Light source device

A light source device includes a plurality of light emitting parts, a first lens, and an optical lens. Each light emitting part is configured to emit light from the light emitting surface at a first full-width half-maximum and is configured to be individually turned on. The optical lens has a first surface including incident regions and a second surface including emission regions. A minimum distance between the first surface of the optical lens and the first lens is 0.1 mm or more and 1.0 mm or less. A light emitted from each of the light emitting parts enters the optical lens through the first lens, the light being emitted from the first lens at a second full-width half-maximum smaller than the first full-width half-maximum, such that lights emitted from two or more of the light emitting parts are irradiated to two or more corresponding irradiation regions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No. 2020-147019, filed on Sep. 1, 2020, Japanese Patent Application No. 2020-028320, filed on Feb. 21, 2020, and Japanese Patent Application No. 2020-009416, filed on Jan. 23, 2020, the contents of which are hereby incorporated by reference in their entireties.

BACKGROUND

The present disclosure relates to a light source device.

Recently, light sources including a plurality of light emitting parts, such as light emitting diodes, have been used widely. For example, Japanese Patent No. 5275557 B1 describes a light source that can be used for a flash for a small camera, such as a camera incorporated in a mobile phone.

SUMMARY

Such a light source for use in, for example, a flash for a camera, must irradiate a desired irradiation region with a sufficient amount of light, among individual irradiation regions demarcated from the whole irradiation area.

In view of this, one object of the present disclosure is to provide a light source device that can irradiate a desired irradiation region with a sufficient amount of light.

A light source device according to one embodiment of the present disclosure includes: a plurality of light emitting parts, each having an upper surface and a light emitting surface in the upper surface, each of the light emitting parts being configured to emit light from the light emitting surface at a first full-width half-maximum and being configured to be individually turned on; a first lens covering the light emitting surfaces of the plurality of light emitting parts; and an optical lens located above the light emitting surfaces of the light emitting parts, the optical lens including: a first surface located at a light emitting surface side of the light emitting part, the first surface including a plurality of incident regions each corresponding to a respective one of the light emitting parts such that a light emitted from each of the plurality light emitting parts is incident on a respective one of the plurality of incident regions, and a second surface located on an opposite side to the first surface, the second surface including a plurality of emission regions each corresponding to a respective one of the plurality of incident regions. A minimum distance between the first surface of the optical lens and the first lens is 0.1 mm or more and 1.0 mm or less. A light emitted from each of the light emitting parts enters the optical lens through the first lens, the light being emitted from the first lens at a second full-width half-maximum smaller than the first full-width half-maximum, such that lights emitted from two or more of the light emitting parts are irradiated to two or more corresponding irradiation regions.

A light source device according to another embodiment of the present disclosure includes: a plurality of light emitting parts, each having an upper surface and a light emitting surface in the upper surface, each of the light emitting parts being configured to emit light from the light emitting surfaces at a first full-width half-maximum and being configured to be individually turned on; a first lens covering the light emitting surfaces of the plurality of light emitting parts; and an optical lens located above the light emitting surfaces of the light emitting parts, the optical lens including: a first surface including a plurality of incident regions, and a second surface including a plurality of emission regions. A minimum distance between the first surface of the optical lens and the first lens is 0.1 mm or more and 1.0 mm or less. A light emitted from each of the light emitting parts enters the optical lens through the first lens, the light being emitted from the first lens at a second full-width half-maximum smaller than the first full-width half-maximum, such that lights emitted from two or more of the light emitting parts are irradiated to two or more corresponding irradiation regions.

A light source device according to still another embodiment of the present disclosure includes: a plurality of light emitting parts arranged in a matrix, each of plurality of light emitting parts having an upper surface and a light emitting surface in the upper surface, each of the light emitting parts being configured to emit light from the light emitting surface at a first full-width half-maximum and being configured to be individually turned on; a first lens covering the light emitting surfaces of the plurality of light emitting parts and an optical lens located above the light emitting surfaces of the light emitting parts, the optical lens including a first surface including a plurality of incident regions and a second surface including a plurality of emission regions. A light emitted from each of the light emitting parts enters the optical lens through the first lens, the light being emitted from the first lens at a second full-width half-maximum smaller than the first full-width half-maximum. The first lens comprises a plurality of first unit lenses, each first unit lens being provided for a respective one of the plurality of light emitting parts. The optical axis of at least one of the plurality of first unit lens tilts with respect to the optical axis of the optical lens by an angle γ. The angle γ is expressed by the formula

γ=tan-1(xL⨯tan⁡(α2)),
where L (0<L) is a minimum distance between the optical axis of the optical lens and a center of the light emitting surface of the light emitting part disposed at a corner of the matrix, x (0<x≤L) is a minimum distance between the optical axis of the optical lens and a center of the light emitting surface of the light emitting part covered with the first unit lens having the tilted optical axis, and α (0°<α<180°) is an angle formed by a straight line connecting a central point and one point of two points that are located at two diagonal corners of an area including all the irradiation regions, and a straight line connecting the central point and the other point of the two points when the center point is an intersection of a plane in which the light emitting surfaces of the plurality of light emitting parts extend and the optical axis of the optical lens, such that lights emitted from two or more of the light emitting parts are irradiated to two or more corresponding irradiation regions.

The light source device according to certain embodiments of the present disclosure can irradiate the desired irradiation region with a sufficient amount of light.

DETAILED DESCRIPTION

Hereinafter, embodiments and examples according to the present disclosure will be described below with reference to the drawings. A light source for a flash described below, which is an example of a light source device according to the present disclosure, is intended to embody the technical ideas of the invention according to the present disclosure. However, the scope of the invention is not limited to the described embodiments and examples unless otherwise specified.

In the drawings, members having an identical function may be denoted by an identical reference character. In consideration of ease of explanation or understanding of the gist of the present invention, a plurality of embodiments or examples will be described for convenience, and configurations described in different embodiments or examples can be partially interchanged or combined. In the embodiments and examples that will be described below, repeated description of previously described elements may be omitted, and only the differences may be described. In particular, similar operations and similar effects obtained from similar configurations will not be mentioned for each embodiment or example. In the drawings, the sizes and positional relationships among members may be exaggerated for the sake of clarity.

With a light source, for example, for a camera flash, the greater the number of individual irradiation regions into which the whole irradiation area is demarcated, the more finely an irradiation region irradiated with light and an irradiation region not irradiated with light can be distinguished from each other, which allows for obtaining a photograph showing a subject more clearly.

However, when the number of divisions is increased to divide the whole irradiation area into detailed irradiation regions, the area of each individual irradiation region is reduced, so that light emitted from each light emitting part is not easily condensed on a desired irradiation region using an optical lens (for example, a camera lens), resulting in difficulty in irradiating the desired irradiation region with a sufficient amount of light. The inventors have made intensive studies to solve this problem.

As a result, the inventors have found that, using another lens in addition to the optical lens, the full-width half-maximum (directional full-width half-maximum) of the light emitted from each light emitting part is made narrower, causing the light to have directivity, especially, a predetermined directivity with respect to the direction toward the desired irradiation region, and to enter the optical lens thereafter, which allows or irradiating the desired irradiation region with a sufficient amount of light.

A light source device according to an embodiment of the present disclosure has been made in view of the findings described above, so as to irradiate two or more irradiation regions with light. The light source device includes: a plurality of light emitting parts, each having an upper surface and a light emitting surface in the upper surface, each of the light emitting parts being configured to emit light from the light emitting surface at a first full-width half-maximum and being configured to be individually turned on; a first lens covering the light emitting surfaces of the plurality of light emitting parts; and an optical lens located above the light emitting surfaces of the light emitting parts, the optical lens including: a first surface located at a light emitting surface side of the light emitting part, the first surface including a plurality of incident regions each corresponding to a respective one of the light emitting parts such that a light emitted from each of the plurality light emitting parts is incident on a respective one of the plurality of incident regions, and a second surface located on an opposite side to the first surface, the second surface including a plurality of emission regions each corresponding to a respective one of the plurality of incident regions. A minimum distance between the first surface of the optical lens and the first lens is 0.1 mm or more and 1.0 mm or less. A light emitted from each of the light emitting parts enters the optical lens through the first lens, the light being emitted from the first lens at a second full-width half-maximum smaller than the first full-width half-maximum, such that lights emitted from two or more of the light emitting parts are irradiated to two or more corresponding irradiation regions.

