JP2011165765A - Lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting device, capable of obtaining high illuminance uniformity. <P>SOLUTION: The lighting device includes: one or more light emitting element array(s) in which a plurality of light emitting elements are arranged on a substrate on the same straight line; a plane mirror connected on the substrate in at least any one side out of both terminals of the light emitting element array perpendicularly to the arranged direction of the plurality of light emitting elements; and a double-sided mirror connected on the substrate at one or more position(s) between the plurality of light emitting elements perpendicularly to the arranged direction of the plurality of light emitting elements so that a difference between the maximum illuminance of the light emitting element array and the minimum illuminance of the light emitting element array falls within the threshold, where the double-sided mirror has a length in an irradiation direction of the light emitting element array smaller than the length of the plane mirror in the irradiation direction. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a lighting device, and more particularly to a lighting device using a linear light source.

  As a method of automatic reading of the surface of a test object such as a printed product or cards, or a print quality inspection method, the test object is moved in one direction by a transport device, and the test object is detected by using an imaging means including an imaging lens and a line sensor. There are many ways to scan the surface. In addition, depending on the apparatus, there is also a method of scanning the surface of the object to be detected by moving the imaging means in one direction with the transport device.

  Both methods require an illuminating device that irradiates light on the surface of the test object, and the illuminating device is required to have an illuminance distribution that is uniform in the arrangement direction of the light sources of the line sensors. In particular, when performing high-speed and high-precision reading or inspection, high illuminance uniformity is required to reduce the burden of image processing and signal processing.

  As such an illuminating device, an illuminating device combining a light guide using a halogen light source and an optical fiber and a light source device using a fluorescent lamp are conventionally used. In recent years, the light quantity and luminous efficiency of LEDs (Light-Emitting Diodes) have been dramatically improved, and a light source device in which LEDs are arranged in a straight line or a matrix is used (for example, Patent Document 1). reference).

  In particular, for light source devices using LEDs, it is expected to save energy by improving the light emission efficiency, reduce environmental impact by not using mercury and halogens, and make maintenance-free by taking advantage of the characteristics of long life. Has been.

JP 2007-71763 A

  However, in a light source device in which light emitting elements such as LEDs are arranged, the illuminance distribution on the test object is a distribution obtained by spatially superimposing the illuminance distributions of the respective light emitting elements. Therefore, when using a light emitting element with a highly directional light distribution obtained by integrally molding an LED and a lens, the illuminance distribution of each light emitting element forms a bell-shaped illuminance distribution in a narrow range. There is a problem that the combined illuminance distribution becomes wavy and causes non-uniform illuminance. Furthermore, since the directivity of the light emitting elements is high, unevenness in the overall illuminance distribution is likely to occur due to the positional deviation or angular deviation of the individual light emitting elements.

  On the other hand, when a light emitting element with low directivity in which the LED and the lens are not integrally molded is used, a region where one light emitting element emits light is widened. Therefore, light coming from both directions is irradiated near the center of the test object, but only light coming from one direction where the LED is present is observed near the end of the test object when viewed from the end. For this reason, the illuminance distribution is high in the vicinity of the center, and there is a problem that illuminance non-uniformity occurs in which the illuminance decreases toward the end.

As a method of preventing this illuminance non-uniformity, the light emitting element near the center reduces the light emission amount by flowing a small amount of current, and the light emitting element near the edge increases the light emission amount by flowing a large amount of current to reduce the illuminance. There is a means of balancing. However, with this method, the brightness performance of the light-emitting element cannot be exhibited sufficiently.
In addition, there is a method to increase the amount of light emission near the edge and prevent the illuminance from decreasing by making the surrounding light emitting elements dense, but it cannot physically be more dense than the size of the light emitting element alone, which increases the amount of light. There is a limit.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an illumination device that can obtain high illuminance uniformity.

  In order to solve the above-described problems, an illumination device according to the present invention includes one or more light-emitting element arrays in which a plurality of light-emitting elements are arranged on the same line on the substrate, and the substrate outside both ends of the light-emitting element array. At least one of the plane mirror connected perpendicularly to the arrangement direction of the plurality of light emitting elements, and the difference between the maximum illuminance of the light emitting element array and the minimum illuminance of the light emitting element array is within a threshold value, At least one of the plurality of light emitting elements is a double-sided mirror connected to the substrate perpendicular to the arrangement direction of the plurality of light emitting elements, and is shorter than the length of the plane mirror in the irradiation direction of the light emitting element array And a double-sided mirror having a length in the irradiation direction.

  According to the illumination device of the present invention, high illuminance uniformity can be obtained.

