JP2005310680A - Light-emitting diode lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting diode lighting device capable of spreading light irradiated from a light-emitting diode chip in one direction without the unevenness of brightness by controlling light distribution by using another member. <P>SOLUTION: A recessed part 3 opening long in one direction is fitted in a recess at a base stand 4, and light-emitting diodes 2 are arranged at a center in the length direction of the recessed part 3 at the bottom face of the recessed part. On the inner face of the recessed part 3, a light-reflecting face 9 is formed reflecting light from the light-emitting diode chips and irradiating it from the open face of the recessed part 3. At the center in the length direction of the recessed part 3, a pair of reflecting protruded parts 10 protruding into the recessed part from both inner side faces in the width direction of the recessed part 3 are formed. Each reflecting protruded part 10 has its periphery face formed in an arc shape at a cross section parallel with the open face of the recessed part 3, and is set in a dimension to lessen a brightness difference in the length direction of the recessed part 3 by reflecting the light from the light-emitting diode chips 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a light-emitting diode illuminating device that controls light distribution of light emitted from a light-emitting diode chip using a separate member.

  In recent years, lighting fixtures using light-emitting diodes as a light source have increased, and as shown in FIG. 7, for example, even in lighting fixtures that illuminate the illumination surface 20 that is one surface of the light guide plate 18 in the thickness direction, There is something used. The technique of surface emitting light from the light guide plate 18 using a light emitting diode as a light source is also used for the foot lamp (Japanese Patent Application No. 2004-028490) previously filed by the present applicant. In this type of lighting fixture, light is incident over substantially the entire length in the longitudinal direction of the incident surface 19, which is one peripheral surface intersecting the illumination surface 20 in the light guide plate 18 in order to cause the illumination surface 20 of the light guide plate 18 to emit light. Therefore, a light emitting diode bare chip (hereinafter referred to as “LED chip”) 2 arranged in the longitudinal direction of the incident surface 19 has been proposed (see, for example, Patent Document 1).

  By the way, since the LED chip 2 is a point light source, if the arrangement density of the LED chips 2 is low, the incident light quantity from the vicinity of the LED chip 2 on the incident surface 19 of the light guide plate 18 as shown in FIG. As a result, a region H having a high brightness is intensively generated on the illumination surface 20, resulting in uneven brightness in the light emitted from the illumination surface 20. In order to realize surface light emission with less luminance unevenness, a method of preventing luminance unevenness of light incident on the incident surface 19 and a method of preventing luminance unevenness of light emitted from the illumination surface 20 are conceivable.

The former method can be realized by arranging the LED chips 2 at a high density so that luminance unevenness does not occur in the longitudinal direction of the incident surface 19, but the problem is that the number of LED chips 2 to be used increases and the cost increases. There is. On the other hand, as the latter method, as shown in FIG. 7, it is proposed to superimpose a prism sheet 21 that diffuses and transmits light on the illumination surface 20 of the light guide plate 18.
Japanese Patent Laid-Open No. 11-353920 (2nd page, FIG. 1)

  However, if the light emitted from the illumination surface 20 is diffused and transmitted by the prism sheet 21, the direction of the light emitted from the illumination surface 20 cannot be controlled. This method cannot be used for a lighting fixture such as a foot lamp that emits light obliquely downward from the light guide plate 18. That is, the prism sheet 21 cannot be used in a lighting fixture that controls the direction of light emitted from the light guide plate 18.

  Therefore, the former which prevents uneven brightness of light incident on the incident surface 19 by distributing the light emitted from each LED chip 2 by another member and spreading it in one direction (that is, the longitudinal direction of the incident surface 19). It is desired to realize this method with a small number of LED chips 2.

  The present invention has been made in view of the above reasons, and provides a light-emitting diode illuminating device capable of spreading light in one direction without uneven brightness by controlling the light distribution of light emitted from the light-emitting diode chip with a separate member. The purpose is to do.