A light source device according to another embodiment of the present disclosure also has been made in view of the findings described above, so as to irradiate two or more irradiation regions with light. The light source device includes: a plurality of light emitting parts, each having an upper surface and a light emitting surface in the upper surface, each of the light emitting parts being configured to emit light from the light emitting surfaces at a first full-width half-maximum and being configured to be individually turned on; a first lens covering the light emitting surfaces of the plurality of light emitting parts; and an optical lens located above the light emitting surfaces of the light emitting parts, the optical lens including: a first surface including a plurality of incident regions, and a second surface including a plurality of emission regions. A minimum distance between the first surface of the optical lens and the first lens is 0.1 mm or more and 1.0 mm or less. A light emitted from each of the light emitting parts enters the optical lens through the first lens, the light being emitted from the first lens at a second full-width half-maximum smaller than the first full-width half-maximum, such that lights emitted from two or more of the light emitting parts are irradiated to two or more corresponding irradiation regions.

A light source device according to another embodiment of the present disclosure also has been made in view of the findings described above, so as to irradiate two or more irradiation regions with light. The light source device includes: a plurality of light emitting parts arranged in a matrix, each of plurality of light emitting parts having an upper surface and a light emitting surface in the upper surface, each of the light emitting parts being configured to emit light from the light emitting surface at a first full-width half-maximum and being configured to be individually turned on; a first lens covering the light emitting surfaces of the plurality of light emitting parts and an optical lens located above the light emitting surfaces of the light emitting parts, the optical lens including a first surface including a plurality of incident regions and a second surface including a plurality of emission regions. A light emitted from each of the light emitting parts enters the optical lens through the first lens, the light being emitted from the first lens at a second full-width half-maximum smaller than the first full-width half-maximum. The first lens comprises a plurality of first unit lenses, each first unit lens being provided for a respective one of the plurality of light emitting parts. The optical axis of at least one of the plurality of first unit lens tilts with respect to the optical axis of the optical lens by an angle γ.

The angle γ is expressed by the formula

γ=tan-1(xL⨯tan⁡(α2)),
where L (0<L) is a minimum distance between the optical axis of the optical lens and a center of the light emitting surface of the light emitting part disposed at a corner of the matrix, x (0<x≤L) is a minimum distance between the optical axis of the optical lens and a center of the light emitting surface of the light emitting part covered with the first unit lens having the tilted optical axis, and α (0°<α<180°) is an angle formed by a straight line connecting a central point and one point of two points that are located at two diagonal corners of an area including all the irradiation regions, and a straight line connecting the central point and the other point of the two points when the center point is an intersection of a plane in which the light emitting surfaces of the plurality of light emitting parts extend and the optical axis of the optical lens, such that lights emitted from two or more of the light emitting parts are irradiated to two or more corresponding irradiation regions.

EMBODIMENTS

1. First Embodiment

Hereinafter, a light source for a flash will be described as an example of a light source device according to the present disclosure, with reference to the drawings.

A light source1for a flash according to the present embodiment is a light source configured to irradiate two or more irradiation regions with light emitted from light emitting parts. As used herein, the irradiation region is a region that is expanded radially outwardly with respect to a certain direction. In the present embodiment, two or more irradiation regions refer to individual regions whose centers are spaced apart from each other by a predetermined distance when two or more light emitting parts are individually turned on, and that have a predetermined size and are individually irradiated with light emitted from the respective light emitting parts. That is, the expression “two or more irradiation regions” does not refer to a single region irradiated with lights emitted from two or more light emitting parts, but refers to a plurality of regions individually irradiated with lights emitted from respective two or more light emitting parts. The light source1for a flash according to the present embodiment is provided with a plurality of light emitting parts corresponding to a plurality of irradiation regions onto which lights in different directions are to be irradiated, as will be described below. Thus, by selecting and turning on one or more of the plurality of light emitting parts, one or more desired irradiation regions can be irradiated with the light. As shown inFIG.1, the light source1includes a substrate2, twenty-five light emitting parts41disposed on an upper surface2aof the substrate2, a first lens10, and an optical lens30located above the light emitting parts41. The first lens10includes twenty-five first unit lenses11, each corresponding to a respective one of light emitting part41and covering a light emitting surface41ain an upper surface of each light emitting part41. The optical lens30collects or projects the light emitted from each light emitting part41toward the corresponding irradiation region.

The optical lens30has a first surface31on a light emitting surface41aside of the light emitting part41and a second surface32on an opposite side to the first surface31. The first surface31includes a plurality of incident regions33each corresponding to a respective one of the light emitting parts41and onto each of which the light emitted from the respective light emitting part41is incident. The second surface32includes a plurality of emission regions34each corresponding to a respective one of the incident regions33. The incident region33and the emission region34shown in the figure are exaggeratedly depicted to indicate the regions.

Light emitted from each of the light emitting parts41enters the optical lens30through the first lens10, is then emitted from the optical lens30, and is irradiated to a corresponding one of irradiation regions that correspond to respective light emitting parts41.

In the present embodiment, a frame3that accommodates the twenty-five light emitting parts41, the first lens10, and the optical lens30is disposed on the upper surface2aof the substrate2.

For easy understanding of an internal structure of the light source1,FIG.1shows the cross sections of the optical lens30and the frame3without illustration of portions of the optical lens30and portions of the frame3.

As used herein, for example, the expression that the first unit lens11is provided “corresponding to” the light emitting part41means that a single first unit lens11is provided in a one-to-one relationship with a single light emitting part41so that the light emitted from the single light emitting part41enters the single first unit lens11and is then emitted from the single first unit lens11toward the optical lens30. Also, for example, the emission region34“corresponding to” the incident region33refers to a region where light entering the optical lens30from a single incident region33is emitted to the outside of the optical lens30, in other words, a region provided in a one-to-one relationship with the single incident region33. Further, for example, the irradiation region “corresponding to” the light emitting part41refers to a region that is to be irradiated with the light emitted from a single light emitting part41and is provided in a one-to-one relationship with the single light emitting part41.

Thus, the term “corresponding to” herein means the relationship between members, between regions, between a member and a region, and the like, that are associated with each other.

Arrangement of Light Emitting Parts

As shown inFIG.2A, the twenty-five light emitting parts41are arranged in a matrix of five rows and five columns. The light emitting part located at the center of the twenty-five light emitting parts41(the central light emitting part50) is a light emitting part disposed in the third row and third column.

In the present embodiment, each light emitting part41(including the central light emitting part50) has a square shape in a top view, and adjacent light emitting parts41are disposed in contact with each other. The light emitting parts41may be in other appropriate shapes and arrangements. The light emitting part41may have a shape that is, for example, rectangular, circular, polygonal, etc., in a top view. For example, adjacent light emitting parts41may be disposed apart from each other. The light emitting surfaces41aof the light emitting parts41may have similar shapes in the top view. For example, as shown inFIG.2B, the size of the light emitting surfaces may be gradually reduced, like the light emitting surfaces50A1,41a1, and41a2inFIG.2B, as the distance from a central light emitting part50A increases. Alternatively, for example, as shown inFIG.2C, the size of the light emitting surfaces may be gradually increased, for example, like the light emitting surfaces50B1,41b1, and41b2inFIG.2C, as the distance from a central light emitting part50B increases. That is, the size of the light emitting surface41aof each light emitting part41may vary according to the location of the light emitting part41in the matrix arrangement. The farther the light emitting part41is disposed from the optical axis of the optical lens30, the longer the distance to the corresponding irradiation region, the more difficult to control the light distribution, and the greater the loss of light tends to be. In view of this, with an arrangement in which the farther the light emitting part41is located from the central light emitting part50B, the larger the light emitting surface of the light emitting part41, for example, as in the light emitting surfaces41b1and41b2shown inFIG.2C, the amount of light in the light emitting part41located far from the central light emitting part50B can be increased, reducing the reduction in the brightness.

Furthermore, the number of light emitting parts41may be other than twenty-five, and it is sufficient to employ two or more light emitting parts41. The arrangement of the plurality of light emitting parts41may be other than a matrix of m rows and m columns (m≥2), and, for example, may be a matrix of m rows and n columns (m≥1, n≥2, m≠n), or may be a non-matrix arrangement. For example, four light emitting parts41are arranged in two rows and two columns, twelve additional light emitting parts41may be arranged around the four light emitting parts41on four sides to form a matrix such that four light emitting parts of the twelve additional light emitting parts41are disposed on each side of the four sides, and eight further additional light emitting parts41may be disposed around the twelve additional light emitting parts41on four sides such that two light emitting parts are disposed on each side of the four sides except for corners of the matrix. Thus, the plurality of light emitting parts41can be arranged in a shape close to a circle in a plan view. With such an arrangement of the plurality of light emitting parts41, using the optical lens30having a circular shape in a plan view allows the lights from the plurality of light emitting parts41to be efficiently incident onto the optical lens30. The distance between adjacent light emitting parts41or between adjacent light emitting surfaces41amay be varied. That is, the distance between the two light emitting parts41or two light emitting surfaces41aadjacent in the row direction may be shorter than the distance between the two light emitting parts41or the two light emitting surfaces41aadjacent in the column direction.