The figure which shows the illuminating device which concerns on 1st Embodiment. The figure which shows the simulation result of the illumination intensity distribution of the illuminating device when not using a plane mirror and a double-sided mirror. The figure which shows the simulation result of the illumination intensity distribution of the illuminating device which concerns on 1st Embodiment. The figure which shows the illuminating device which concerns on 2nd Embodiment. The figure which shows the simulation result of the illumination intensity distribution of the illuminating device which concerns on 2nd Embodiment. The figure which shows the illuminating device which concerns on 3rd Embodiment. The figure which shows the simulation result of the illumination intensity distribution of the illuminating device when not using a plane mirror and a double-sided mirror. The figure which shows the simulation result of the illumination intensity distribution of the illuminating device which concerns on 3rd Embodiment using the arrangement | positioning method of 1st Embodiment. The figure which shows the simulation result of the illumination intensity distribution of the illuminating device which concerns on 3rd Embodiment using the arrangement | positioning method of 2nd Embodiment.

(First embodiment)
Hereinafter, an illumination device according to an embodiment of the present invention will be described in detail with reference to the drawings. Note that, in the following embodiments, the same numbered portions are assumed to perform the same operation, and repeated description is omitted.
The illumination device according to the first embodiment will be described in detail with reference to FIG.
The illumination device 100 according to the first embodiment includes a substrate 101, a light emitting element 102, a plane mirror 103, and a double-sided mirror 104.

  The substrate 101 may be any substrate as long as it can fix the light emitting element 102 so that the test object 106 can be irradiated with light and can supply power.

  The light emitting element 102 is, for example, an LED, and is connected to the substrate 101 as a light emitting element array 105 including a plurality of light emitting elements 102 with the light emitting elements 102 arranged at equal intervals. In the example of FIG. 1, five light emitting elements 102 such as a light emitting element 102-1 and a light emitting element 102-2 are arranged as the light emitting element array 105. However, the present invention is not limited to this, and a light emitting element array 105 in which n light emitting elements 102 (n is a natural number of 2 or more) is used to arrange the light emitting elements 102-1 to 102-n may be used. A plurality of light emitting element arrays 105 may be arranged in parallel.

  The plane mirror 103 is connected to the substrate 101 so as to be perpendicular to the arrangement direction of the light emitting elements 102 to the substrate outside the end of the light emitting element array 105. The plane mirror 103 has a mirror surface that faces the side where the light emitting element array 105 exists.

The double-sided mirror 104 is a plane mirror whose both surfaces are mirror surfaces, and is connected to the substrate 101 between the light emitting elements 102 on the end side of the light emitting element array 105 so as to be perpendicular to the arrangement direction of the light emitting elements 102. In the example of FIG. 1, the double-sided mirror 104 is disposed between the light emitting element 102-1 that is the outermost of the light emitting elements 102 of the light emitting element array 105 and the light emitting element 102-2 that is the second position from the outside. Has been. Further, the length of the double-sided mirror 104 in the irradiation direction of the light emitting element array 105 is made shorter than that of the plane mirror 103. The reason for this is that if the length of the light emitting element 102 in the irradiation direction of the double-sided mirror 104 is made longer than that of the plane mirror 103, the light directed from the light emitting element 102 near the center of the light emitting element array 105 to the end of the light emitting element array 105 is This is because the mirror 104 is excessively blocked, and the illuminance at the end is conversely reduced.
The position where the double-sided mirror 104 is connected to the substrate 101 is preferably disposed, for example, in the vicinity of an intermediate point between the light emitting element 102-1 and the light emitting element 102-2 because the influence of heat radiation can be balanced. Furthermore, the arrangement near the intermediate point is also preferable in order to prevent structural interference between the means for holding the mirror and the light emitting element 102. Actually, the difference between the maximum illuminance of the light emitting element array 105 and the minimum illuminance of the light emitting element array 105 is within a threshold value in consideration of the size of the light emitting element 102, the width of light distribution, and the interval at which the light emitting elements 102 are arranged. The double-sided mirror 104 may be connected to an appropriate position between the light emitting elements 102. That is, in the example of FIG. 1, the double-sided mirror 104 is disposed between the light emitting element 102-1 and the light emitting element 102-2. If the difference between the maximum illuminance and the minimum illuminance is within a threshold value, the light emitting element 102 is used. The double-sided mirror 104 may be disposed between the light emitting element located at the third position from the outer side.
In addition, the larger the size of the double-sided mirror 104, the higher the effect. However, since the distance between the object 106 to which light is irradiated and the light emitting element 102 is actually finite and the size of the entire illumination device 100 is also finite, the size of the double-sided mirror 104 satisfies these conditions. Thus, an appropriate size may be selected so as to be shorter than the length of the plane mirror 103 in the irradiation direction of the light emitting element array 105.

