JP2014225022A - Illumination device, imaging device, and portable terminal - Google Patents

Abstract

Provided are an illuminating device excellent in brightness and color rendering, an imaging device using the illuminating device, which can obtain a bright image even at a long distance and is suitable for photographing a person, and a portable device equipped with the imaging device. To do. An illumination device includes three or more light emitting elements that are arranged on a substrate and have a rectangular upper surface and side surfaces as light emitting surfaces and emit near-ultraviolet light, and a single fluorescent layer covering these light emitting elements. The three or more light emitting elements include first and second light emitting elements having one of the side surfaces facing each other across a light collecting region where the light emitting elements are not disposed, and the first and second light emitting elements. Two sides of sides shared by adjacent side surfaces of the third light emitting element are adjacent to the first light emitting element, respectively. An illumination device, wherein one side shared by matching side faces and one side shared by adjacent side faces of the second light emitting element are located facing each other. [Selection] Figure 2

Description

  The present invention relates to an illuminating device using a light emitting element such as an LED, an imaging device equipped with the illuminating device, and a portable terminal equipped with the imaging device.

  Many recent mobile phones are provided with an integrated camera, but with such a mobile phone, it is difficult to capture a clear image, particularly when the subject is dark. . The imaging performance largely depends on the brightness and color rendering properties of the flash mounted on the mobile device, but no flash that has sufficient brightness and color rendering properties to capture clear images has been found yet. Because.

  In recent years, LED flash has been attracting attention from the viewpoint of reducing the size and weight of portable terminals. As an LED flash mounted on a portable device, it is first required to be bright. For this reason, a plurality of LED chips are usually used for current flash applications. However, since a limited battery is used, it is desired to be as efficient as possible. Further, in the case of flash use, since the brightness in a certain direction, that is, the brightness in a specific direction is important, the luminous intensity (cd) is an important characteristic as a characteristic of the LED chip.

  Therefore, for the purpose of improving luminous intensity, a reflector is provided in the vicinity of the LED chip, a plurality of LED chips are annularly arranged around one LED chip (see, for example, Patent Document 1), and a plurality of LED chips. Various ideas have been made such as arranging the centers so that their centers are in a straight line (see, for example, Patent Documents 2 and 3). However, at present, LED flashes exhibiting satisfactory brightness have not yet been realized.

JP 2005-158958 A JP 2005-109212 A Japanese Patent Laid-Open No. 10-22529

  The present invention has been made in view of the circumstances as described above, and is an illuminating device excellent in brightness and color rendering, and is suitable for taking a picture of a person while using this illuminating device to obtain a bright image even at a long distance. It is an object of the present invention to provide an image pickup apparatus and a portable device equipped with the image pickup apparatus.

  In order to solve the above-described problems, a first aspect of the present invention includes three or more light-emitting elements that are disposed on a substrate and have a rectangular upper surface and side surfaces as light-emitting surfaces, and the light-emitting element includes: Provided is an illuminating device which is arranged so as to surround a light collecting region which is not arranged, and one of the side surfaces of each of the light emitting elements faces a substantially central portion of the light collecting region.

  In such an illuminating device, a cone or a frustum having an inclined surface facing one of the light emitting side surfaces of each light emitting element can be arranged in the condensing region. As the frustum or frustum, a pyramid or a frustum can be used.

  According to a second aspect of the present invention, three or more light emitting elements having a rectangular upper surface and side surfaces as light emitting surfaces are arranged on a substrate, and the three or more light emitting elements are arranged with the light emitting elements. A first light emitting element and a second light emitting element disposed on one of the side surfaces facing each other across a non-condensing region; and a third light emitting element disposed adjacent to the first and second light emitting elements; Of the sides shared by the adjacent side surfaces of the third light emitting element are respectively one side shared by the adjacent side surfaces of the first light emitting element and the adjacent side surface of the second light emitting element. Provided is an illuminating device characterized by being positioned to face one shared side.

  In such an illuminating device, one side shared by adjacent side surfaces of the first and third light emitting elements is substantially present on a vertical plane passing through the substantially central axis of the first and third light emitting elements, and the second The one side shared by the adjacent side surfaces of the third light emitting element and the third light emitting element may be substantially present on a vertical plane passing through the substantially central axis of the second and third light emitting elements.

  In the illumination device according to the first and second aspects of the present invention, a reflector can be installed around at least one of the periphery and the bottom of the region where three or more light emitting elements are arranged.