Arrangement of Irradiation Regions

As shown inFIG.3, the light source1according to the present embodiment is configured to irradiate light to an area R1, which is divided into twenty-five irradiation regions. The area R1and each irradiation region shown in the drawings are schematically depicted two-dimensionally for ease of understanding of the contents of the invention, but can be actually a three-dimensional space. The twenty-five irradiation regions are arranged in a matrix with five rows and five columns. A single irradiation region corresponds to a single light emitting part41and is irradiated with light emitted from the corresponding light emitting part41.

While the twenty-five irradiation regions are arranged in a matrix in the present embodiment, the irradiation regions may be arranged in any other appropriate arrangement. For example, any appropriate number of irradiation regions may be provided as long as two or more irradiation regions are provided. The number of irradiation regions is desirably the same as the number of light emitting parts41. Furthermore, the arrangement of the plurality of irradiation regions may be other than a matrix of i rows and i columns (i≥2). The plurality of irradiation regions may be arranged in a matrix of i rows and j columns (i≥1, j≥2, i≠j) or may be in a non-matrix arrangement. The arrangement of the irradiation regions is desirably the same as the arrangement of the light emitting parts41.

Arrangement Relationship Between Light Emitting Part and Irradiation Region

In the present embodiment, as shown inFIG.3, each light emitting part41and its corresponding irradiation region are arranged in a point-symmetric arrangement relationship with respect to a single point O located directly above a midpoint P of a light emitting surface50aof the central light emitting part50. That is, each light emitting part41and a respective one of the irradiation regions, each of the irradiation regions being to be irradiated with a light emitted from a respective one of the light emitting parts, have the point-symmetric arrangement relationship with respect to a single predetermined point for the corresponding light emitting part41, such that the plurality of light emitting parts41and respective corresponding irradiation regions are in the point-symmetric arrangement relationship with respect to the same single predetermined point (the single point O). For example, the irradiation region R33, which is disposed in the third row and third column among the twenty-five irradiation regions, is the irradiation region corresponding to a central light emitting part50disposed in the third row and third column among the twenty-five light emitting parts41. For example, the irradiation region R35, which is disposed in the third row and fifth column among the twenty-five irradiation regions, is the irradiation region corresponding to a light emitting part55disposed in the third row and first column among the twenty-five light emitting parts41. For example, an irradiation region R42, which is disposed in the fourth row and second column among the twenty-five irradiation regions, is the irradiation region corresponding to a light emitting part60disposed in the second row and fourth column among the twenty-five light emitting parts41.

As has been described above, the light emitting part41and the corresponding irradiation region are provided in a one-to-one relationship, which is not intended to include only a configuration in which light emitted from a single light emitting part41is irradiated to only the corresponding irradiation region. The “irradiation region corresponding to the light emitting part41” refers to an irradiation region that is a target to which light emitted from the light emitting part41is to be irradiated. Therefore, in practice, an irradiation region adjacent to (or near) the irradiation region corresponding to a single light emitting part41can also be irradiated with the light emitted from the single light emitting part41. In other words, as shown inFIG.3, a single irradiation region may include a region (first irradiation region) RIA that is irradiated only with the light emitted from a corresponding light emitting part41, and a region (second irradiation region) R1B that is irradiated with the light emitted from the corresponding light emitting part41and light emitted from a light emitting part41adjacent to (and/or near) the corresponding light emitting part41. The single irradiation region may not include the first irradiation region R1A but may include only the second irradiation region R1B.

Each light emitting part41and its corresponding irradiation region are in the point-symmetric arrangement relationship with respect to the single point O in the description above, but may be in other appropriate arrangement relationship.

For example, the reference point for the point symmetry may be different for light emitting parts41. That is, each irradiation region that is irradiated with light emitted from a corresponding light emitting part41and the corresponding light emitting part41are in the point-symmetric arrangement relationship with respect to a single predetermined point for the corresponding light emitting part41. Furthermore, the single predetermined point is, for example, a single point on an optical axis B1of each of the first unit lenses11corresponding to a corresponding one of the light emitting parts41. Therefore, a light emitting part41and an irradiation region irradiated with light emitted from the light emitting part41may be in the point-symmetric arrangement relationship with respect to the single point located on the optical axis B1of a corresponding first unit lens11. The single point corresponding to each of the plurality of light emitting parts may be the same point.

For example, the reference point for the point symmetry (the single point O in the case of the present embodiment) may not be disposed directly above the midpoint P of the light emitting surface50a.

Distribution of Light Emitted from Each Light Emitting Part

Next, referring toFIG.1, a detailed description will be given on the distribution of light emitted from the light emitting part41and irradiated to a corresponding irradiation region.

Light emitted from the light emitting surface41aof a light emitting part41at a first full-width half-maximum el enters a corresponding one of the first unit lenses11, so that a full-width half-maximum of the entered light is reduced to a second full-width half-maximum θ2(θ1>θ2) by the first unit lent11. The optical axis of each of the first unit lenses11is set to be parallel or tilted with respect to an optical axis B2of the optical lens30, which allows the light to have the directivity toward the corresponding irradiation region. The light emitted from the corresponding first unit lens11enters the optical lens30through a corresponding one of the incident regions33, each corresponding to a respective one of light emitting parts41. The light entered the optical lens30is emitted from a corresponding one of the emission regions34, each corresponding to a respective one of the incident region33, to the outside of the optical lens30, and is irradiated to a corresponding irradiation region located, for example, at the position that is point-symmetric to the light emitting part41with respect to the single point O.

The single point O illustrated as an example is a point on the optical axis B2of the optical lens30, as will be described below. Accordingly, the light emitted from the central light emitting part50is emitted along the optical axis B2of the optical lens30, i.e., in a direction substantially parallel to the optical axis B2, and is irradiated to an irradiation region R33located directly above the central light emitting part50. Light emitted from light emitting parts other than the central light emitting part50travels intersecting the optical axis B2of the optical lens30, and then is irradiated to respective corresponding irradiation regions. The expression “along the optical axis of the optical lens” as used herein refers to, in particular, “through the optical axis of the optical lens.”

In the present embodiment, a light emitting part41and its corresponding irradiation region are arranged at point-symmetric positions with respect to the single point O located directly above the central light emitting part50. Thus, in the present embodiment, light emitted from the light emitting parts41other than the central light emitting part50intersect the optical axis B2of the optical lens30to be irradiated to respective corresponding irradiation regions. However, a light emitting part41that emits the light that intersects the optical axis B2of the optical lens30depends on the arrangement relationship between the light emitting parts41and the irradiation regions.

That is, in the present embodiment, lights emitted from the plurality of light emitting parts41intersect the optical axis B2of the optical lens30or pass through the optical axis B2of the optical lens30to irradiate the irradiation regions.

For the light source1according to the present embodiment, the shapes of the incident region33in the first surface31and the emission region34in the second surface32of the optical lens30are exemplified as one of the factors for irradiating irradiation regions with light emitted from corresponding light emitting parts41. More specifically, refraction of light in the incident region33and refraction of the light in the emission region34causes light emitted from a light emitting part41to be irradiated to a corresponding irradiation region. This depends on the shape of the incident region33in the first surface31and the shape of the emission region34in the second surface32.

The refraction of light in the incident region33and the refraction of light in the emission region34of the optical lens30are caused due to a difference between the refractive index of the optical lens30and the refractive index of a medium in contact with the optical lens30. For this reason, a difference between the refractive index of the optical lens30and the refractive index of the medium in contact with the optical lens30is a parameter that is also to be considered when setting the shape of the first surface31, including the incident regions33, and the shape of the second surface32, including the emission regions34, of the optical lens30. In the light source1according to the present embodiment, the medium in contact with the optical lens30is a space, in which, for example, the air is present. Therefore, in the present embodiment, the difference between the refractive index of the optical lens30and the refractive index of the medium in contact with the optical lens30is a difference in the refractive index between the optical lens30and the air.

