JP2008286716A - Led illuminator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brighter LED illuminator capable of covering a wide range of illumination angle of light. <P>SOLUTION: The LED illuminator formed into a doughnut shape as a whole is provided with: a case 10 having one plane perpendicular to the center axis and an inner plane being continuous with the one plane and opened at the bottom; a ringlike printed wiring board 13 which is disposed inside the case and has a plurality of LED elements for emitting light in the direction of the center axis of the case; and an approximately doughnut-shaped lens 11 which is disposed between the plurality of LED elements and the center axis of the case and configured to engage with the open plane of the case so as to be movable parallel to the center axis of the case, and keeps cross section on the LED element side in the form of a circular arc. The wide range of illumination angle of the light is covered by moving the lens, and the condensing function of the lens makes the LED illuminator bright. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an LED (light emitting diode) illumination device, and 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. . The optimum irradiation angle at which the contrast between the scratch or character and the background is maximized differs depending on the material of the surface of the product and the finishing method. Therefore, for product inspection and the like, there has been proposed an illumination device that can illuminate illumination light at a wide angle using, for example, an LED.

The following Patent Document 1 describes an LED lighting device previously filed by the present inventor. The LED illuminating device includes a plurality of LEDs arranged such that an optical axis is inclined in the direction of the central axis of the illuminating device, and an axis that is disposed on the front surface of the LED and extends from the center of the LED to the center of the lens. And an inclined lens. Since it is possible to efficiently irradiate the necessary area with light, the illuminance is higher than in the past.
JP, 2007-10380, A FIG. 6 is explanatory drawing which shows the composition of the product inspection which uses this LED lighting device. In product inspection, a sample 53 is illuminated by an LED illumination device 51 (52) supported by a support device (not shown) so that the height can be adjusted, and the CCD camera 50 removes scratches on the surface of the sample 53, printed characters, and the like. Take a picture. Here, by changing the distance between the LED lighting device and the sample 53, the irradiation angle of the light to the sample 53 is changed to find a position where the optimal irradiation angle is obtained, and the LED lighting device is fixed at that position.

The above-described conventional LED illumination device has a problem that the range of the bright light irradiation angle is narrow and the entire image becomes dark as the distance from the sample increases. Therefore, when the detection target is changed, it is necessary to replace the LED lighting device suitable for the inspection target or change the position of the LED lighting device, which is troublesome.
An object of the present invention is to solve the above-described problems and to provide a brighter LED illumination device that covers a wide range of light irradiation angles.

  The LED lighting device of the present invention is generally donut-shaped with an opening at the center, one surface perpendicular to the central axis, and the lower part of the inner cylinder that forms the opening that follows the one surface Disc-shaped printed wiring board having a case with an open surface, a plurality of LED elements that are mounted inside the case and that irradiate light in the central axis direction of the case, and that has an opening at the center And can be moved parallel to the central axis of the case by fitting to the open surface of the case, and disposed between the plurality of LED elements and the central axis of the case, and the surface on the side of the plurality of LED elements Is characterized by comprising a substantially donut-shaped lens having a circular cross section.

  Moreover, the above-described LED illumination device is characterized in that the surface of the lens on the central axis side of the case has a conical side surface shape.

The LED lighting device of the present invention has the following effects due to the above-described features.
(1) By making the lens movable, it is possible to cover a wider range of light irradiation angles than the conventional illumination device. Therefore, it is not necessary to replace the illumination device for each inspection, and various inspections can be performed with one LED illumination device.
(2) By making the lens movable, it is not necessary to adjust the vertical position of the LED illuminating device itself, or the adjustment range may be smaller than in the past.
(3) By making the lens movable, it is possible to illuminate the LED illuminating device itself by placing it closer to the sample than before, and illumination that is brighter than before can be achieved.
(4) By using a lens having a special shape, illumination that is brighter and more uniform than before can be achieved.

  Embodiments will be described below with reference to the drawings.