In addition, the light emitting element can emit light in the near ultraviolet light or blue.
Further, the above lighting device can be used as a flash.
According to a third aspect of the present invention, there is provided an imaging apparatus having such a flash mounted thereon.
Moreover, the 4th aspect of this invention provides the portable terminal characterized by mounting this imaging device.

  According to the illuminating device of the present invention, the plurality of light emitting elements are arranged so that the light emission from the side surface is not blocked by the adjacent or opposing light emitting elements, so that the light extraction efficiency can be greatly improved. As a result, a flash exhibiting sufficient brightness and color rendering with low power is provided, and an imaging device and a portable terminal equipped with such a flash are provided.

Sectional drawing which shows the LED flash which concerns on one Embodiment of this invention. The top view and sectional drawing which show the arrangement | sequence of the LED chip in the LED flash which concerns on the 1st Embodiment of this invention. The top view and sectional drawing which show the arrangement | sequence of the LED chip in the conventional LED flash. The characteristic view which compares and shows the emitted light intensity of the LED flash which concerns on the 1st Embodiment of this invention, and the conventional LED flash. The top view which shows the arrangement | sequence of the LED chip in the LED flash which concerns on the 2nd Embodiment of this invention. The top view which shows the arrangement | sequence of the LED chip in another conventional LED flash. The top view which shows the arrangement | sequence of the LED chip in the LED flash which concerns on the 3rd Embodiment of this invention. The top view which shows the modification of the arrangement | sequence of the LED chip shown in FIG. The top view which shows the arrangement | sequence of the LED chip in the LED flash which concerns on the 4th Embodiment of this invention.

  The best mode for carrying out the invention will be described below.

  FIG. 1 shows a general structure of a lighting device according to an embodiment of the present invention in which a plurality of LED chips are arranged as a light source. As shown in FIG. 1, in this lighting device, a plurality of LED chips 2 are arranged on the bottom surface of a recess of a base 1 having a recess opening upward, and these LED chips 2 are covered with a fluorescent layer 3. It has been broken. The upper electrode of each LED chip 2 is connected to the first electrode 5 by the first wire 4. The lower electrode of each LED chip 2 is connected to the second electrode 7 by the second wire 6.

  The fluorescent layer 3 is obtained by dispersing phosphor particles in a polymer matrix, and the LED chip 2 is made of, for example, a GaN-based semiconductor material. Instead of the LED chip, for example, a light emitting element such as a laser diode that emits light of the same wavelength may be used.

  In the illuminating device having the configuration shown in FIG. 1, electrical energy is directly converted into light energy by the LED chip 2, and this light is converted into light of a different wavelength by a phosphor contained in the fluorescent layer 3 to emit light. Works with.

  An illumination device according to a first aspect of the present invention includes a plurality of LED chips having a rectangular light emitting upper surface disposed so as to surround a light collecting region where no LED chip is disposed, and the light emitting side surface of each LED chip. Is directed to the central portion of the light condensing region.

  The corners of the rectangular light emitting top surface and the light emitting side surface of the LED chip may be rounded.

  FIG. 2 shows an arrangement of LED chips in the lighting apparatus according to the first embodiment of the first aspect of the present invention. 2A is a top view, and FIG. 2B is an AA cross-sectional view thereof. As shown in FIG. 2, four LED chips 11 a to 11 d having a rectangular cross section are arranged on the base 10 so as to surround the light collection region 12. No LED chip is arranged in the light condensing region 12. In addition, one of the light emitting side surfaces of the LED chips 11 a to 11 d faces the central portion of the light collection region 12.

  FIG. 3 shows an arrangement of LED chips in a conventional lighting device. 3A is a top view, and FIG. 3B is a sectional view taken along the line BB. In the array of LED chips shown in FIG. 3, four LED chips 21 a to 21 d having a rectangular cross section are arranged in two rows at a narrow interval on the base 20. There is no light collection region between the LED chips 21. In addition, one of the light emitting side surfaces of each of the LED chips 21a to 21d is close to and faces one of the light emitting side surfaces of the adjacent LED chips 21a to 21d.

  In general, the LED chip has a rectangular cross section, that is, a hexahedron. Luminescence occurs not only from the top but also from the side. Therefore, in order to increase the light extraction efficiency from the LED chip, how to use the light emission from the side surface is important.

  In the arrangement of the LED chips shown in FIG. 3, the strong light emission from the side surfaces of the LED chips 21a to 21d is scattered or absorbed by the adjacent LED chips 21a to 21d as shadows, and the light is taken out of the lighting device. The efficiency that can be reduced.