  According to a first aspect of the present invention, there is provided a base in which a recess having a long opening in one direction is provided, a light emitting diode chip disposed on a bottom surface of the recess at a central portion in the longitudinal direction of the recess, A light reflecting surface formed on the peripheral surface for reflecting the light from the light emitting diode chip to emit the light from the light emitting diode chip from the opening surface, and the base is a recess at the center in the longitudinal direction of the recess A pair of reflecting protrusions projecting into the recesses from both inner side surfaces in the width direction, and each reflecting protrusion is formed in an arc shape in a cross section parallel to the opening surface. The dimensions are set so as to reduce the luminance difference in the longitudinal direction of the recess by reflecting light.

  According to this configuration, the recess is opened long in one direction so that the region from which light is extracted from the light emitting diode chip is formed in an elongated shape, and the light from the light emitting diode chip is reflected by the reflecting protrusion. The luminance difference in the longitudinal direction can be reduced. That is, it is possible to prevent the central portion, which is the peripheral portion of the light emitting diode chip, from intensively increasing in the longitudinal direction of the recess by a simple configuration of forming the reflection protrusion on the base, and from the light emitting diode chip. Light can be spread in the longitudinal direction of the recess without uneven brightness.

  Note that the shape and size of the reflection protrusion are designed based on the shape of the recess, the position of the light emitting diode chip, and the like.

  According to a second aspect of the present invention, in the first aspect of the present invention, the recess is filled with a light-transmitting resin having a flat surface, and both end portions in the longitudinal direction of the recess in the light reflecting surface, The region where the light emitted from the light-emitting diode chip and totally reflected by the surface of the translucent resin reaches is emitted from the surface of the translucent resin by being totally reflected by the surface of the translucent resin. It is inclined with respect to the surface of the translucent resin so as to reflect at an angle.

  According to this configuration, light from the light emitting diode chip that is totally reflected on the surface of the translucent resin and propagates to both ends in the longitudinal direction of the recess is emitted from the opening surface of the recess with a relatively small number of reflections. Therefore, as compared with the case where light reflection is repeated many times between the translucent resin and the bottom surface of the recess, there is an advantage that the attenuation of light in the recess can be prevented and the light use efficiency is improved.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, incident light into which one surface in the thickness direction is an illumination surface and light emitted from the recess is introduced into one of the peripheral surfaces intersecting the illumination surface is provided. A light guide plate as a surface, the base and the light guide plate are arranged so that the longitudinal direction of the recess coincides with the longitudinal direction of the incident surface, and two light emitting diodes having different emission colors as the light emitting diode chip A chip is provided, and both light emitting diode chips are arranged side by side in the width direction of the recess.

  According to this configuration, both the light emitting diode chips are arranged in the width direction of the incident surface of the light guide plate and in the direction intersecting the illumination surface, so that light from both light emitting diode chips is likely to be mixed in the light guide plate. It is possible to prevent color unevenness from occurring on the illumination surface of the light guide plate.

  In the present invention, the recess is elongated in one direction so that a region for extracting light from the light emitting diode chip is formed in an elongated shape, and the light from the light emitting diode chip is reflected by the reflecting protrusions in the longitudinal direction of the recess. To reduce the luminance difference. That is, it is possible to prevent the central portion, which is the peripheral portion of the light emitting diode chip, from intensively increasing in the longitudinal direction of the recess by a simple configuration of forming the reflection protrusion on the base, and from the light emitting diode chip. There is an advantage that light can be spread in the longitudinal direction of the recess without uneven brightness.

  As shown in FIGS. 1 and 2, the light-emitting diode illuminating device 1 according to the present embodiment includes a base 4 in which a recess 3 in which an LED chip 2 that is a bare chip of a light-emitting diode is mounted is provided on the front surface. . Although the rectangular parallelepiped base 4 is illustrated in FIG. 2, the shape of the base 4 is appropriately designed depending on the application.

