JP4836231B2 - LED lighting device - Google Patents

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 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. FIG. 6 is an explanatory view showing the configuration of product inspection using this LED illumination device. The LED lighting device 81 arranges the LED elements inside the half-doughnut-shaped light diffusion resin plate and emits light, so that light along the shape of the light diffusion resin plate is externally reflected by irregular reflection in the light diffusion 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, printed characters, and the like differs depending on the illumination angle of the illumination light. For example, there is an optimum illumination angle that maximizes the contrast with the background. 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.
Registered Utility Model Publication No. 3085058

  In the product inspection as described above, the area that needs to be illuminated is only the area in the vicinity where the inner sample 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, in order to increase the illuminance, a large number of LEDs are required, and heat generation is increased, which makes it difficult to reduce the size. An object of the present invention is to solve the above-described problems and to provide an LED illumination device that can efficiently irradiate light to a necessary area with a small number of LEDs.

  The LED lighting device of the present invention is arranged around a central opening portion, and LED light emitting means comprising a plurality of LEDs arranged with the optical axis inclined in the direction of the central axis of the lighting device, and the front surface of the LED light emitting means And a lens unit that has an axis extending from the center of the LED light emitting unit to the center of the lens in a cross section passing through the central axis of the lighting device is inclined toward the central axis.

  Further, the above-described LED illumination device is characterized in that one or both surfaces of the lens means, and a light diffusion means provided between the LED light emitting means and the lens means are provided. Further, in the LED lighting device described above, the LED light emitting means is a plurality of surface-mounted LEDs mounted on a printed wiring board having a shape in which a conical side surface is cut at a plane perpendicular to the axis at different positions. There is also a feature.

  The LED lighting device according to claim 1, wherein the lens means has a circular cross section. Further, in the LED lighting device described above, the LED light emitting means includes LEDs arranged in a plurality of concentric circular rows, and further includes a lighting row control means for selectively lighting only LEDs in a specific row. There are features.

  Further, the LED lighting device described above is characterized in that it includes lens position adjusting means for adjusting the position of the lens means with respect to the base. In addition, the above LED lighting device is characterized in that it includes LED position adjusting means for adjusting the position of the LED light emitting means with respect to the base.

  Another LED illumination device of the present invention is characterized in that a linear illumination unit incorporating a plurality of LEDs and lenses is rotatably held. In addition, the above-described LED illumination device is characterized in that a plurality of illumination units are arranged in a ring shape and provided with connecting and rotating means for rotating all the illumination units in conjunction with each other.

  The LED illumination device of the present invention can efficiently irradiate a necessary region with light due to the above-described features, and therefore, when the same LED as the conventional LED is used, there is an effect that the illuminance is higher than the conventional one. Further, even with fewer LEDs than the conventional one, the same illuminance as before can be obtained, and there is an effect that heat generation is reduced as compared with the conventional one.

  If the LED lighting device is equipped with the adjusting means of the present invention, it is possible to adjust the main irradiation angle and the degree of light collection at the time of shipment or at the site of product inspection, and adjust so that the illuminance is maximized at a specific irradiation angle. There is an effect that can be done.

  Embodiments will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a configuration of Examples 1 to 3 of the LED lighting device of the present invention. Moreover, FIG. 2 is the front view and side view which show the structure of the LED lighting apparatus of this invention. As shown in FIG. 2, the LED lighting device 10 of the present invention has a circular or square shape having an opening 25 at the center. The shape may be a regular polygon having an arbitrary number of corners.

  The LED illumination device 10 includes a base 11, a cover 12 that also serves as a lens 13, and a printed wiring board 16 on which a plurality of LEDs 15 are mounted concentrically. The base 11 is a base for configuring the LED lighting device 10 and is fixed to a support device (not shown) with a screw by providing, for example, a threaded hole. The base 11 is made of a metal plate such as aluminum in order to give a heat dissipation effect.

  The cover 12 is formed by cutting a block made of a transparent resin material into a semi-doughnut shape in which the entire shape is cut by a plane perpendicular to the central axis or injection molding. A part of the cover 12 also serves as the lens 13. The optical axis 18 of the lens 13 in a cross section passing through the central axis 17 of the LED lighting device 10 is inclined with respect to the central axis 17. The cover 12 is fixed to the base 11 with an adhesive or the like.