Light enters the optical lens30through the first unit lens11. Therefore, the light distribution characteristic of the first unit lens11is also a factor for irradiating the corresponding irradiation region with the light emitted from the light emitting part41. More specifically, an emitting direction (directivity) of the light emitted from the first unit lens11is a factor for irradiating the corresponding irradiation region with the light emitted from the light emitting part41. The emission direction determines the direction of the optical axis of each first unit lens11.

Such irradiation of the corresponding irradiation region with the light emitted from the light emitting part41depends on the shapes of the first surface31and the second surface32of the optical lens30. The difference between the refractive index of the optical lens30and the refractive index of the medium in contact with the optical lens30is also a parameter that can be set for determining the shape of the first surface31and the shape of the second surface32of the optical lens30. Further, because light entering the optical lens30is light emitted from the first unit lens11, an emitting direction of the light emitted from the first unit lens11can also be a parameter for determining the shape of the first surface31and the shape of the second surface32of the optical lens30.

Thus, the shape of each of the incident region33and the emission region34, which is one of the factors for irradiating the corresponding region with the light emitted from the light emitting part41, is determined, for example, by simulation, in consideration of the parameters exemplified above.

Components of the light source will be described in detail below with reference toFIGS.1,4A and5.

Substrate

The substrate2is a wiring substrate including connection electrodes on the upper surface2a. Each of the connection electrodes is connected to a respective one of electrodes44of the light emitting parts41, which will be described below.

Frame

As shown inFIGS.1and4A, the frame3is disposed on the upper surface2aof the substrate2. The frame3is a member with a hollow interior and an opening in an upper portion that communicates with the hollow interior. The frame3preferably includes, at its inner surface, a light-absorbing member that does not reflect light. The light-absorbing member is formed of, for example, polycarbonate, silicone resin, polyphenylene sulfide (PPS), polyamide (PA), or liquid crystal plastic (LCP). The whole frame3may be made of the light-absorbing member. The light emitting parts41, the first lens10, and the optical lens30are disposed in the hollow interior of the frame3.

The height between the upper surface2aof the substrate2and a top surface of the frame3is in a range of, for example, 2.0 mm to 10.0 mm. With such a height between the upper surface2aof the substrate2and the top surface of the frame3, the light source device can be mounted incorporated in a small electronic device, such as a smartphone.

Light Emitting Part

As shown inFIG.5, each light emitting part41includes a light emitting element42, a wavelength conversion member45covering an upper surface of the light emitting element42, and an light-reflective member46covering lateral surfaces of the light emitting element42and lateral surfaces of the wavelength conversion member45.

The light emitting element42has at least a semiconductor layered body43and electrodes44having two polarities (for example, a P-side electrode and an N-side electrode). The electrodes44are electrically connected to the connection electrodes of the substrate2. When mounting in a face-down manner, the light emitting element42desirably emits light mainly from a surface of the light emitting element42opposite to a surface of the light emitting element42provided with the electrodes44(hereinafter may be referred to as an “upper surface of the light emitting element42”).

The light-reflective member46is formed of, for example, a white resin containing a light diffusing material such as titanium oxide. With the light-reflective member46covering the lateral surfaces of the light emitting element42, the light emitted from the lateral surfaces of the light emitting element42can be reflected at the light-reflective member46, to be emitted from the upper surface of the light emitting element42. This allows for efficiently utilizing the light emitted from the light emitting element42.

The wavelength conversion member45is formed of a silicone resin containing a phosphor or the like, for example. The upper surface of the wavelength conversion member45can serve as the light emitting surface41aof the light emitting part41. With the wavelength conversion member45covering the upper surface of the light emitting element42, light in a desired wavelength range can be emitted from the light emitting surface41aof the light emitting part41.

The light emitting parts41, each having a configuration described above, can be controlled to be turned on discretely from each other. That is, the plurality of light emitting parts41can be individually turned on.

First Lens

The first lens10is provided to reduce the full-width half-maximum of light emitted from the light emitting part41so that the emitted light has the directivity toward the corresponding irradiation region. The first lens10includes a plurality of first unit lenses11, each first unit lens being provided for a respective one of the light emitting parts41. The first lens10according to the present embodiment includes twenty-five first unit lenses11, each first unit lens being provided for a respective one of the twenty-five light emitting parts41. The first unit lenses11shown inFIG.1are provided separately from each other. However, the first unit lenses11may be connected to respective adjacent first unit lenses to be formed as a single monolithic member as shown inFIG.4B. The first lens10A having a structure in which the first unit lenses11are formed as a single monolithic body can be regarded as a single lens that collectively covers the light emitting surfaces41aof the twenty-five light emitting parts41and that includes the twenty-five first unit lenses11, each first unit lens being provided for a respective one of the light emitting parts41.

For the first unit lens11in the present embodiment, a total internal reflection lens (TIR lens) is used. As used herein, the term “total internal reflection lens” refers to a lens configured to adjust the directivity of light by using total reflection inside the lens. As shown inFIG.5, the total internal reflection lens used in the present embodiment has a lower surface13in which a recess14is defined and an upper surface12having a corrugated cross-sectional shape. The total internal reflection lens is a lens having a substantially conical trapezoidal shape that is tapered from the upper surface12to the lower surface13. The total internal reflection lens used in the present embodiment has a rotationally symmetric shape about the optical axis B1.

The first unit lens11, which is the total internal reflection lens, is disposed, such that the inner surface14adefining the recess14is located above the light emitting surface41aof the light emitting part41and covers the light emitting surface41a. That is, the first unit lens11is disposed such that an opening end16of the recess14(i.e., a connection portion between the inner surface14aof the recess14and the lower surface13) is located outward of the outer periphery of the light emitting surface41ain a top view.

Next, referring toFIGS.1,2A and4A, the extending direction of the optical axis B1of the first unit lens11will be described.

As shown inFIG.2A, the first unit lenses11disposed corresponding to respective light emitting parts41arranged in a matrix with five rows and five columns are also arranged in a matrix of five rows and five columns. The optical axis B1of at least one first unit lens11is tilted with respect to the optical axis B2of the optical lens30. In the present embodiment, as shown inFIGS.1and4A, first unit lenses11other than the first unit lens (central first unit lens)20that is disposed on the central light emitting part50are disposed such that their respective optical axes B1are tilted with respect to the optical axis B2of the optical lens30, which will be described below. As used herein, the “two optical axes are tilted” refers to that two optical axes intersect each other with an angle therebetween, that is, two optical axes are not parallel to each other. Tilt angles of the optical axes B1of the first unit lenses11other than the central first unit lens20with respect to the optical axis B2of the optical lens30are appropriately set according to the arrangement relationship between each light emitting part41, where a respective first unit lens11is disposed, and a respective irradiation region that corresponds to the light emitting part41. More specifically, the tilt angle is set such that the light emitted from a first unit lens11has the directivity toward a corresponding irradiation region, compared to a case in which no first unit lens11is disposed. Thus, the tilt angles for the plurality of first unit lenses11can be set to be different values according to the arrangement relationship between each light emitting part41, where the first unit lens11is disposed, and a respective irradiation region that corresponds to the light emitting part41.

As described above, in the present embodiment, the twenty-five light emitting parts41arranged in five rows and five columns and the irradiation regions corresponding to these light emitting parts have the point-symmetric arrangement relationship with respect to the single point O located above the central light emitting part50.