  The recess 3 is long in the left-right direction in FIG. 1A, and the inner surface is inclined with respect to the front surface of the base 4 so as to widen the cross-sectional area of the recess 3 from the bottom surface toward the opening surface. ing. The left and right inner side surfaces of the recess 3 are each formed of a curved surface whose cross section parallel to the opening surface is arcuate so as to reduce the left and right dimensions of the recess 3 at the upper and lower ends of the recess 3. The bottom surface of the intermediate portion in the longitudinal direction of the recess 3 is a rectangular plane (hereinafter referred to as “mounting surface”) 5 that is parallel to the opening surface and long in the left-right direction, and the mounting surface 5 has a conductor made of a lead frame. 6 is provided. One end of the LED chip 2 is fixed to the left conductor 6 by die bonding so that the LED chip 2 emits light when the conductor 6 is energized. Connected to the body 6. That is, the LED chip 2 is mounted on the mounting surface 5 so as to be electrically connected to the conductor 6. In the present embodiment, two LED chips 2 having different emission colors are mounted on one mounting surface 5, and both the LED chips 2 are arranged side by side on the center line in the left-right direction of the recess 3. . Here, one LED chip 2 is arranged at the center between the upper edge of the mounting surface 5 and the vertical center line, and the other LED chip 2 is positioned at the center between the lower edge of the mounting surface 5 and the vertical center line. It is arranged.

  Moreover, as shown in FIG.1 (b) and FIG.1 (c), the translucent resin 7 is filled in the recess 3 in the form which makes a front surface (surface) correspond to an opening surface. That is, the surface 8 (hereinafter referred to as “light exit surface”) 8 of the translucent resin 7 is formed in a planar shape that is flush with the front surface of the base 4 and parallel to the mounting surface 5. The translucent resin 7 is preferably a transparent epoxy resin. A light reflecting surface 9 that reflects light from the LED chip 2 so as to be emitted from the emitting surface 8 is formed on the inner peripheral surface of the recess 3. The light reflecting surface 9 is a regular reflecting surface. Here, the inclination angle of the inner surface of the recess 3 with respect to the emission surface 8 is set for each part so that light directly incident from the LED chip 2 is reflected toward the emission surface 8 at an angle at which the light is emitted from the emission surface 8. Is done.

  By the way, the base 4 of this embodiment can reduce the brightness | luminance difference in the left-right direction of Fig.1 (a) which is the longitudinal direction of the recess 3 by providing the reflective protrusion 10 demonstrated below.

  The reflection protrusion 10 protrudes into the recess 3 from both the upper and lower inner surfaces at the center in the left-right direction of the recess 3 and is formed in a shape in which the peripheral surface is arcuate in a cross section parallel to the opening surface of the recess 3. The light from the LED chip 2 is reflected in the same manner as the light reflecting surface 9. In the present embodiment, as shown in FIG. 2, a radius R centered at each point P on the upper and lower sides (upper left and lower right in FIG. 2) of the recess 3 on the center line in the left-right direction of the recess 3. A virtual cylinder with the bottom of the circle is set, and a part of the virtual cylinder protrudes into the recess 3 to form the reflection protrusion 10. The distance between the upper and lower reflection protrusions 10 is substantially equal to the vertical dimension of the mounting surface 5, and the peripheral surface of the reflection protrusion 10 is orthogonal to the mounting surface 5.

  The reflection protrusion 10 reflects light from the LED chip 2 in the right direction in the right half in FIG. 1A, and reflects light from the LED chip 2 in the left direction in the left half (FIG. 1A). ) Is illustrated with an arrow A). Moreover, since the peripheral surface of the reflection protrusion 10 is curved and the light reflection angle continuously changes in the left-right direction, the light from the LED chip 2 is distributed substantially evenly in the left-right direction of the recess 3. Can be made. As a result, the luminance difference in the left-right direction of the recess 3 can be reduced. The shape and dimensions of the reflection protrusion 10 are appropriately designed so as to minimize the luminance difference in the left-right direction of the recess 3 based on the shape of the recess 3 and the arrangement of the LED chips 2.