  As the shape of the lens 13, a shape of a single convex lens having a straight cross section inside the cover 12 is disclosed in FIG. 1, but the shape of the lens is a biconvex lens, a lens having a circular cross section, a Fresnel lens, or the like. Any known lens shape having can be used.

  The ring-shaped printed wiring board 16 is fixed to the base 11 with screws or an adhesive (not shown) with an insulating sheet interposed therebetween, for example. A plurality of LEDs 15 are mounted on the printed circuit board 16 in, for example, three rows of concentric circles. The individual LEDs 15 are arranged such that their optical axes are inclined in the direction of the central axis of the lighting device, and the optical axis of the LEDs 15 and the optical axis 18 of the lens 13 are parallel to each other.

  The distance between the LED 12 and the lens 13 and the direction of the optical axis may be determined by experiments so that the illuminance unevenness is within the allowable range within the required irradiation region and the illuminance is as high as possible.

  FIG. 5 is a circuit diagram showing circuits of the LED lighting device 10 and the LED driving device 70 of the present invention. In the illuminating device 10, the LED 15 includes, for example, a plurality of series circuits in which red (R), green (G), and blue (B) LEDs are alternately arranged on the substrate 16 and, for example, three LEDs 15 having the same emission color are connected in series. Connected in parallel. The number of LEDs connected in series is arbitrary.

  The LED driving device 70 includes three variable constant current power supply circuits 71, 72, and 73 and three variable constant current power supply circuits 71, 72, and 73 based on manual setting by an external control signal or volume. The control circuit 74 controls the current value to a desired value.

  It should be noted that the LED drive current of each color of the lighting device 10 and the three variable constant current power supply circuits 40, 41, 42 in the LED drive device 21 so that the LED drive current of each color does not affect the LEDs of other colors. The lead wires that connect them are completely independent of each other. Since any color illumination is possible with such a configuration, for example, it is possible to adjust to an optimum color that maximizes the contrast between a scratch or print and the background.

  In the configuration of the first embodiment, in a cross section passing through the central axis 17 of the LED lighting device 10, the axis 18 extending from the center of the LED 15 to the center of the lens 13 is inclined toward the central axis 17, thereby being condensed by the lens 13. Since the direction of the optical axis 18 with the strongest light is directed toward the central axis 17 of the LED lighting apparatus 10 on which the sample is placed, the illuminance near the sample is improved as compared with the conventional case when the same LED is used.

  FIG.1 (b) is sectional drawing which shows the structure of Example 2 of the LED lighting apparatus of this invention. In the second embodiment, a light diffusing unit is added to the configuration of the first embodiment. As the light diffusing means, for example, sandblasting or the like is performed on one or both of the front surface 14 and the inner surface (back surface) of the lens 13 so that light is irregularly reflected on the front surface. Or you may affix the light-diffusion sheet 14 on either the surface of the lens 13, an inner surface (back surface), or both.

  Further, the material of the lens 13 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 15 and the lens 13. By providing the light diffusing means, uneven illuminance and uneven color due to the location and the height of the illumination device 10 are reduced. The configuration of the second embodiment can be implemented in combination with the configurations of the third and later embodiments described later.

  FIG.1 (c) is sectional drawing which shows the structure of Example 3 of the LED lighting apparatus of this invention. Example 3 is an example in which a curved surface board is used as the printed wiring board 19 in the configuration of Example 1, and the surface-mounted LED 20 can be mounted. The printed wiring board 19 has a curved shape obtained by cutting a conical side surface at a different position along a plane perpendicular to the axis, and the surface-mounted LED 20 is mounted thereon. Such a curved printed wiring board is available. According to the third embodiment, the LED 20 can be easily positioned, and the LED lighting device can be easily manufactured. The configuration of the third embodiment can be implemented in combination with the configurations of the fourth to seventh embodiments described later.

  Fig.3 (a) is sectional drawing which shows the structure of Example 4 of the LED lighting apparatus of this invention. The fourth embodiment is an example in which the lens 31 having a circular cross section is employed in the configuration of the first embodiment. The lens 31 has a circular donut shape in cross section, and such a lens is easily available. By adopting such a lens, the light collection rate is improved and the illuminance is increased. The lens shape may be a biconvex lens.