(1) an optical axis of a first unit lens11disposed in the third row and the second column and an optical axis of a first unit lens11disposed in the third row and the fourth column are tilted at the same tilt angle (hereinafter referred to as a first angle) with respect to the optical axis B2of the optical lens30;

(2) an optical axis of a first unit lens11disposed in the second row and the third column and an optical axis of a first unit lens11disposed in the fourth row and the third column are tilted at the same tilt angle (hereinafter referred to as a second angle) with respect to the optical axis B2of the optical lens30;

(3) an optical axis of a first unit lens11disposed in the second row and the second column, an optical axis of a first unit lens11disposed in the second row and the fourth column, an optical axis of a first unit lens11disposed in the fourth row and the second column, and an optical axis of a first unit lens11disposed in the fourth row and the fourth column are tilted at the same tilt angle (hereinafter referred to as a third angle) with respect to the optical axis B2;

(4) an optical axis of a first unit lens11disposed in the third row and the first column and an optical axis of a first unit lens11disposed in the third row and the fifth column are tilted at the same tilt angle (hereinafter referred to as a fourth angle) with respect to the optical axis B2of the optical lens30;

(5) an optical axis of a first unit lens11disposed in the first row and the third column and an optical axis of a first unit lens11disposed in the fifth row and the third column are tilted at the same tilt angle (hereinafter referred to as a fifth angle) with respect to the optical axis B2of the optical lens30;

(6) an optical axis of a first unit lens11disposed in the second row and the first column, an optical axis of a first unit lens11disposed in the second row and the fifth column, an optical axis of a first unit lens11disposed in the fourth row and the first column, and an optical axis of a first unit lens11disposed in the fourth row and the fifth column are tilted at the same tilt angle (hereinafter referred to as a sixth angle) with respect to the optical axis B2of the optical lens30;

(7) an optical axis of a first unit lens11disposed in the first row and the second column, an optical axis of a first unit lens11disposed in the first row and the fourth column, an optical axis of a first unit lens11disposed in the fifth row and the second column, and an optical axis of a first unit lens11disposed in the fifth row and the fourth column are tilted at the same tilt angle (hereinafter referred to as a seventh angle) with respect to the optical axis B2of the optical lens30; and

(8) an optical axis of a first unit lens11in the first row and the first column, an optical axis of a first unit lens11in the first row and the fifth column, an optical axis of a first unit lens11in the fifth row and the first column, and an optical axis of a first unit lens11in the fifth row and the fifth column are tilted at the same tilt angle (hereinafter referred to as an eighth angle) with respect to the optical axis B2of the optical lens30.

Moreover, when the light emitting parts41has a square shape in a top view and light emitting surfaces41aof the light emitting parts41have the same size,

(a) the first angle and the second angle are the same;

(b) the fourth angle and the fifth angle are the same;

(c) the sixth angle and the seventh angle are the same;

(d) the third angle is set larger than each of the first angle and the second angle;

(e) each of the fourth angle and the fifth angel is set larger than each of the first angle and the second angle;

(f) each of the sixth angle and the seventh angle is set larger than each of the fourth angle and the fifth angle; and

(g) the eight angle is set larger than each of the sixth angle and the seventh angle.

Referring toFIG.20, a description will be given on a specific method of calculating an angle γ (seeFIG.4C) at which the optical axis B1of at least one first unit lens11is tilted with respect to the optical axis B2of the optical lens30when the light emitting parts41are arranged in a matrix. InFIG.20, illustration of the first unit lens11is omitted for ease of understanding of the figure.

When the light emitting parts41are arranged in a matrix, the angle γ can be calculated, for example, by Formula 1 given below, under the conditions of:

(a) L is defined as the minimum distance from the optical axis B2of the optical lens30to the center of the light emitting surface41aof the light emitting part41disposed at the corner of the matrix (0<L);

(b) x is defined as the minimum distance between the optical axis B2of the optical lens30and the center of the light emitting surface41aof a light emitting part41covered with a corresponding first unit lens11that has the optical axis B1tilted with respect to the optical axis B2(in an example shown inFIG.20, the light emitting surface41aof the light emitting part41disposed in the third row and the fourth column) (0<x≤L); and
(c) when a central point Q0is defined as an intersection of a plane in which the light emitting surfaces41aof the plurality of light emitting parts41extend and the optical axis B2of the optical lens30(in the example shown inFIG.20, the midpoint P of the light emitting surface50aof the central light emitting part50), α is defined as an angle formed by a straight line S1connecting the central point Q0and one point Q1of two points that are located at two diagonal corners of the area R1(which is an area including all of the two or more irradiation regions), and a straight line S2connecting the central point Q0and the other point Q2of the two points (0°<α<180°).

The term “light emitting part41located at a corner of the matrix” refers to one of light emitting parts located at four corners of the matrix. Thus, for example, when the light emitting parts41are arranged in the matrix of five rows and five columns, the “light emitting part41located at a corner of the matrix” can be the light emitting part41in the first row and the first column, the light emitting part41in the first row and the fifth column, the light emitting part41in the fifth row and first column, or the light emitting part41in the fifth row and the fifth column.

γ=tan-1(xL⨯tan⁡(α2))(1)
Optical Lens

As shown inFIG.4A, the optical lens30is disposed above the light emitting parts41, and collectively covers the twenty-five light emitting parts41and the first lens10. The optical lens30according to the present embodiment is composed of a plurality of lenses, specifically, a first optical lens36, a second optical lens37, and a third optical lens38, which are disposed in that order from a first lens10side. The first optical lens36, the second optical lens37, and the third optical lens38are arranged with spaces between respective adjacent lenses. Within the spaces, for example, air is present. The first optical lens36, the second optical lens37, and the third optical lens38are disposed to be supported and secured on the supporting portion5at their respective end portions, the supporting portion5being located on the inner lateral surface of the frame3. In the accompanying drawings, illustration of a supporting portion that supports the second optical lens37and a supporting portion that supports the third optical lens38are omitted. The first optical lens36, the second optical lens37, and the third optical lens38are disposed with their optical axes coinciding with each other. Thus, the optical axis B2of the optical lens30is specified as a single axis. In the present embodiment, the optical lens30is disposed such that its optical axis B2is orthogonal to the upper surface2aof the substrate2and passes through the midpoint P of the central light emitting part50. Therefore, the single point O that determines the point-symmetric arrangement relationship between the light emitting part41and the corresponding irradiation region is located on the optical axis B2of the optical lens30.

The first optical lens36, the second optical lens37, and the third optical lens38may be supported using other appropriate configuration than the supporting portion5located on the inner lateral surface of the frame3. For example, the first optical lens36, the second optical lens37, and the third optical lens38may be attached to a supporting rod provided on an inner upper surface of the frame3to be supported.

The optical lens30has a first surface31located on the light emitting surface41aside of the light emitting part41and a second surface32on the opposite side to the first surface31, i.e., located at the opening4side of the frame3. As in the present embodiment, when the optical lens30includes the first optical lens36, the second optical lens37, and the third optical lens38, a surface of the first optical lens36at a light emitting part41side is the first surface31, and a surface of the third optical lens38at an opening4side of the frame3is the second surface32.

The first surface31includes a plurality of incident regions33corresponding to respective light emitting parts41such that light emitted from each of the light emitting parts41is incident on a respective one of the light emitting parts41. The second surface32includes a plurality of emission regions34corresponding to the respective plurality of incident regions33.

As described above, distribution of light emitted from each light emitting part41depends on the shapes of the first surface31including the incident regions33and the second surface32including the emission regions34of the optical lens30. In the present embodiment, the optical lens30is composed of three lenses, namely, the first optical lens36, the second optical lens37, and the third optical lens38, which are spaced apart from each other with the air interposed therebetween. Therefore, the distribution of light between the incident region33and the emission region34can be influenced by a shape of a region of the first optical lens36(the emission region) from which light is emitted, the difference between the refractive index of the first optical lens36and the refractive index of the air, a shape of a region of the second optical lens37(the incident region) on which light is incident, a shape of a region of the second optical lens37(the emission region) from which light is emitted, the difference between the refractive index of the second optical lens37and the refractive index of the air, a shape of a region of the third optical lens38(the incident region) onto which light is incident, and the difference between the refractive index of the third optical lens38and the refractive index of the air. Thus, a shape of the incident region33and a shape of the emission region34are designed in consideration of these factors.

Incident regions33through which lights emitted from corresponding adjacent light emitting parts41enter the optical lens30may entirely or partially overlap each other, depending on the full-width half-maximum of the light emitted from corresponding first unit lenses11, the distance from the first unit lenses11to the optical lens30, the tilt angle of the optical axis B1of the corresponding first unit lens11with respect to the optical axis B2of the optical lens30, and the like. Therefore, two adjacent incident regions33of the plurality of incident regions33of the optical lens30may entirely or partially overlap. In the present specification, in the incident regions33, a region onto which only light emitted from a corresponding first unit lens11is incident is referred to as a “first incident region33c,” and a region overlapping the adjacent incident region33is referred to as a “second incident region33d.” The first incident regions33cand the second incident regions33dare shown inFIG.4C. Therefore, each incident region33of the optical lens30may include the first incident region33con which the light emitted from a light emitting part41corresponding to the incident region33is incident, and the second incident region33don which light emitted from an adjacent light emitting section41light from the one light emitting part41are incident. Thus, each incident region33may not necessarily be designed discretely, but may be designed appropriately in relation to the adjacent incident region.