  On the other hand, in the illuminating device according to the first embodiment of the present invention shown in FIG. 2, the light emitting side surface facing the light collection region 12 of the LED chips 11 a to 11 d is different from the side surfaces of the other LED chips 11 a to 11 d. Since they are not close to each other, light emission is not blocked from each other, and light emission from the side surfaces can be taken out efficiently.

  The present inventors arranged four blue light emitting LED chips as shown in FIG. 2, and caused the light to emit light by passing a current of 20 mA in a state of being sealed with a silicone resin not containing a phosphor. It was measured. Similarly, four blue light emitting LED chips were arranged as shown in FIG. 3, and a current of 20 mA was passed in a state sealed with a silicone resin not containing a phosphor to emit light, and the intensity of light emission was measured. The result is shown in FIG.

  From FIG. 4, it can be seen that when the four blue light emitting LED chips are arranged as shown in FIG. 2, the emission intensity is significantly increased as compared to the case where they are arranged as shown in FIG. 3.

  FIG. 5 is a diagram showing an array of LED chips according to the second embodiment of the present invention. In the LED chip arrangement shown in FIG. 5, three LED chips 31 a to 31 c having a rectangular cross section are arranged on the base 30 so as to surround the light collection region 32. No LED chip is disposed in the light collection region 32. In addition, one of the light emitting side surfaces of each of the LED chips 31 a to 31 c faces the central portion of the light collection region 32.

  The LED chip array shown in FIG. 5 differs from the LED chip array shown in FIG. 2 in that there are no LED chips facing each other across the condensing region 32, and therefore light emitted from the side surface of the LED chip (indicated by an arrow). Is an arrangement that is completely unobstructed.

  When the number of LED chips is an odd number, an arrangement as shown in FIG. 5 is realized, and when the number is an even number, an arrangement as shown in FIG. 2 is obtained. In any case, the light extraction efficiency of the LED element is greatly improved as compared with the conventional arrangement of LED chips that are not arranged so as to surround the light collection region.

  The LED chip arrangement shown in FIG. 6 is similar to the LED chip arrangement shown in FIG. 3, in which three LED chips 41a to 41c are arranged with a narrow interval. There is no condensing region between the LED chips 41a to 41c. In such an array of LED chips, although not as much as the array of LED chips shown in FIG. 3, light from the opposite side surfaces of LED chips 41a to 41d (indicated by arrows) is blocked by the adjacent LED chips. The extraction efficiency is low.

  FIG. 7 is a diagram showing an array of LED chips according to the third embodiment of the present invention. In the LED chip arrangement shown in FIG. 7, two LED chips 51 a and 51 b having a rectangular light emitting upper surface are arranged on the base 50 with a light-collecting region 52 therebetween, and further one LED chip 51 c. However, the LED chips 51a and 51b are arranged close to each other so that the sides shared by the adjacent side faces face each other. That is, in this LED chip arrangement, in the LED chip arrangement shown in FIG. 2, the condensing region 12 is surrounded on all sides by the LED chips, whereas in the LED chip arrangement shown in FIG. The region 52 is surrounded by LED chips on three sides.

  Even in the arrangement of the LED chips as shown in FIG. 7, light from the light emitting side surfaces of the LED chips 51a to 51c is not blocked by the adjacent LED chips 51a to 51c, so that high light extraction efficiency can be obtained. .

  FIG. 8 is a modification of the arrangement of LED chips as shown in FIG. 7, and is an example in which four LED chips are arranged. In any arrangement, the light from the side surface of the LED chip is not blocked by the adjacent LED chip, so that high light extraction efficiency can be obtained.

  FIG. 9 shows an array of LED chips according to the fourth embodiment of the present invention, and shows an illuminating device in which a conical polyhedron 62 is arranged in the light collecting region 32 of the array of LED chips 31a to 31c shown in FIG. In the configuration shown in FIG. 9, light emitted from the side surfaces of the LED chips 31 a to 31 c reaches the condensing region 32, is then reflected by the conical polyhedron 62, and is emitted upward. As a result, light can be efficiently taken out of the LED chips 31a to 31c. The pyramidal polyhedron includes a cone and a frustum, the cone includes a pyramid and a cone, and the frustum includes a pyramid and a frustum.

  The conical polyhedron 62 may be made of a metal such as aluminum or a metal film deposited on the surface of a molded body such as plastic.

  Examples of the present invention and comparative examples will be shown below, and the effects of the present invention will be described more specifically. In each example, an LED flash having the structure shown in FIG. 1 was prepared, and the luminous intensity (cd) was measured by changing only the chip arrangement. For the fluorescent layer, a yellow light emitting phosphor, YAG (yttrium aluminum garnet) based phosphor dispersed at 30 wt% in a silicon polymer, and a blue light emitting (emission center wavelength = 460 nm, InGaN) LED chip was used as the LED chip. . Further, the position and characteristics of the reflector are all the same.