  By the way, a part of the light dispersed in the left-right direction by the reflection protrusion 10 is at an angle exceeding the critical angle of the translucent resin 7 with respect to the emission surface 8 which is a boundary surface between the translucent resin 7 and air. Incident light is transmitted to the left and right ends of the recess 3 by being totally reflected by the exit surface 8. Here, assuming that the bottom surface of the recess 3 is parallel to the output surface 8 across both right and left ends as shown in FIG. 3, the light from the LED chip 2 is transmitted on both the output surface 8 and the bottom surface of the recess 3. The total reflection is repeated (see arrow B in FIG. 3), and the light is attenuated before being emitted from the emission surface 8, which may reduce the light use efficiency.

  Therefore, for example, as shown in FIG. 4, the angle at which the light from the LED chip 2 totally reflected by the emission surface 8 is emitted from the emission surface 8 at the left and right ends of the recess 3 (the critical angle of the translucent resin 7). It is conceivable that a part of the bottom surface (hereinafter referred to as “inclined surface”) 11 is inclined with respect to the emission surface 8 so as to be reflected toward the emission surface 8 at a smaller angle. Only the part where the light from the LED chip 2 reaches after being totally reflected by the emission surface 8 may be the inclined surface 11, and the mounting surface of the both inclined surfaces 11 where the light totally reflected by the emission surface 8 does not reach. Each end on the 5 side is cut off. Each inclined surface 11 is inclined so as to approach the emitting surface 8 toward the left and right end edges of the recess 3.

  In this way, with a part of the bottom surface of the recess 3 as the inclined surface 11, the light from the LED chip 2 totally reflected by the emission surface 8 is reflected by the inclined surface 11 and emitted from the emission surface 8 (see arrow C). Thus, if the light once totally reflected by the exit surface 8 is not totally reflected again by the exit surface 8 and the attenuation of the light in the recess 3 is prevented, the recess 3 is formed by the reflecting projection 10. When the light dispersed in the left-right direction is totally reflected by the exit surface 8 and propagates to the left and right ends of the recess 3, it can be emitted from the exit surface 8 with almost no attenuation.

  The inclination angle of the inclined surface with respect to the emission surface 8 is set in the left-right direction which is the longitudinal direction of the recess 3 so that the light totally reflected by the emission surface 8 is reflected toward the emission surface 8 so as to be emitted from the emission surface 8. It is desirable to set for each part. Therefore, in this embodiment, as shown in FIG. 5, two inclined surfaces 11a and 11b having different inclination angles are formed at the left and right end portions of the recess 3, respectively, and light is reflected in the left-right direction of the bottom surface. The angle is changed (see arrow C and arrow D).

  By the way, when an inclined surface is formed in front of the light emitting portion of the LED chip 2 (that is, closer to the emission surface 8), direct light to the light reflecting surface 9 which is the left and right inner surfaces of the recess 3 is reflected by the inclined surface. Sometimes. This light is reflected by the inclined surface, then reflected by the left and right inner surfaces of the recess 3 and emitted from the emission surface 8 (see arrow F in FIG. 4). On the other hand, in this embodiment, the distance from the emission surface 8 is increased toward the left and right end edges of the recess 3 between the inclined surface 11a and the inclined surface 11b at the left and right end portions of the recess 3, respectively. By providing each step 13, both inclined surfaces 11a and 11b are accommodated behind the light emitting portion of the LED chip 2, and direct light from the left and right inner surfaces is emitted from the emission surface 8 by one reflection. (See arrow E in FIG. 5). In short, the light from the LED chip 2 is emitted from the emission surface 8 with the least number of reflections, thereby preventing the attenuation of the light in the recess 3 and improving the light utilization efficiency. When the left and right dimensions of the recess 3 are further increased, the level difference 13 may be increased to increase the number of inclined surfaces at the left and right ends of the recess 3, respectively.

  Below, the light source X for illumination comprised using the light emitting diode illuminating device 1 mentioned above is demonstrated with reference to FIG. The illumination light source X is designed as a light source for a lighting fixture that emits light from an illumination surface 20 that is one surface in the thickness direction of the light guide plate 18 as shown in FIG. In order to allow light to enter substantially the entire length in the longitudinal direction of the incident surface 19 that is one of the intersecting circumferential surfaces, the three recesses 3 described above are arranged in the left-right direction in FIG. It is recessed side by side. Furthermore, each recess 3 is formed long in the left-right direction of FIG. 6A so that the longitudinal direction of each recess 3 coincides with the longitudinal direction of the incident surface 19. Here, the base 4 is made of a synthetic resin and is integrally formed with a lead frame constituting the conductor 6 provided on the bottom surface of the recess 3.