  FIG. 1 is a plan view and a cross-sectional view showing a configuration of an embodiment of an LED lighting device of the present invention. The LED lighting device of the present invention is roughly composed of a case 10, a printed wiring board 13 having a plurality of LEDs 12, and a movable lens 11.

  The case 10 is generally doughnut-shaped with an opening 14 at the center, and has one surface perpendicular to the central axis 16 of the case (the lower surface in the cross-sectional view of FIG. 1) and the opening continuing to this one surface. The lower surface of the inner cylindrical part 17 forming 14 is opened. Accordingly, the case 10 has a shape in which the upper disk portion, the outer cylindrical portion 18 and the inner cylindrical portion 17 are combined, and the cross section of the case has a shape in which a substantially J-shape is turned upside down.

  The case 10 is integrally formed of a metal such as aluminum in order to obtain a heat dissipation effect. The case 10 is fixed to a supporting device (not shown) with a screw by, for example, providing a threaded hole in the upper disk part.

The printed wiring board 13 on which the circuit for the LED element 12 is formed is fixed to the inside of the case 10 with, for example, a screw or an adhesive (not shown) across an insulating sheet.

  FIG. 4 is a plan view showing the configuration of the printed wiring board 13. The printed wiring board 13 has a disk (ring) shape with an opening in the center, and on the board, as shown in FIG. 4, a plurality of LED elements 12 are in the direction of the central axis 16 of the case, 1 is mounted so that light is emitted in a direction parallel to the substrate 13 in the horizontal direction of the cross-sectional view of FIG. The printed wiring board 13 is connected to an LED driving device 40 described later by a lead wire 22.

  The LED elements 12 are mounted at different heights from the substrate 13 in order to reduce uneven illumination and to increase the LED arrangement density. The LED element 12 may be, for example, a white LED element having a bullet-type lens. Such LED elements are commercially available.

  The lens 11 is made of, for example, a transparent resin, and has a substantially donut shape as a whole as in the case. The lens 11 is disposed between the plurality of LED elements 12 and the central axis 16 of the case 10, and the surface of the lens 11 on the LED element side has an arc shape with a substantially semicircular cross section.

  The center 15 of the circular arc of the cross section of the lens is substantially equal to the inner cylinder 17 at a distance from the central axis 16 of the case 10 and is located near the center of the optical axis of the LED element 12 when the lens 11 is moved upward. To do. The diameter of the circular arc in the cross section of the lens 11 is about 1/3 of the central opening 14. Further, the surface of the case of the lens 11 on the central axis side has a conical side surface shape with a smaller diameter toward the top.

  A lens internal cylindrical portion 19 is integrally formed at an end portion of the lens 11 on the case 10 side, and a lens disk portion 20 perpendicular to the central axis 16 is formed at an end portion of the lens 11 opposite to the case 10. Are integrally formed, and a lens external cylindrical portion 21 is integrally formed at the edge of the lens disk portion 20.

  The lens inner cylindrical portion 19 is slidably fitted to the side opposite to the central axis 16 of the inner cylindrical portion 17 of the case, and the lens outer cylindrical portion 21 is slidable on the inner surface of the outer cylindrical portion 18 of the case. It is mated. Accordingly, the lens 11 can move by a predetermined length in parallel with the central axis 16 of the case 10.

  FIG. 2 is a cross-sectional view showing a state in which the lens is moved in the LED lighting device of the present invention. The lens locking screw 26 passes through a long hole 27 provided in the outer cylindrical portion 18 of the case 10 in the direction of the central axis 16 and fits into a screw hole provided in the lens outer cylindrical portion 21. ing. When the lens 11 is moved, first, the screw 26 is loosened and the position of the lens 11 is adjusted. After the adjustment is completed, the screw 26 is tightened again to fix the lens 11 to the case 10.

  FIG. 2A shows an arrangement when the lens 11 is moved in the direction of the case 10. When the LED element 12 and the lens 11 are positioned as shown in FIG. 2A, the light emitted from the LED is condensed by the lens 11 in a direction close to the horizontal in FIG. Illuminate.

