Light source

Abstract

To provide a light source of which the power consumption can be reduced.SOLUTION: A light source comprises: a first light-emitting section including one or more first light-emitting elements which are connected in series; a second light-emitting section including a plurality of second light-emitting elements connected in series and more than the number of first light-emitting elements; a power source which supplies power to the first light-emitting elements and the second light-emitting elements; and a control section which turns on the first light-emitting elements and the second light-emitting elements with predetermined brightness. The first light-emitting section and the second light-emitting section are connected in parallel to the power source, a first light-emission peak wavelength of the first light-emitting elements and a second light-emission peak wavelength of the second light-emitting elements are different, a second forward voltage of the second light-emitting elements is lower than a first forward voltage of the first light-emitting elements, and an absolute value of a difference between a first voltage which is a forward voltage in the first light-emitting section and a second voltage which is a forward voltage in the second light-emitting section is lower than the second forward voltage of the second light-emitting elements.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to light sources. [Background technology]

[0002] For example, Patent Document 1 discloses an LED module having a plurality of LED chips that emit light of different colors. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-026510 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present disclosure is to provide a light source that can reduce power consumption. [Means for solving the problem]

[0005] According to one aspect of the present disclosure, a light source includes a substrate, a first light-emitting section disposed on the substrate and having one or more first light-emitting elements connected in series, a second light-emitting section disposed on the substrate and having a plurality of second light-emitting elements connected in series, the number of second light-emitting elements being greater than the number of the first light-emitting elements, a power source that supplies power to the first light-emitting element and the second light-emitting element, and a control section that lights up the first light-emitting element and the second light-emitting element at a predetermined brightness, wherein the first light-emitting section and the second light-emitting section are connected in parallel to the power source, a first emission peak wavelength of the first light-emitting element and a second emission peak wavelength of the second light-emitting element are different, a second forward voltage of the second light-emitting element is lower than the first forward voltage of the first light-emitting element, and an absolute value of the difference between a first voltage that is the forward voltage at the first light-emitting section and a second voltage that is the forward voltage at the second light-emitting section is lower than the second forward voltage of the second light-emitting element. [Effects of the Invention]

[0006] According to the present disclosure, a light source capable of reducing power consumption can be provided. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is an equivalent circuit diagram showing the configuration of a light source according to the embodiment. [Figure 2] 10 is a graph showing the relationship between a second duty ratio Duty2 and a second forward voltage Vf2 of a second light-emitting element according to the embodiment. [Figure 3] 10 is a graph showing the relationship between a second pulse forward current Ifp2 and a second forward voltage Vf2 of a second light emitting element according to the embodiment. [Figure 4] FIG. 2 is a schematic cross-sectional view of a light source according to the embodiment. [Figure 5] 1 is a schematic perspective view of a light emitting device according to an embodiment. [Figure 6] 1 is a schematic perspective view of a light emitting device according to an embodiment. [Figure 7] 1A to 1C are schematic diagrams of a light emitting device according to an embodiment, taken from multiple viewpoints. [Figure 8] FIG. 8 is a schematic cross-sectional view taken along line VIII-VIII in FIG. 7. [Figure 9] FIG. 8 is a schematic cross-sectional view taken along line IX-IX in FIG. 7. [Figure 10] FIG. 8 is a schematic cross-sectional view taken along line XX in FIG. 7. [Figure 11] FIG. 10 is a schematic front view of a light emitting device according to a modified example of the embodiment. [Figure 12] FIG. 10 is a schematic perspective view of a light emitting device according to a modified example of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, light sources according to embodiments will be described with reference to the drawings. The dimensions, materials, shapes, relative arrangements, and the like of components described in the embodiments are not intended to be limiting unless otherwise specified, and are merely illustrative examples. The sizes and positional relationships of components shown in the drawings may be exaggerated for clarity. In the following description, the same names and symbols indicate identical or similar components, and detailed descriptions will be omitted as appropriate. Cross-sectional views may also be shown as end views showing only the cut surface.

[0009] In the following description, terms indicating specific directions or positions (for example, "upper," "lower," and other terms including these terms) may be used. However, these terms are used merely to facilitate understanding of relative directions or positions in the referenced drawings. As long as the relationship of relative directions or positions indicated by terms such as "upper," "lower," etc. in the referenced drawings is the same, drawings other than those of the present disclosure, actual products, etc. may not be arranged in the same manner as in the referenced drawings.

[0010] In the figures shown below, directions may be indicated by the mutually orthogonal X-axis, Y-axis, and Z-axis. For example, in this specification, the direction along the X-axis is referred to as the first direction X, the direction along the Y-axis is referred to as the second direction Y, and the direction along the Z-axis is referred to as the third direction Z. Furthermore, the positive direction of the X-axis is referred to as the relative +X side, and the negative direction of the X-axis is referred to as the relative -X side. The positive direction of the Y-axis is referred to as the relative upward direction, and the negative direction is referred to as the relative downward direction.

[0011] [light source] FIG. 1 is an equivalent circuit diagram showing the configuration of a light source 1 according to the embodiment.