  In the configuration of the fourth embodiment, as in the first embodiment, the optical axis extending from the center of the LED 15 to the center of the lens 31 in the cross section passing through the central axis of the LED lighting device 10 is inclined toward the central axis, thereby the lens 31. Since the direction of the strongest optical axis of the light collected by the light is directed toward the central axis of the LED illumination device 10 on which the sample is placed, the illuminance in the vicinity of the sample is improved as compared with the conventional case when the same LED is used. The configuration of the fourth embodiment can be implemented in combination with the configurations of the fifth to seventh embodiments described later.

  FIG.3 (b) is sectional drawing which shows the structure of Example 5 of the LED lighting apparatus of this invention. The fifth embodiment is an example in which, in the configuration of the fourth embodiment, a row to be driven is selected from among a plurality of rows of LEDs 32. A plurality of LEDs 32 are arranged in, for example, five rows of concentric circles on the printed wiring board. The individual LEDs 32 are arranged so that the optical axis faces the center of the lens 31. Each of the five columns of LEDs 32 includes an independent circuit, and is configured to be turned on / off independently.

  In Example 5, for example, when it is desired to obtain an irradiation angle close to vertical, only the inner three rows of LEDs 32 are turned on. If the irradiation angle is desired to be about 45 degrees, only the outer three rows of LEDs are turned on. When it is desired to set the irradiation angle to about 60 degrees, only the middle three rows of LEDs are turned on. Thus, by selecting the row of the LEDs 32 to be turned on, it is possible to change the most intense irradiation angle of light.

  In this embodiment, if the illuminance is sufficient, only one column or two adjacent columns may be turned on. Further, if the heat generation is allowable, the adjacent four or five rows may be turned on. The configuration of the fifth embodiment can be implemented in combination with the configurations of the sixth and seventh embodiments described later.

  FIG.3 (c) is sectional drawing which shows the structure of Example 6 of the LED lighting apparatus of this invention. The sixth embodiment is an example in which the position of the lens 13 or 31 can be adjusted in the vertical direction in the configurations of the first to fifth embodiments. The base 35 is provided with two inner and outer cylindrical ribs, and the outer surface of the outer rib 36 is threaded. Further, an inner surface of the base 37 of the cover 37 facing the screw thread is also threaded to fit the screw thread.

  Accordingly, by fixing the base 11 and rotating the entire cover 37, the vertical distance between the lens and the base 11 changes, and the LED 15 mounted on the substrate fixed to the base 11 is changed. The distance also changes. In addition, since the vertical position of the center of LED15 and the center of lens 31 has shifted | deviated in the cross section which passes along the central axis of LED lighting apparatus 10, if the distance of a lens and LED15 is changed, the irradiation angle of light will also change.

  In Example 6, it is possible to adjust the illuminance to be the highest at a desired irradiation angle in the field, and there is an effect that the irradiation efficiency is further improved. In the sixth embodiment, since the cover 37 can be attached and detached, the lens can be exchanged in the field by preparing a plurality of types of covers with lenses. The thread may be provided on the inner rib, or the rib 36 may be on the outer side of the cover 37.

  FIG.3 (d) is sectional drawing which shows the structure of Example 7 of the LED lighting apparatus of this invention. The seventh embodiment is an example in which the position of the printed wiring board 44 on which the LED is mounted can be adjusted in the vertical direction in the configurations of the first to sixth embodiments. A screw hole is provided at a position obtained by dividing the circumference of the base 40 into three equal parts, and a screw 41 is inserted. In FIG. 3D, the screws appear on both sides, but when the screws are provided at three positions, the screws do not appear on both sides of the cross section.

  The lower part of the screw hole is smaller in diameter than the head of the screw 41. The screw 41 passes through the screw hole, the coil spring 43 and the printed wiring board 44 and is fitted to the nut 42. The nut 42 is fixed to the printed wiring board 44 or engaged with the board 44 so as not to rotate.

Therefore, the position of the printed wiring board 44 on which the LEDs are mounted can be adjusted in the vertical direction by rotating the three screws 41 by the same rotation angle by the driver. If the number of screws 41 is two, the substrate is not sufficiently fixed, and if the number is four or more, the substrate may be twisted.
In the seventh embodiment, it is possible to adjust the illuminance to be the highest at a desired irradiation angle in the field, and there is an effect of further improving the irradiation efficiency.