  FIG. 2B shows an arrangement when the lens 11 is moved in the direction opposite to the case 10. When the LED element 12 and the lens 11 are positioned as shown in FIG. 2B, the light emitted from the LED is condensed obliquely downward in FIG. . In either case, the light emitted from the LED element 12 is collected by the lens 11, so that the illuminance is improved.

  FIG. 5 is a circuit diagram showing circuits of the LED lighting device and the LED driving device of the present invention. In the printed wiring board 13, a series circuit in which, for example, three white LED elements are connected in series is connected in parallel. The number of LEDs connected in series is arbitrary. The LED driving device 40 includes a variable constant current power supply circuit 41 and a control circuit 44 that controls the variable constant current power supply circuit 41 to a desired current value based on a manual setting by an external control signal or volume.

FIG. 3 is a cross-sectional view illustrating a configuration of a second embodiment of the LED lighting device according to the present invention. In the first embodiment, an example in which the LED element 12 is mounted at a right angle to the central axis 16 toward the central axis 16 has been disclosed. However, in this configuration, the illuminance in the horizontal direction is sufficiently bright, but the illumination angle is There is a problem that it gets darker as it gets closer to the vertical.
Therefore, in Example 2, the plurality of LED elements 30 are mounted so as to emit light in the direction of the central axis 16 of the case and obliquely downward in the cross-sectional view of FIG. By adopting such a configuration, the illuminance can be increased even when the illumination angle is nearly vertical.

  Although the embodiments have been disclosed above, the present invention can be modified as follows. In the embodiment, an example in which the lens is formed of a transparent material has been disclosed. However, the lens may be provided with a light diffusing means. As the light diffusing means, for example, sandblasting or the like is applied to one or both of the front surface and the back surface of the lens so that the light is irregularly reflected on the front surface. Or you may affix a light-diffusion sheet on either the surface of a lens, a back surface, or both. The material of the lens 11 may be formed of a resin that diffuses light such as milky white. Furthermore, a light diffusion plate made of, for example, a resin that diffuses light may be disposed in the space between the LED element 12 and the lens 11. By providing the light diffusion means, the illuminance unevenness is reduced.

  In the embodiment, the surface on the central axis side of the case of the lens 11 is disclosed as a conical side surface shape having a smaller diameter toward the upper part. However, depending on the irradiation angle range, the central axis side of the case of the lens 11 is disclosed. The surface may be cylindrical, or may be a conical side surface having a larger diameter at the top.

  The LED lighting device of the present invention can be applied to lighting at the time of product inspection or the like.

It is the top view and sectional drawing which show the structure of the Example of the LED lighting apparatus of this invention. It is sectional drawing which shows the state which moved the lens in the LED lighting apparatus of this invention. It is sectional drawing which shows the structure of Example 2 of the LED lighting apparatus of this invention. It is a top view which shows the structure of a printed wiring board. It is a circuit diagram which shows the circuit of the LED lighting apparatus of this invention, and an LED drive device. It is explanatory drawing which shows the structure of the product test | inspection which uses this LED lighting apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Case 11 ... Lens 12 ... LED element 13 ... Printed wiring board 14 ... Opening 16 ... Center axis 22 of case ... Lead wire 25 ... Sample 26 ... Screw for locking

Claims (2)

A case where the whole is substantially donut-shaped with an opening at the center, and one surface perpendicular to the central axis and the lower surface of the inner cylinder that forms the opening that continues to the one surface are open When,
A disk-shaped printed wiring board mounted inside the case, mounted with a plurality of LED elements that irradiate light in the central axis direction of the case, and having an opening at the center,
The open surface of the case is fitted and movable in parallel with the central axis of the case, and is disposed between the plurality of LED elements and the central axis of the case, and the surface on the side of the plurality of LED elements is a cross section. And a substantially donut-shaped lens having a circular arc shape.   The LED lighting device according to claim 1, wherein a surface of the lens on the central axis side of the case has a conical side surface shape.

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