By arranging the plane mirror 103 and the double-sided mirror 104 in this way, several patterns can be considered as light irradiated on the test object 106. For example, of the light emitted from the light emitting element 102, the light directly irradiated on the test object 106, the light reflected by the plane mirror 103 and irradiated on the test object 106, and reflected by the double-sided mirror 104 and the test object There is light irradiated onto the object 106 and light irradiated onto the test object 106 after being reflected a plurality of times by the plane mirror 103 and the double-sided mirror 104.
If the plane mirror 103 and the double-sided mirror 104 are not installed, these lights are not irradiated on the test object 106, or for example, the light emitting element 102 at the end of the light emitting element array 105 is directly below the other end. The vicinity of the upper surface of a certain test object 106 is irradiated, and sufficient illuminance cannot be obtained on the upper surface of the test object 106 immediately below this end. However, in the present embodiment, by arranging the plane mirror 103 and the double-sided mirror 104, the test object located immediately below the light-emitting element 102 near the end of the light-emitting element array 105 due to the effect of the combination mirror by the plane mirror 103 and the double-sided mirror 104. The surface on 106 can be illuminated. As a result, the illuminance distribution near the end can be prevented from being lowered, and the overall illuminance uniformity can be improved.
Note that the plane mirror 103 and the double-sided mirror 104 may be connected to either one end of the light emitting element array 105. When two or more light emitting element arrays 105 are arranged in parallel, a plane mirror is connected to the two or more light emitting element arrays 105 and a double-sided mirror 104 is provided between the light emitting elements 102 as in the case of one light emitting element array 105. Just connect. At this time, the number of the plane mirrors 103 and the double-sided mirrors 104 may be plural, as in the state in which a plurality of lighting devices 100 each having the plane mirror 103 and the double-sided mirror 104 connected to one light emitting element array 105 are arranged in parallel. 103 and the double-sided mirror 104 may be connected across two or more light-emitting element arrays 105.

The effect shown above is demonstrated with reference to FIG. 2 and FIG. 3 which are the simulation results of the illumination distribution of the illuminating device 100 which concerns on 1st Embodiment.
FIG. 2 shows the illuminance distribution of the illumination device 100 when the plane mirror 103 and the double-sided mirror 104 are not installed. The horizontal axis represents the relative position in the arrangement direction of the light emitting elements 102 and is represented by the relative position from “0.00” indicating the end of the light emitting element array 105 to the center “0.50” of the light emitting element array 105. . Specifically, when the distance from the end of the light emitting element array 105 toward the center of the light emitting element array 105 is X and the length of the entire light emitting element array 105 is L, the relative position is calculated by calculating X / L. To do. The vertical axis represents the relative illuminance of the lighting device 100, and the maximum value is 1. As shown in FIG. 2, the relative illuminance gradually decreases from the center of the light emitting element array 105 toward the end of the light emitting element array 105, and the relative illuminance of the light emitting element array 105 decreases to about 0.72.
On the other hand, FIG. 3 shows the illuminance distribution of the illumination device 100 when the plane mirror 103 and the double-sided mirror 104 are installed. As shown in FIG. 3, by installing the plane mirror 103 and the double-sided mirror 104, the characteristic that the relative illuminance near the end of the light emitting element array 105 is reduced is improved, and the relative illuminance near the end is about 0.84. Can be secured.

  According to the first embodiment described above, the difference between the maximum illuminance and the minimum illuminance of the light emitting element array is between the light emitting elements near the end of the light emitting element array and the flat mirror at the end of the light emitting element array. By installing the double-sided mirrors so as to be within the threshold value, it is possible to prevent a decrease in relative illuminance at the end of the light emitting element array, and high illuminance uniformity can be obtained.

(Second Embodiment)
The illumination device according to the second embodiment is substantially the same as the illumination device 100 according to the first embodiment, but the arrangement of the double-sided mirror 104 is different.
An illumination device 400 according to the second embodiment will be described with reference to FIG.
In the case of the double-sided mirror 104 according to the first embodiment, the double-sided mirror 104 is arranged so as to be exactly in the middle between the light-emitting elements 102. Taking FIG. 1 as an example, an intermediate point between the light-emitting elements 102-1 and 102-2. Is arranged on a straight line AA ′ passing through. On the other hand, the double-sided mirror 104 according to the second embodiment is disposed closer to the light emitting element 102-1 than the straight line AA ′ as shown in FIG. 2.

  By doing in this way, the light which goes to the center of the to-be-tested object 106 from the light emitting element 102 near the edge part of the light-emitting element array 105 is compared with the case where the double-sided mirror 104 is arrange | positioned on straight line AA '. It can collect on the surface near an edge part, and can improve illuminance uniformity as a whole. Further, even when the illumination device 400 is combined with a condensing means such as a cylindrical cylindrical lens or a reflecting mirror along the light emitting element array 105, the illuminance uniformity is further improved even when the irradiated beam is focused. Can do.