  The base 4 extends downward in FIG. 6A and has a shape that can be mounted on the substrate 14. A plurality of terminals 15 electrically connected to the respective conductors 6 protrude from the lower end surface of the base 4 in a line in the left-right direction. Furthermore, leg portions 16 projecting forward from the front surface where the recesses 3 are recessed are respectively extended at the left and right end portions of the lower end portion of the base 4. The bosses 17 whose peripheral surfaces are formed in an arc shape in a cross section parallel to the lower end surface protrude downward.

  According to this configuration, since the light from each LED chip 2 arranged in each recess 3 can be spread almost uniformly in the longitudinal direction of the incident surface 19, there is almost no uneven luminance on the incident surface 19. In addition, it is possible to realize surface light emission with less luminance unevenness on the illumination surface 20.

  Furthermore, as described above, the LED chips 2 of two colors different in emission color are arranged side by side in the width direction of the recess 3 (that is, the width direction of the incident surface 19). The light beams from both LED chips 2 are likely to be mixed in the light guide plate 18 and the uneven color on the illumination surface 20 of the light guide plate 18 can be eliminated.

The structure of embodiment of this invention is shown, (a) is a front view, (b) is a cross-sectional view of (a), (c) is a longitudinal cross-sectional view of (a). It is a perspective view same as the above. It is explanatory drawing which shows a light guide state in case the bottom face of a recess is parallel to an output surface. It is explanatory drawing which shows a light guide state at the time of making a part of bottom face of a recess into an inclined surface. It is explanatory drawing which shows a light guide state same as the above. The light source for illumination using the light emitting diode illuminating device same as the above is shown, (a) is a front view, (b) is a side view, and (c) is a bottom view. It is a perspective view which shows the structure which surface-emits the illumination surface of a light-guide plate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light emitting diode illuminating device 2 LED (light emitting diode) chip 3 Recess 4 Base 7 Translucent resin 9 Light reflection surface 10 Reflection protrusion 18 Light guide plate 19 Incident surface 20 Illumination surface

Claims (3)

  A base having a recess that opens long in one direction, a light emitting diode chip disposed on the bottom surface of the recess at the center in the longitudinal direction of the recess, and a light emitting diode formed on the inner peripheral surface of the recess A light reflecting surface that reflects light from the chip to emit light from the light emitting diode chip from the opening surface, and the base has both inner side surfaces in the width direction of the recess at the center in the longitudinal direction of the recess. A pair of reflecting protrusions projecting into the recesses, and each reflecting protrusion is formed in an arc shape in a cross section parallel to the opening surface, and reflects the light from the light emitting diode chip. A light-emitting diode illuminating device, characterized in that dimensions are set so as to reduce a luminance difference in a longitudinal direction of the place.   The recess is filled with a light-transmitting resin having a flat surface, and both ends of the light reflection surface in the longitudinal direction of the recess are emitted from the light-emitting diode chip and on the surface of the light-transmitting resin. The region where the totally reflected light reaches is reflected on the surface of the translucent resin so that the reflected light is reflected at an angle at which the reached light is emitted from the surface of the translucent resin by being totally reflected on the surface of the translucent resin. The light-emitting diode illuminating device according to claim 1, wherein the light-emitting diode illuminating device is inclined with respect to the device.   A light guide plate is added that has one surface in the thickness direction as an illumination surface and one of the peripheral surfaces intersecting the illumination surface as an incident surface into which light emitted from the recess is introduced. The base and the light guide plate are arranged so as to match the longitudinal direction, the light emitting diode chip is provided with two light emitting diode chips having different emission colors, and both the light emitting diode chips are arranged side by side in the width direction of the recess. The light-emitting diode illuminating device according to claim 1 or 2.

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