  FIG. 4: is the front view and sectional drawing which show the structure of Example 8 of the LED lighting apparatus of this invention. In the eighth embodiment, a linear illumination unit incorporating a position-adjustable LED and lens is rotatably held. And the some illumination unit is arrange | positioned cyclically | annularly and it has the connection means which all the illumination units rotate in response.

  The eighth embodiment shown in FIG. 4 uses four lighting units 50. A square base 53 having an opening in the center includes box-shaped members that rotatably support the lighting unit 50 at four corners, and four lighting units 50 are rotatably mounted on the box-shaped members.

  Bevel gears 52 having an inclination angle of 45 degrees are formed on the circumferential portions of the end portions of the respective lighting units 50, and adjacent bevel gears 52 are engaged with each other. Accordingly, when one illumination unit 50 is rotated, the other illumination units 50 are also rotated so that the angle formed by the optical axis of the illumination unit 50 and the central axis of the illumination device 10 is the same angle.

  As shown in FIGS. 4B to 4D, the lighting unit 50 has a printed wiring board 58 with a large number of LEDs 61 mounted in a cylindrical case so that the position thereof can be adjusted. A lens-like lens 61 is formed on the front surface of the LED 61 integrally with the case. Both ends of the printed wiring board 58 are held by, for example, the same screw 55, nut 56, and spring 57 as the structure of the seventh embodiment shown in FIG. 3D, and the two screws 55 are rotated by the same rotation angle. By doing so, the distance between the LED 61 and the lens 60 can be adjusted.

  In this embodiment, since the distance between the LED 61 and the lens 60 and the direction (optical axis direction) of the illumination unit 50 with respect to the base 53 can be adjusted, it is optimal according to the required irradiation angle, irradiation area, illuminance, etc. Adjustments can be made to the state.

  In the embodiment, an example in which four illumination units 50 are used has been disclosed. However, it is also possible to create an illumination device by using five or more arbitrary units. Further, the printed wiring board 58 may be fixed to the case by omitting the screw 55 that is a means for adjusting the distance between the LED 61 and the lens 60. Further, the bevel gear 52 may be omitted and each lighting unit may be configured to rotate independently.

It is sectional drawing which shows the structure of Examples 1-3 of the LED lighting apparatus of this invention. It is the front view and side view which show the structure of the LED lighting apparatus of this invention. It is sectional drawing which shows the structure of Examples 4-7 of the LED lighting apparatus of this invention. It is the front view and sectional drawing which show the structure of Example 8 of the LED lighting apparatus of this invention. It is a circuit diagram which shows the circuit of LED lighting apparatus 10 and LED drive device 70 of this invention. It is explanatory drawing which shows the structure of the product inspection which uses LED lighting apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... LED illumination apparatus 11 ... Base 12 ... Cover 13 ... Lens 14 ... Light-diffusion sheet 15 ... LED
16 ... Printed circuit board

Claims (4)

A circular or square base with an opening in the center;
It is circular or square with an opening in the center of the same shape as the base, and is mounted on a printed wiring board fixed to the base, and the optical axis is inclined to the central axis direction of the lighting device A plurality of LEDs,
Approximately in the center of the same shape it is circular or square with an opening, and are disposed in front of the LED, and extends in a cross-section through the central axis of the illumination device to the center of the lens from the center of the LED and the base a cover having a convex lens axis is inclined to the central axis side,
An LED illumination device comprising: lens position adjusting means for adjusting a distance between the lens and the LED. LED lighting device according to claim 1, characterized in that it comprises a light diffusing means provided on one of between the one or both of the inner surface and the surface of the convex lens or the LED and the convex lens. The base is circular with an opening in the center,
2. The LED illumination according to claim 1, wherein the LEDs are a plurality of surface-mounted LEDs mounted on a printed wiring board having a shape obtained by cutting a conical side surface at a plane perpendicular to an axis at different positions. apparatus. The base is circular with an opening in the center,
The LEDs are arranged in a plurality of concentric rows,
2. The LED lighting device according to claim 1, further comprising a lighting row control means for selectively lighting only a specific row of LEDs .

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