JP2006310414A - Led lighting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an LED lighting apparatus capable of efficiently condensing a light in a linear region. <P>SOLUTION: The LED lighting apparatus has a plurality of linearly arranged LEDs 11 and a transparent column member 13 arranged on the fronts of the LEDs so that an axis runs parallel with lines tying a plurality of the LEDs 11. Light diffusion means may be fitted among the LEDs 11 and the column member. The light can be condensed efficiently in the linear region by the column member, and a bright uniform illumination is enabled. A structure is simplified and can be manufactured at a low cost, and is strengthened. The number of the LEDs can be suppressed than conventional devices, and the operating temperatures of the LEDs are lowered. Accordingly, the deterioration in a brightness due to a temperature rise can be prevented because a heat generation is also reduced by abolishing several pieces of factors, resulting stabilizing an operation. <P>COPYRIGHT: (C)2007,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 illumination for a line sensor.

Conventionally, a line sensor is used in a copying machine, a scanner, or the like. And the illuminating device which uses LED as an apparatus which illuminates the linear area | region which can be used as an illuminating device for line sensors is proposed. For example, in Patent Document 1 below, a rectangular substrate, a plurality of LED chips of different colors mounted in a line along the longitudinal direction of the substrate, and the entire LED chip are integrally covered. The LED light source device provided with the formed substantially semi-cylindrical or kamaboko-shaped transparent resin part is disclosed.
JP 2002-299697

  There is a demand for an illumination device for a line sensor to illuminate a linear region having a predetermined length and width as brightly and uniformly as possible. However, the above-described conventional illumination device has a problem that it is difficult to efficiently collect light in a linear region and the efficiency is low. An object of the present invention is to provide an LED lighting device capable of efficiently condensing light in a linear region.

  The LED lighting device of the present invention includes a plurality of LEDs arranged linearly and a transparent columnar member arranged on the front surface of the LEDs so that the central axis is parallel to a line connecting the plurality of LEDs. Is the main feature.

  Moreover, the above-described LED illumination device is also characterized in that a light diffusing means is further provided between the LED and the column member. In the LED lighting device described above, the light diffusing means is also a light diffusing sheet attached to the surface of the cylindrical member. In addition, the above-described LED illumination device is characterized in that light reflecting means is provided on a part of the periphery of the cylindrical member.

  The LED illumination device of the present invention has an effect that light can be efficiently and uniformly illuminated by a cylindrical member by efficiently collecting light on a linear region due to the above-described features. In addition, the structure is simple, can be manufactured at low cost, and is robust. Furthermore, the number of LEDs for obtaining the desired illuminance can be reduced compared to the conventional one, and the heat generation is also reduced by that amount, so that the operating temperature of the LEDs can be lowered to prevent the brightness from being lowered due to the temperature rise. Has the effect of stabilizing.

  Embodiments will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view showing the configuration of the LED lighting device of the present invention. FIG. 2 is a longitudinal sectional view showing the configuration of the LED lighting device of the present invention. The LED lighting device includes a plurality of LEDs 11 disposed inside a long rectangular parallelepiped housing 10 and a columnar member 13 disposed in front of the LEDs 11 in the housing 10.

  The housing 10 is manufactured, for example, by forming a groove in the longitudinal direction of a long rectangular parallelepiped aluminum block. By using a metal block, the heat dissipation effect is improved. The surface of the housing 10 may be anodized black to increase the heat dissipation effect.

  As the LED 11, for example, red, blue, and green single color LEDs may be alternately arranged, or one in which three colors of LEDs are mounted in one component may be used. By combining red, blue and green LEDs, a desired visible light color can be produced. Further, if there is an LED of a color required by the device, an LED of a predetermined color such as white may be employed.

  As the shape of the LED 11, a bullet-type LED with a lead wire may be used, or a chip-shaped surface-mounted LED may be used. Although it is better to arrange the LEDs 11 as linearly as possible, the arrangement of the LEDs 11 can be changed from one row to about three rows according to the illuminance required by the apparatus.

  The lead wires of the plurality of LEDs 11 are soldered to the printed circuit board 12 disposed at the bottom. The printed circuit board 12 is fixed to the housing 10, and an insulating sheet (not shown) is laid between the printed circuit board 12 and the housing 10. The LED circuit of the printed circuit board 12 is connected to a drive circuit described later.

  The cylindrical member 13 has a cylindrical shape with a circular cross section, and is disposed on the front surface of the LED 11 so that the central axis is parallel to a line connecting the plurality of LEDs 11. The material may be, for example, a transparent resin such as acrylic or glass. Since the material of the cylindrical member is available at a low cost and can be used simply by cutting, processing is easy.

  As a result of experiments by the present inventor, it has been found that the use of a cylindrical member increases the illuminance compared to the case of using a biconvex lens. It has been found that the larger the diameter of the cylinder, the higher the light collection efficiency. However, the larger the diameter, the larger the apparatus, so that the diameter should be as large as possible within the range that satisfies the requirements of the apparatus.

