularities for scattering light as light diffusing means. This processing can be achieved by, for example, sand blasting in which sand is sprayed on the surface.

  FIG. 3 is a cross-sectional view showing the configuration of the adjusting mechanism of the LED lighting device of the present invention. In FIG. 3, the LED substrates 30, 34 and the lens 43 are omitted. In addition, the gaps are exaggerated. In the lighting device, a metal inner cylinder 12 is slidably engaged with a metal outer cylinder 11. Cylindrical protrusions 50 are provided at a plurality of locations inside the outer cylinder 11, and a cylindrical roller 51 is rotatably mounted on the protrusion 50.

  The roller 51 is engaged with an oblique notch 52 provided on the side surface of the inner cylinder 12 and having a width slightly larger than the diameter of the roller 51. Therefore, by rotating the inner cylinder 12 with respect to the outer cylinder 11 about the axis, the roller 51 moves in the notch 52, and the inner cylinder 12 moves in the vertical direction parallel to the axis with respect to the outer cylinder 11. Moving. When the hand is released, the state is maintained by friction between the contact surfaces of the outer cylinder 11 and the inner cylinder 12.

  The position of the inner cylinder 12 shown in FIG. 2 indicates the position when the inner cylinder 12 is lowered to the lowest position. In this position, the optical path of the illumination light when only the LED 35 of the second LED substrate 34 is lit is indicated by a straight line with an arrow. In this case, as shown in FIG. 2, illumination light having a shallow angle with respect to the horizontal plane is irradiated onto the inspection object 10.

  FIG. 5 is a circuit diagram showing a circuit of the LED power supply device 14 of the present invention. The LED power supply device 14 includes three well-known variable constant current power supply circuits 71 to 73 and 74 to 76 corresponding to the LED substrates 30 and 34, respectively. The variable constant current power supply circuits 71 to 73 and 74 to 76 are each adjusted to a desired current value based on manual setting (or an external control signal) by a volume (not shown) or the like.

  For example, red (R), green (G), and blue (B) LEDs are alternately arranged on the substrates 30 and 34, and a plurality of series circuits each including, for example, three LEDs having the same light emitting color are connected in series. Connected in parallel. The number of LEDs connected in series is arbitrary. The lead wires connecting the LED circuits of the respective colors and the variable constant current power supply circuits 71 to 76 are completely independent of each other so that the LED driving current of each color does not affect the LEDs of the other colors. ing.

  FIG. 4 is a cross-sectional view showing the path of illumination light of the LED illumination device of the present invention. 2 shows the position when the inner cylinder 12 is lowered to the lowest position, but FIGS. 4A and 4B show that the inner cylinder 12 is raised to the middle position or the uppermost position with respect to the outer cylinder 11, respectively. The position of the case is shown. In each case, the optical path of the illumination light when both the LEDs 31 and 35 of the two LED boards 30 and 34 are turned on is indicated by a straight line with an arrow.

  As shown in the drawing, in (a), the illumination light is irradiated to the inspection object 10 from an oblique direction, and in (b), the illumination light is irradiated from a direction perpendicular to the inspection object 10. Therefore, it is possible to easily adjust the illumination angle while fixing the distance between the illumination device and the inspection object 10.

  As described above, the LED illumination device of the present invention can illuminate any color at any illumination angle by adjusting the relative position of the outer cylinder 11 and the inner cylinder 12 and the LED power supply device 14. For example, the illumination can be adjusted so that the contrast between the scratch or print and the background is maximized.

  FIG. 7 is a cross-sectional view showing the configuration of another embodiment of the lens of the LED lighting device of the present invention. In FIG. 7A, the outer surface 91 of the lens 90 has a simple truncated cone shape, and the inner surface is a combination of a hemispherical surface 93 and a conical side surface 94 having the same shape as the outer surface. In FIG. 7B, the outer surface 91 of the lens 90 has the same shape as that of the first embodiment, and the inner surface is an hemispherical surface combined with an elliptical sphere (solid whose vertical section is elliptical) surface 95 and a conical side surface. It is intended.

  FIG. 7C shows a shape in which a connecting portion between the conical side surface of the outer surface of the lens 90 and the upper plane is formed by a smooth curved surface. A connecting portion of the outer surface or the inner surface in the vicinity of the dotted line AA may be configured with a smooth curved surface. FIG. 7D shows a shape in which the portion below the dotted line AA on the outer surface of the lens 90 is formed by a smooth convex curved surface.

Although the embodiments have been described above, the following modifications may be considered in the present invention. In the embodiment, the upper surface 42 of the lens 40 is a flat surface, but the upper surface may have a conical side surface shape 99 as shown in FIG. If it does in this way, the condensing effect from the upper part will increase more.
In the embodiment, an example in which two LED boards are provided has been disclosed. However, for example, a third LED board having the same configuration as the second LED board may be provided in the central portion of the side surface of the inner cylinder 12.

In the embodiment, the example in which the adjustment of the lighting device is performed manually is disclosed. However, even if the movement of the support member 15 and the outer cylinder 11 with respect to the support rod 26 and the movement of the inner cylinder 12 with respect to the outer cylinder 11 are driven by a stepping motor. Good. Further, the outer cylinder 11 may be moved while the inner cylinder 12 is fixed to the support member 15.
In the embodiments, the lighting device having a circular horizontal cross section is disclosed, but the horizontal cross section may be a polygon having an arbitrary number of corners of a square or more.

It is a front view which shows the structure of the product inspection apparatus containing the LED lighting apparatus of this invention. It is sectional drawing which shows the structure of the LED lighting apparatus of this invention. It is sectional drawing which shows the structure of the adjustment mechanism of the LED lighting apparatus of this invention. It is sectional drawing which shows the path | route of the illumination light of the LED lighting apparatus of this invention. It is a circuit diagram which shows the circuit of the LED power supply device 14 of this invention. It is explanatory drawing which shows the structure of the conventional LED lighting apparatus. It is sectional drawing which shows the other Example of the lens of the LED lighting apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Inspection object 11 ... LED lighting device outer cylinder 12 ... LED lighting device inner tube 13, 22 ... Cable 14 ... LED power supply device 15, 27 ... Support member 16, 28 ... Adjustment knob 20 ... Camera 21 ... Lens 23 ... Monitor device 25 ... Base 26 ... Support bar

Claims (7)

Lens means comprising an opening in the center, the outer shape is substantially frustoconical, and the inside is configured as a concave curved surface,
A first LED illuminating means comprising an opening in the center and irradiating illumination light from an upper part of the lens means;
An LED illuminating device comprising: a second LED illuminating unit provided with an opening at a central portion and irradiating illumination light from around the lens unit. A cylindrical outer cylinder to which the lens means is fixed; and
The first and second LED illuminating means are fixed inside, and have a cylindrical shape and an inner cylinder that is slidably engaged with the outer cylinder in the axial direction. The LED lighting device according to 1.   2. The LED illumination device according to claim 1, wherein the lens means has an inner concave curved surface that is a spherical surface or a part of an elliptic spherical surface.   The LED illumination device according to claim 1, further comprising a light diffusing unit provided on an inner surface of the lens unit.   The LED illumination device according to claim 1, wherein the lens means has a lower part of the outer surface of the truncated cone shape wider than an upper part.   The LED illumination means includes a plurality of LEDs mounted on a ring-shaped LED substrate, and at least some of the LEDs are arranged such that an optical axis is inclined in a central axis direction of the ring. The LED lighting device according to 1.   The LED illumination device according to claim 1, further comprising an LED power supply device capable of driving only a specific color LED with an arbitrary current for each LED illumination means.

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