The effect shown above is demonstrated with reference to FIG. 5 which is a simulation result of the illumination distribution of the illuminating device 400 which concerns on 2nd Embodiment.
As shown in FIG. 5, the relative illuminance near the end of the light emitting element array 105 is about 0.90, which is higher than the relative illuminance near the end shown in FIG. Further, since the relative illuminance is 0.90 or more in the entire light emitting element array 105, high illuminance uniformity can be secured.

  According to the second embodiment described above, the illuminance uniformity is further improved by arranging the double-sided mirror on the light emitting element side at the end of the light emitting element array rather than the intermediate point between the light emitting elements. Can do.

(Third embodiment)
The third embodiment is different from the first embodiment and the second embodiment in that the plane mirror 103 and the double-sided mirror 104 are used at both ends of the illumination device, respectively.

  Here, as an example, FIG. 6 shows an illumination device 600 when the plane mirror 103 and the double-sided mirror 104 are arranged at both ends using the method for arranging the plane mirror 103 and the double-sided mirror 104 according to the first embodiment. In addition, it can arrange | position similarly also with the arrangement | positioning method of the plane mirror 103 and the double-sided mirror 104 which concern on 2nd Embodiment. Note that the arrangement method of the plane mirror 103 and the double-sided mirror 104 according to the first embodiment is used at one end of the illumination device, and the plane mirror 103 and the double-sided mirror 104 according to the second embodiment are used at the other end. The arrangement method may be used.

  A simulation result of the illuminance distribution of the illumination device 600 according to the third embodiment will be described with reference to FIGS. 7, 8, and 9. 7 to 9 is a relative position from one end portion of the light emitting element array 105 to the opposite end portion, and therefore, from “0.00” to “1.00”. ing.

  FIG. 7 shows a case where the plane mirror 103 and the double-sided mirror 104 are not installed at both ends of the lighting device. As shown in FIG. 7, the relative illuminance at both ends of the lighting device is considerably reduced as compared with the vicinity of the center of the light emitting element array.

  FIG. 8 shows a case where the installation method of the plane mirror 103 and the double-sided mirror 104 according to the first embodiment is used at both ends of the illumination device (illumination device 600). As shown in FIG. 8, the decrease in relative illuminance at both ends of the light emitting element array 105 is improved, and a relative illuminance of about 0.84 can be secured near the ends.

  Further, FIG. 9 shows a case where the installation method of the plane mirror 103 and the double-sided mirror 104 according to the second embodiment is used at both ends of the lighting device, and a relative illuminance of about 0.90 can be secured near the ends.

  According to the third embodiment described above, the illuminance uniformity is improved as a whole of the lighting device by disposing the plane mirror and the double-sided mirror according to the first and second embodiments at both ends of the lighting device. be able to.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

DESCRIPTION OF SYMBOLS 100,400,600 ... Illuminating device, 101 ... Board | substrate, 102, 102-1, 102-2 ... Light emitting element, 103 ... Plane mirror, 104 ... Double-sided mirror, 105 ... Light emission Element array, 106 ... test object.

Claims (5)

One or more light emitting element arrays in which a plurality of light emitting elements are arranged on the same line on the substrate;
A plane mirror connected to at least one of the substrates outside both ends of the light emitting element array perpendicularly to the arrangement direction of the plurality of light emitting elements;
The substrate perpendicular to the arrangement direction of the plurality of light emitting elements is set to one or more between the plurality of light emitting elements such that a difference between the maximum illuminance of the light emitting element array and the minimum illuminance of the light emitting element array is within a threshold value. A double-sided mirror connected to the light-emitting element, the double-sided mirror having a length in the irradiation direction shorter than a length of the plane mirror in the irradiation direction of the light emitting element array.   The lighting device according to claim 1, wherein the double-sided mirror is connected to the end side with respect to an intermediate point between the light emitting elements.   The double-sided mirror is connected between the outermost first light-emitting element and the second light-emitting element located at the second position from the outside among the plurality of light-emitting elements in the arrangement direction, or the second The lighting device according to claim 1, wherein the lighting device is connected between the light emitting element and a third light emitting element at a third position from the outside.   The plane mirror is connected to the substrate outside the both ends of the light emitting element array, and the double-sided mirror is a light emitting element disposed at both ends of the light emitting element array and one light emitting element disposed closer to the center than the light emitting element. The lighting device according to any one of claims 1 to 3, wherein the lighting device is connected to the substrate between the elements.   When two or more light-emitting element arrays are arranged in parallel, the plane mirror and the double-sided mirror are connected to a plane perpendicular to a plane stretched by the two or more light-emitting element arrays and light emitted from the light-emitting elements. The lighting device according to any one of claims 1 to 4, wherein the lighting device is characterized.

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