Similarly, emission regions34of the optical lens30through which lights entered the optical lens30from corresponding adjacent incident regions33are emitted may entirely or partially overlap each other, depending on the position of the corresponding incident region33, the difference between the refractive index of the optical lens30and the refractive index of the medium in contact with the optical lens30, the arrangement of the corresponding incident regions, and the like. Therefore, two adjacent emission regions34of the plurality of emission regions34of the optical lens30may entirely or partially overlap. In the present specification, in the emission regions34, a region from which only light that has been emitted from a corresponding first unit lens11is emitted is referred to as a “first emission region34c,” and a region overlapping the adjacent emission region34is referred to as a second emission region34d. The first emission regions34cand the second emission regions34dare shown inFIG.4A. Therefore, each emission region34of the optical lens30may include the first emission region34cfrom which light entering the optical lens30through a corresponding incident region33is emitted, and the second emission region34dfrom which light entered the optical lens30from an adjacent incident region33and light entering through the corresponding incident region33are emitted. Thus, each emission region34may not necessarily be designed independently, but may be designed as appropriate in relation to the adjacent emission region34.

A minimum distance d0between the first surface31of the optical lens30and the first lens10, shown inFIG.4C, is, for example, 0.1 mm or more and 1.0 mm or less, and preferably 0.1 mm or more and 0.5 mm or less. The minimum distance d0in the present embodiment refers to an interval between the first surface31of the optical lens30and the first lens10which are located closest to each other, regardless of the shape of the first surface31of the optical lens30and the shape of the first lens10. With such a minimum distance d0between the first surface31of the optical lens30and the first lens10, the light source device can be mounted on a small electronic device, such as a smartphone.

Next, referring toFIGS.6A to7B, a detailed description will be given on the distribution of light emitted from each light emitting part41.

Distribution of Light Emitted from Central Light Emitting Part50

As shown inFIGS.6A and6B, the light emitted from the light emitting surface50aof the central light emitting part50at the first full-width half-maximum θ1mainly travels in sequence as follows:

(1) Light enters the central first unit lens20through an inner surface23adefining a recess23of the central first unit lens20(seeFIG.6A).

(2) Subsequently, the entered light is totally reflected by an inner lateral surface24of the central first unit lens20.

(3) Then, the reflected light is emitted from the upper surface21of the central first unit lens20at the second full-width half-maximum θ2.

(4) The emitted light enters the optical lens30through an incident region33acorresponding to the central light emitting part50(seeFIG.6B).

(5) Then, the light is emitted from an emission region34acorresponding to the incident region33atoward the outside of the optical lens30.

(6) The light emitted from the emission region34ais irradiated to the irradiation region (irradiation region located directly above the central light emitting part50) R33corresponding to the central light emitting part50.

The central first unit lens20is disposed such that its optical axis B1is orthogonal to the light emitting surface50aof the central light emitting part50so that light emitted from the central light emitting part50is irradiated to the irradiation region R33directly above the central light emitting part50. That is, the optical axis of the central first unit lens20coincides the optical axis B2of the optical lens30.

The shape of an incident region33a(an incident region of the first optical lens36) of the optical lens30that corresponds to the central light emitting part50and the shape of the emission region34a(the emission region of the third optical lens38) of the optical lens30that corresponds to the incident region33aare appropriately designed so that the irradiation region R33disposed directly above the central light emitting part50is irradiated with the light emitted from the central first unit lens20.

Likewise, the shape of the emission region of the first optical lens36that corresponds to the central light emitting part50, the shapes of the incident region and the emission region of the second optical lens37, and the shape of the incident region of the third optical lens38are appropriately designed so that the irradiation region R33disposed directly above the central light emitting part50is irradiated with the light emitted from the central first unit lens20.

Distribution of Light Emitted from Light Emitting Part Other than Central Light Emitting Part50

Distributions of lights emitted from light emitting parts other than the central light emitting part50vary according to positions of the light emitting parts, but are the same in that the light from each of these light emitting parts intersects the optical axis B2of the optical lens30and is irradiated to a corresponding irradiation region.

For this reason, distribution of light emitted the light emitting part55(a peripheral light emitting part) disposed in the first row and third column (seeFIG.2A) will be described below as an example of the distribution of light emitted from the light emitting parts other than the central light emitting part50.

As shown inFIG.7A, light emitted from a light emitting surface55aof peripheral light emitting part55at the first full-width half-maximum el mainly travels as follows.

(1) The light emitted from the light emitting surface55aenters the peripheral first unit lens25through an inner surface28aof a recess28defined in the first unit lens (peripheral first unit lens)25that is disposed to cover the light emitting surface55aof the peripheral light emitting part55(seeFIG.7A).
(2) Subsequently, the entered light is totally reflected at the inner lateral surface29of the peripheral first unit lens25.
(3) Then, the reflected light is emitted from an upper surface26of the peripheral first unit lens25at the second full-width half-maximum θ2.
(4) The emitted light enters the optical lens30through an incident region33bcorresponding to the peripheral light emitting part55(seeFIG.7B).
(5) Subsequently, the entered light intersects the optical axis B2of the optical lens30within the optical lens30.
(6) Then, the light is emitted from the emission region34bcorresponding to the incident region33bto the outside of the optical lens30.
(7) The light emitted from the emission region34bis irradiated to an irradiation region R35corresponding to the peripheral light emitting part55.

The light emitted from the peripheral light emitting part55may intersect the optical axis B2of the optical lens30at a location other than inside the optical lens30, and can intersect the optical axis B2of the optical lens30at any appropriate location between a location where the light is emitted from the peripheral light emitting part55to a location where the corresponding irradiation region R35is irradiated with the light.

As described above, in the present embodiment, the twenty-five light emitting parts41and the irradiation regions corresponding to respective light emitting parts41have the point-symmetric arrangement relationship with respect to the single point O above the central light emitting part50. Thus, the peripheral first unit lens25is disposed such that its optical axis B1intersects the optical axis B2of the optical lens30above the central light emitting part50. With this arrangement, the light emitted from the light emitting part41through the peripheral first unit lens25has higher directivity toward the corresponding irradiation region R35, compared to when the peripheral first unit lens25is not provided.

The shape of the incident region33b(the incident region of the first optical lens36) of the optical lens30that corresponds to the peripheral light emitting part55and the shape of the emission region34b(the emission region of the third optical lens38) of the optical lens30are appropriately designed so that the irradiation region R35is irradiated with the light emitted from the peripheral first unit lens25, the irradiation region R35being disposed at the point-symmetric position to the peripheral light emitting part55with respect to the single point O.

Likewise, the shape of the emission region of the first optical lens36, the shapes of the incident region and the emission region of the second optical lens37, and the shape of the incident region of the third optical lens38are appropriately designed so that the irradiation region disposed at the point-symmetric position to the peripheral first unit lens with respect to the single point O is irradiated with the light emitted from the peripheral first unit lens25.

As described above, the light source1according to the present embodiment includes the first lens10disposed to cover the light emitting surface41aof the light emitting part41, so that a full-width half-maximum of light emitted from the light emitting surface41aof each of the light emitting parts41is narrowed by the first lens10and enters the optical lens30after obtaining the high directivity towards the corresponding irradiation region. Thus, light emitted from the light emitting surface41aof each of the light emitting parts41can be efficiently irradiated to a desired corresponding irradiation region.

2. Second Embodiment

A light source201according to a second embodiment shown inFIG.8differs from the light source1according to the first embodiment in that the first unit lens is a lens having a single convex surface (convex surface) at an optical lens30side. Each of first unit lenses211according to the second embodiment has, for example, a semicircular cross-sectional shape with a convex surface211aformed by a smooth curved surface. Each first unit lens211is disposed to cover the light emitting surface41aof a corresponding light emitting part41with its lower surface211b.

Each of the first unit lens211has such a simple shape, which allows for facilitating producing a mold or die used for forming the first unit lenses211.

A light source301according to a third embodiment shown inFIG.9differs from the light source1according to the first embodiment in that the first unit lens is a frustum lens in which an area of an upper surface312is greater than an area of a lower surface313. Each of first unit lenses311according to the third embodiment has the upper surface312and the lower surface313each of which has, for example, a circular shape, a triangular shape, a rectangular shape, etc. Each first unit lens311is disposed to cover the light emitting surface41aof a corresponding light emitting part41with the lower surface313. Each first unit lens311may be a lens other than a frustum lens in which the area of the upper surface312is greater than the area of the lower surface313, and may be a frustum lens in which the area of the upper surface312is smaller than the area of the lower surface313, or may be a columnar lens in which the area of the upper surface312is equal to the area of the lower surface313. Such a first unit lens311can also adjust the directivity of light utilizing the reflection inside the first unit lens311, like the total internal reflection lens described above.