Example 1
Ten LED flashes having the LED chip arrangement shown in FIG. 2 were prepared. About these LED flashes, when a current of 20 mA was passed through each chip to emit light, the luminous intensity was 7.5-9.0 cd.

Comparative Example 1
Ten LED flashes having the LED chip arrangement shown in FIG. 2 were prepared. About these LED flashes, when a current of 20 mA was passed through each chip to emit light, the luminous intensity was 6.2-7.1 cd. From a comparison between this result and the result of Example 1, it was found that the luminous intensity was improved by about 27% by using the chip arrangement of Example 1 even with the same number of LED chips.

Example 2
Ten LED flashes having the LED chip arrangement shown in FIG. 5 were produced. When these LED flashes were caused to emit light by passing a current of 20 mA through each chip, the luminous intensity was 6.0 to 7.5 cd. From this result, it can be seen that although the number of LED chips is three, it was possible to obtain almost the same luminous intensity as the LED flash having four LED chips of Comparative Example 1.

Comparative Example 2
Ten LED flashes having the LED chip arrangement shown in FIG. 6 were produced. When these LED flashes were made to emit light by passing a current of 20 mA through each chip, the luminous intensity was 4.5 to 5.5 cd.

Example 3
As shown in FIG. 9, ten LED flashes were prepared in which three LED chips were arranged and a triangular pyramid-shaped polymer block having silver deposited on the surface was arranged in the light condensing region. About these LED flashes, when a current of 20 mA was passed through each chip to emit light, the luminous intensity was 6.5 to 8.0 cd.

  From this result, although the LED chip array was the same as the LED chip array of Example 2, the luminous intensity was increased as compared with the LED flash of Example 2. This is considered to be due to the fact that the light is collected in front of the LED chip by arranging the reflector in the light collecting region in addition to the effect of improving the light extraction efficiency by the arrangement of the LED chip.

  The present invention is not limited to the above-described embodiments and examples. For example, an LED chip is used as the light emitting element, but the present invention is not limited to this, and a laser diode can also be used as the light emitting element.

  In addition, 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.

1, 10, 20, 30, 40, 50 ... base, 2, 11a, 11b, 11c, 11d ... L
ED chip, 3 ... fluorescent layer, 4 ... first wire, 5 ... first electrode, 6 ... second wire, 12
, 32, 52... Condensing region, 62.

Claims (9)

  A lighting device comprising three or more light-emitting elements arranged on a substrate and having a rectangular upper surface and side surfaces as light-emitting surfaces and emitting near-ultraviolet light, and a single fluorescent layer covering these light-emitting elements, The one or more light emitting elements include first and second light emitting elements, each of which has one side surface disposed opposite to each other across a light collecting region where the light emitting elements are not disposed, and the first and second light emitting elements. Two sides of the sides shared by the adjacent side surfaces of the third light emitting element are shared by the adjacent side surfaces of the first light emitting device, respectively. The lighting device is characterized in that one side of the second light emitting element and the adjacent side surface of the second light emitting element are located facing each other.   The lighting device according to claim 1, wherein the number of the light emitting elements is three.   And a fourth light emitting element, wherein one side shared by adjacent side faces of the fourth light emitting element is one side shared by adjacent side faces of the first light emitting element, and adjacent to the second light emitting element. The lighting device according to claim 2, wherein the lighting device is positioned so as to face one side shared by matching side surfaces or one side shared by adjacent side surfaces of the third light emitting element.   One side shared by the adjacent side surfaces of each of the first and third light emitting elements is substantially present on a vertical plane passing through a substantially central axis of the first and third light emitting elements, and the second and third light emitting elements are present. The lighting device according to claim 1, wherein one side shared by the adjacent side surfaces of each of the light emitting elements substantially exists on a vertical plane passing through a substantially central axis of the second and third light emitting elements. .   5. The lighting device according to claim 1, wherein a reflecting plate is provided on at least one of a periphery and a bottom surface of a region where the three or more light emitting elements are arranged.   A flash comprising the lighting device according to claim 1.   An imaging apparatus comprising the flash according to claim 6.   A portable terminal comprising the imaging device according to claim 7.   The three or more light emitting elements are arranged so as to surround the light collection region so that light from a side surface of each light emitting element is not blocked by an adjacent light emitting element. Item 2. The lighting device according to Item 1.

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