  The cylindrical member collects the light emitted from the LED 11 in a plane orthogonal to the central axis, but does not collect the light in a plane parallel to the central axis. Therefore, even if the LEDs are arranged at a predetermined interval. Irradiation unevenness does not occur on the irradiated surface, and uniform illuminance can be obtained. It has also been found that the use of the cylindrical member 13 increases the amount of transmitted light by several tens of percent because there is no reflection at the boundary compared to the case of using two convex lens members.

  The distance between the LED 11 and the column member 13 varies depending on the diameter of the column, the characteristics of the lens formed on the LED component (light emission angle range of the LED), the distance between the column member and the object to be illuminated, etc. The position where the illuminance is high may be determined by experiment. However, as a result of the experiment by the present inventor, the distance between the LED and the column member is preferably slightly shorter than the diameter of the column.

  FIG. 3 is a block diagram showing a drive circuit of the LED lighting device of the present invention. In the LED lighting device, a plurality of (for example, three) LEDs 11 connected in series for each color of red (R), green (G), and blue (B) are connected in parallel. The number of LEDs connected in series is arbitrary. In addition, in order to make the brightness | luminance of each LED uniform, you may put resistance further in series in a series circuit.

  Based on the control from the control circuit 25, the three variable constant current power supply circuits 22 to 24 corresponding to the respective colors pass desired currents to the LED circuits of the respective colors. The control circuit 25 controls the variable constant current power supply circuits 22 to 24 to a desired current value based on a control signal from the external control terminal 26 or manual setting using a volume or the like. By changing the current value of the LED circuit, the brightness of each color LED can be adjusted, and light of a desired color can be obtained.

  Next, a second embodiment will be described. FIG. 4 is a cross-sectional view showing the configuration of the second embodiment of the illumination device 10 of the present invention. In the second embodiment, light diffusing means is added to the first embodiment. A light diffusing sheet 14 that is a light diffusing means is attached to the curved surface of the cylindrical member 13 on the LED 11 side. The light diffusion sheet 14 is a resin sheet made of a material that diffuses light, such as milky white, and is commercially available.

  The light emitted from the LED 11 is irregularly reflected by the light diffusion sheet 14. Then, for example, on the surface of the cylindrical member 13 away from the line connecting the center of the LED and the cylindrical member, the light that is reflected in the first embodiment and does not enter the cylindrical member 13 is diffused by the light diffusion sheet due to irregular reflection by the light diffusion sheet. 13 is entered, and part of it reaches the area to be illuminated. Therefore, the illuminance increases and the uneven illuminance in the axial direction of the cylindrical member 13 is eliminated.

  Instead of attaching the light diffusion sheet 14 to the cylindrical member 13 as the light diffusion means, a flat light diffusion plate may be arranged. Further, fine irregularities may be formed by sandblasting the surface of the cylindrical member 13 or the like.

  Although the embodiments have been described above, the following modifications can be considered for the apparatus of the present invention. The side surface inside the housing 10 may be mirror-finished so that light is reflected. Further, in the cylindrical member 13, a cylindrical side surface or end surface that does not contribute to the incidence of light from the LED 11 or the emission of light to the object to be illuminated, that is, a side surface that is nearly parallel to a line connecting the central LED and the center of the cylindrical member or The light may be reflected by plating the end face or applying a paint that reflects the light.

  In the case of a long and narrow illuminating device, the illuminance is lower at both ends than at the center, so that the LED density may be increased at both ends in order to make the illuminance in the longitudinal direction uniform. In order to efficiently release the heat generated from the LED to the housing, the entire space around the LED in the groove or only the lower part of the LED may be filled with a transparent liquid or oil, resin, or the like that is solidified after pouring. .

It is a cross-sectional view which shows the structure of the LED lighting apparatus of this invention. It is a longitudinal cross-sectional view which shows the structure of the LED lighting apparatus of this invention. It is a block diagram which shows the drive circuit of the LED lighting apparatus of this invention. It is sectional drawing which shows the structure of 2nd Example of the illuminating device of this invention.

Explanation of symbols

10 Lighting device 11 LED
12 Substrate 13 Cylindrical member 15 Object to be illuminated

Claims (4)

A plurality of LEDs arranged in a straight line;
An LED lighting device comprising: a transparent columnar member disposed on a front surface of an LED so that a central axis is parallel to a line connecting a plurality of LEDs.   The LED illumination device according to claim 1, further comprising a light diffusing unit provided between the LED and the cylindrical member.   The LED lighting device according to claim 2, wherein the light diffusing means is a light diffusing sheet attached to a surface of the cylindrical member. The LED lighting device according to claim 1, wherein light reflecting means is provided on a part of the periphery of the cylindrical member.

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