Each of the first unit lenses311have such a simple shape, which facilitates producing a mold or die used for forming the first unit lens311.

A light source of each of the present embodiment and fifth and sixth embodiments to be described below differs from the light source1according to the first embodiment in that the first lens is a lens collectively covering the light emitting surfaces41aof the plurality of light emitting parts41and having at least a single convex surface (convex surface) at the optical lens30side.

A first lens410of a light source401according to the present embodiment has a single convex surface (convex surface)410aat the optical lens30side. As shown inFIG.10, in the first lens410, the convex surface410ahas an arc outline on the cross section and is formed by a smooth curved surface. The first lens410is disposed to collectively cover the light emitting surfaces41aof all the light emitting parts41with its lower surface410b.

The first lens410has such a simple shape, which allows for facilitating producing a mold or die used for forming the first lens410. Also, with the first lens410having such a structure, lenses corresponding to respective light emitting parts41in arrangement adjusted for respective light emitting parts41(such as the first unit lenses11in the first embodiment) is not required. For example, it is sufficient to align an optical axis B4of the first lens410with the optical axis B2of the optical lens30, which can simplify the manufacturing process.

The curvature of the convex surface410aof the first lens410may be constant from the optical axis B4to an end portion of the first lens410, or may vary according to the distance from the optical axis B4. In particular, with the curvature of the convex surface410aof the first lens410increased from the optical axis B4to the end portion of the first lens410, the following effects can be expected.

Among lights emitted from the light emitting parts41disposed near the end of the convex surface410aof the first lens410(for example, in the present embodiment, the light emitting parts41disposed in the first row and the k-th column, in the fifth row and the k-th column, in the k-th row and the first column, and in the k-th row and the fifth column (k=1 to 5)), light that deviates from the direction of a desired directivity (in the present embodiment, the direction toward the irradiation region corresponding to the light emitting part41), in particular, light traveling toward the frame3is unlikely to be incident on the optical lens30. Consequently, the loss of light in this light emitting part41may be increased. For this reason, with the curvature of the end portion of the convex surface410aof the first lens410greater than the curvature of the central portion of the convex surface410a, among the lights emitted from the light emitting parts41disposed near the end portion of the convex surface410a, the light traveling toward the frame3can be refracted in the direction of the desired directivity. This allows for reducing the loss of light of such a light emitting part41.

A first lens510of a light source501according to the present embodiment has a single convex surface (convex surface)510aon the optical lens30side. As shown inFIG.11, in the first lens510, the convex surface510aincludes a flat surface510blocated in a central portion of the convex surface510a, and curved surfaces510c, each connecting the flat surface510band a lower surface510dof the first lens510and being located at the end of the first lens510.

The flat surface510bis orthogonal to the optical axis B2of the optical lens30. Each of the curved surfaces510cis curved toward the outside of the first lens510. The first lens510is disposed with the lower surface510dcollectively covering the upper surfaces41aof all the light emitting parts41.

As described above about the light source401of the fourth embodiment, also in the light source501according to the present embodiment, increasing the curvature of the end portion side of the first lens510in the curved surfaces510cof the first lens510allows light emitted from the light emitting part41disposed near the end portion of the first lens510to be refracted in the direction of the desired directivity (in the present embodiment, in the direction toward the irradiation region corresponding to the above-mentioned light emitting part41). Therefore, the loss of light in this light emitting part41can be reduced. Furthermore, with the flat surface at the center portion of the convex surface510aof the first lens510, a thickness of the first lens510can be smaller than a first lens having a single convex curved surface across the entirety of the optical lens30side of the first lens, such as the light source401according to the fourth embodiment, so that the size of the light source reduced.

A first lens610of a light source601according to the present embodiment has a single convex surface (convex surface)610aat the optical lens30side.

As shown inFIG.12, the convex surface610ais a smoothly curved surface that has a cross section formed in an annular shape with respect to the optical axis B6of the first lens610centered. Therefore, in the cross-sectional shape of the first lens610, the convex surface610ahas two apex portions610d. Each apex portion610dof the convex surface610ais desirably located at a position where a distance d1between the apex portion610dof the convex surface610aand the optical axis B6of the first lens610is shorter than a distance d2between the apex portion610dof the convex surface610aand an outer circumferential end610fof the first lens610.

The center of the first lens610is formed in a concave surface610ccontinuous to the convex surface610a, and an apex portion610eof the concave surface610cis disposed on the optical axis B6of the first lens610. The optical axis B6of the first lens610is disposed to coincide with the optical axis B2of the optical lens30.

An end portion of the first lens610(in the present embodiment, an end portion of the convex surface610ain the vicinity of the outer circumferential end610f) preferably has a curvature greater than the curvature of the concave surface610c.

The first lens610is disposed with a lower surface610bcollectively covering the upper surfaces41aof all the light emitting parts41.

As shown inFIG.13, a light source according to a seventh embodiment differs from the light source1according to the first embodiment in that the first unit lens other than the central first unit lens is the total internal reflection lens of a rotationally asymmetric shape with respect to an optical axis of the central first unit lens. A first unit lens711other than the central first unit lens according to the seventh embodiment is the total internal reflection lens with a rotationally asymmetric shape with respect to an optical axis B7, in which a connection portion716(an opening end of a recess714), which connects a lower surface713and an inner surface714athat defines the recess714in the lower surface713, is formed to surround the light emitting surface41aand to contact the upper surface41bof the light emitting part41. Such a first unit lens711is disposed such that the inner surface714adefining the recess714at the light emitting surface41aside covers the light emitting surface41aof the light emitting part41. Therefore, as indicated by the arrow Y inFIG.13, almost all the lights emitted from the light emitting surfaces41aof the light emitting parts41enter corresponding ones of first unit lenses711through the inner surfaces714aof corresponding ones of the recesses714of the first unit lenses711. This allows for increasing the efficiency of usage of the light emitted from the light emitting part41.

The tilt angle of the first unit lens711with respect to the optical axis of the optical lens varies according to corresponding light emitting part in a matrix of five rows and five columns. Thus, the shape of the first unit lens711differs according to each light emitting part41.

In the present embodiment, the twenty-five light emitting parts41and the irradiation regions corresponding to the respective light emitting parts41have the point-symmetric arrangement relationship with respect to the single point O above the central light emitting part50. Therefore, the first unit lenses711have respective shapes as described below.

(1) The first unit lens711disposed in the third row and the second column and the first unit lens711disposed in the third row and the fourth column have the same shape (shape 1).

(2) The first unit lens711disposed in the second row and the third column and the first unit lens711disposed in the fourth row and the third column have the same shape (shape 2).

(3-1) The first unit lens711disposed in the second row and the second column and the first unit lens711disposed in the fourth row and the fourth column have the same shape (shape 3-1).

(3-2) The first unit lens711disposed in the second row and the fourth column and the first unit lens711disposed in the fourth row and the second column have the same shape (shape 3-2).

(4) The first unit lens711disposed in the third row and the first column and the first unit lens711disposed in the third row and the fifth column have the same shape (shape 4).

(5) The first unit lens711disposed in the first row and the third column and the first unit lens711disposed in the fifth row and the third column have the same shape (shape 5).

(6-1) The first unit lens711disposed in the second row and the first column and the first unit lens711disposed in the fourth row and the fifth column have the same shape (shape 6-1).

(6-2) The first unit lens711disposed in the second row and the fifth column and the first unit lens711disposed in the fourth row and the first column have the same shape (shape 6-2).

(7-1) The first unit lens711disposed in the first row and the second column and the first unit lens711disposed in the fifth row and the fourth column have the same shape (shape 7-1).

(7-2) The first unit lens711disposed in the first row and the fourth column and the first unit lens711disposed in the fifth row and the second column have the same shape (shape 7-2).

(8-1) The first unit lens711disposed in the first row and the first column and the first unit lens711disposed in the fifth row and the fifth column have the same shape (shape 8-1).

(8-2) The first unit lens711disposed in the first row and the fifth column and the first unit lens711disposed in the fifth row and the first column have the same shape (shape 8-2).

Furthermore, when the light emitting parts41have a square shape in a top view and have respective light emitting surfaces41aof the same dimensions, the shape 1 and the shape 2 are the same, the shape 4 and the shape 5 are the same, the shape 6-1, the shape 6-2, the shape 7-1, and the shape 7-2 are the same, the shape 3-1 and the shape 3-2 are the same shape, and the shape 8-1 and the shape 8-2 are the same.

A light source801according to an eighth embodiment shown inFIG.14differs from the light source1according to the first embodiment in that the wavelength conversion member disposed in the light emitting part covers an upper surface of the light emitting element42and an upper surface of the light-reflective member46. A wavelength conversion member845according to the eighth embodiment may be disposed such that a plurality of wavelength conversion members845are provided for respective light emitting parts41, or such that a single wavelength conversion member845collectively covers the upper surfaces of the semiconductor layered bodies43and the upper surfaces of the light-reflective members46of all twenty-five light emitting parts41.

The wavelength conversion member845is a thin member, and accordingly, when the wavelength conversion member845is disposed to cover the upper surface of the light emitting element42and the upper surface of the light-reflective member46, a light emitting surface841aof a light emitting part841can be regarded as a region of the wavelength conversion member845located directly above the upper surface of the light emitting element42.

VARIANT EXAMPLES

While the optical lens30is composed of three lenses, namely, the first optical lens36, the second optical lens37, and the third optical lens38in the light sources according to the above-mentioned first to eighth embodiments, the optical lens may be composed of other number of lens or lenses. For example, as shown inFIG.15, an optical lens930may be composed of a single lens. For example, as shown inFIG.16, an optical lens1030may be composed of two lenses, namely, a first optical lens1036and a second optical lens1037. For example, an optical lens may be composed of four or more lenses.

While the optical lens is supported using the supporting portion5located on the inner surface of the frame3the light sources according to the first to eighth embodiments and a variant example described above, the optical lens may be supported using other appropriate configuration. For example, as shown inFIG.17, optical lenses36,37, and38may be supported by a first leg6A, a second leg6B, and a third leg6C connected to the ends of the first optical lens36, the second optical lens37, and the third optical lens38, respectively.

The first leg6A extends from the end of the first optical lens36to the upper surface2aof the substrate2to support the first optical lens36. The second leg6B extends from the end of the second optical lens37to the upper surface of the first leg6A to support the second optical lens37. The third leg6C extends from the end of the third optical lens38to the upper surface of the second leg6B to support the third optical lens38.

The first leg6A, the second leg6B, and the third leg6C may be formed of, for example, a light-reflective member or a light shielding member. The first leg6A, the second leg6B, and the third leg6C may be portions of lenses formed of the same material as the first optical lens36, the second optical lens37, and the third optical lens38, respectively. In this case, a joint member7joining adjacent ones of the first to third legs6A,6B, and6C may be formed of, for example, an adhesive or the like.

The first leg6A, the second leg6B, and the third leg6C may be composed of a single monolithic member.

In a case in which each optical lens is supported by a leg connected to the end of each optical lens in this way, the light source may not include a frame.

EXAMPLES

Examples will be described below.

In Examples, simulation of illuminance distribution in the irradiation region was conducted using a light source model based on the light source for a flash according to the first embodiment. The light source model included a substrate, twenty-five light emitting parts configured to be individually turned on, a first lens including twenty-five first unit lenses corresponding to respective light emitting parts, an optical lens disposed above the first lens, and a frame accommodating the light emitting parts, the first lens, and the optical lens, and having an opening in an upper surface of the frame.

The twenty-five light emitting parts were set to be arranged in a matrix of five rows and five columns with their adjacent lateral surfaces being in contact with each other. Each light emitting part was set to have a square shape in the top view with each side of 1.13 mm. The light emitting surface of each light emitting part was set to have a square shape with each side of 0.24 mm.

The irradiated regions were set to be arranged in a matrix of five rows and five columns each corresponding to a respective one of twenty-five light emitting parts. Each irradiation region was set to be a rectangular plane with a short side of 280 mm and a long side of 370 mm with reference to an angle of view and the aspect ratio of a camera, and the twenty-five irradiation regions are assumed to be arranged adjacent to each other in the same plane.

The distance between the midpoint of the irradiation region in the third row and the third column and the midpoint of the central light emitting part in the third row and the third column was set at 30 cm.

The optical lens was a lens composed of three lenses, namely, the first optical lens, the second optical lens, and the third optical lens. The refractive index of each of the first optical lens, the second optical lens, and the third optical lens was set at 1.58. The optical lens was set to be oriented such that an optical axis of the optical lens was orthogonal to the light emitting surface of the central light emitting part.

First unit lenses disposed were also arranged in a matrix of five rows and five columns corresponding to the light emitting parts. The refractive index of the first unit lens was set at 1.58.

The central first unit lens disposed in the third row and the third column was set to be oriented such that an optical axis of the central first unit lens coincided the optical axis of the optical lens.

The first unit lens disposed in the second row and the third column, the first unit lens disposed in the third row and the second column, the first unit lens disposed in the third row and the fourth column, and the first unit lens disposed in the fourth row and the second column were set such that their respective optical axes were tilted by 15° with respect to the optical axis of the optical lens. That is, the first angle and the second angle were set at 15°.

The first unit lens disposed in the second row and the second column, the first unit lens disposed in the second row and the fourth column, the first unit lens disposed in the fourth row and the second column, and the first unit lens disposed in the fourth row and the fourth column were set such that their respective optical axes were tilted by 22° with respect to the optical axis of the optical lens. That is, the third angle were set at 22°.

The first unit lens disposed in the first row and the third column, the first unit lens disposed in the third row and the first column, the first unit lens disposed in the third row and the fifth column, and the first unit lens disposed in the fifth row and the third column were set such that their respective optical axes were tilted by 27° with respect to the optical axis of the optical lens. That is, the fourth angle and the fifth angle were set at 27°.

The first unit lens disposed in the first row and the second column, the first unit lens disposed in the first row and the fourth column, the first unit lens disposed in the second row and the first column, the first unit lens disposed in the second row and the fifth column, the first unit lens disposed in the fourth row and the first column, the first unit lens disposed in the fourth row and the fifth column, the first unit lens disposed in the fifth row and the second column, and the first unit lens disposed in the fifth row and the fourth column were set such that their respective optical axes were tilted by 30.5° with respect to the optical axis of the optical lens. That is, the sixth angle and the seventh angle were set at 30°.

The first unit lens in the first row and the first column, the first unit lens in the first row and the fifth column, the first unit lens in the fifth row and the first column, and the first unit lens in the fifth row and the fifth column were set such that their respective optical axes were tilted by 35° with respect to the optical axis of the optical lens. That is, the eighth angle was set at 35°.

The air was set to be disposed in a space in contact with the first unit lens and the optical lens. The refractive index of the air was set at 1.

In consideration of the settings described above, the shapes of the first and second surfaces of the optical lens and the shape of the first unit lens were set appropriately to irradiate at least one irradiation region with light emitted from corresponding at least one light emitting part.

In the light source model of Examples having a configuration as described above, the light emitting part in the third row and the first column was turned on, and the illuminance distribution in the corresponding irradiation region was confirmed. The simulation result is shown inFIG.18. In Examples, the ratio of the amount of light with which the irradiation region was irradiated to the amount of light emitted from the light emitting part (the efficiency of usage of the light) was 24%.

COMPARATIVE EXAMPLE

Next, Comparative Example will be described.

A light source model of Comparative Example had the same configuration as the light source according to Example with the same setting conditions for members described above, except that the first lens is not provided.

In the light source model of Comparative Example, the light emitting part in the third row and the first column was turned on, and the illuminance distribution in the corresponding irradiation region was confirmed. The simulation result is shown inFIG.19. In Comparative Example, the ratio of the amount of light with which the irradiation region was irradiated to the amount of light emitted from the light emitting part (the efficiency of usage of the light) was 6.0%.

From the simulation results described above, it can be understood that the light source model of Examples enables irradiation of the desired region with a sufficient amount of light, compared to the light source model of Comparative Example.

While certain embodiments, variant examples, and Examples of the present disclosure have been described above, the contents of the disclosure may be modified regarding the details of components, and combinations of elements, changes in order, and the like in the embodiments, variant examples, and Examples may be realized without departing from the scope and idea of the present invention.

The light source device according to certain embodiments of the present invention can irradiate light to desired irradiation region, and thus can be preferably used for lights, camera flashes, car headlights, etc. It is noted that the applications of the light source device of the present invention are not limited thereto.