[0012] The light source 1 according to the embodiment includes a first light-emitting unit 10, a second light-emitting unit 20, a power source 30, and a control unit 40. The light source 1 also includes a substrate 200 shown in FIG.

[0013] The first light-emitting unit 10 has one or more first light-emitting elements 11 connected in series. In this specification, when the first light-emitting unit 10 includes only one light-emitting element 11, the first light-emitting unit 10 is said to have one first light-emitting element 11 connected in series. The second light-emitting unit 20 has a plurality of second light-emitting elements 21 connected in series, the number of which is greater than the number of first light-emitting elements 11. The first light-emitting unit 10 and the second light-emitting unit 20 are connected in parallel to the power source 30. In the example shown in FIG. 1 , a plurality of first light-emitting units 10 and a plurality of second light-emitting units 20 are connected in parallel to the power source 30. One first light-emitting unit 10 and a plurality of second light-emitting units 20 may also be connected in parallel to the power source 30. A plurality of first light-emitting units 10 and one second light-emitting unit 20 may also be connected in parallel to the power source 30. One first light-emitting unit 10 and one second light-emitting unit 20 may also be connected in parallel to the power source 30. In the light source 1, the first light-emitting section 10 and the second light-emitting section 20 may be connected in parallel to each other, and the light source 1 may not include the power supply 30.

[0014] The power supply 30 supplies power to the first light-emitting element 11 of the first light-emitting unit 10 and the second light-emitting element 21 of the second light-emitting unit 20. The first light-emitting element 11 and the second light-emitting element 21 are, for example, LEDs (Light Emitting Diodes) that emit light using current supplied from the power supply 30. The power supply 30 is connected between a first wiring 51 and a second wiring 52. Power from the power supply 30 is supplied to the first light-emitting element 11 and the second light-emitting element 21 through the first wiring 51. The forward direction of each of the first light-emitting element 11 and the second light-emitting element 21 is the direction from the first wiring 51 to the second wiring 52. When the first light-emitting element 11 and the second light-emitting element 21 are caused to emit light, the potential of the first wiring 51 is higher than the potential of the second wiring 52.

[0015] The power supply 30 includes, for example, a battery 31 and a boost circuit 32 that boosts the voltage of the battery 31. Note that the light source 1 is not limited to being battery-powered, and the power supply 30 does not necessarily have to include the battery 31.

[0016] The control unit 40 lights up the first light-emitting element 11 and the second light-emitting element 21 at a predetermined brightness. Lighting up at a predetermined brightness means controlling the integrated current values ​​of the first light-emitting element 11 and the second light-emitting element 21 to be the predetermined integrated current values.

[0017] The control unit 40 includes, for example, a switch unit and a current value control unit. The switch unit turns on and off the connection between the first light-emitting unit 10 and the second light-emitting unit 20 and the second wiring 52. By controlling the on and off of this switch unit, a pulse current can be supplied to each of the first light-emitting element 11 and the second light-emitting element 21. The current value control unit controls, for example, the peak value (amplitude) of the pulse current supplied to each of the first light-emitting element 11 and the second light-emitting element 21.

[0018] The control unit 40 controls, for example, a first duty ratio Duty1 of the first light-emitting element 11 and a second duty ratio Duty2 of the second light-emitting element 21 using a switch unit. The duty ratio is the ratio of the on-time to the on-off cycle of the current or voltage supplied to each of the first light-emitting element 11 and the second light-emitting element 21. Note that there may also be cases where the duty ratio is 1 (lighting control by continuous current or voltage).

[0019] For example, during a predetermined period in which the first light-emitting element 11 should be turned on, a pulse current is supplied to the first light-emitting element 11, and the first light-emitting element 11 repeatedly emits and does not emit light at a predetermined cycle. By shortening this cycle, the first light-emitting element 11 appears to be continuously lit to the human eye. Alternatively, the first light-emitting element 11 may be lit by supplying a continuous current (DC current) to the first light-emitting element 11 during the predetermined period in which the first light-emitting element 11 should be lit. Similarly, the second light-emitting element 21 may be lit by a pulse current or a continuous current during the predetermined period in which the second light-emitting element 21 should be lit.

[0020] In the example shown in Figure 1, a common control unit 40 is connected to the first light-emitting unit 10 and the second light-emitting unit 20, but the control unit connected to the first light-emitting unit 10 and the control unit connected to the second light-emitting unit 20 may be separate control units.

[0021] The first emission peak wavelength of the first light-emitting element 11 is different from the second emission peak wavelength of the second light-emitting element 21. The first emission peak wavelength of the first light-emitting element 11 is, for example, in the range of 430 nm or more and less than 490 nm, and the first light-emitting element 11 mainly emits blue light. The emission peak wavelength of the second light-emitting element 21 is, for example, in the range of 490 nm or more and less than 570 nm, and the second light-emitting element 21 mainly emits green light.

[0022] The second forward voltage Vf2 of the second light-emitting element 21 is lower than the first forward voltage Vf1 of the first light-emitting element 11. By driving the first light-emitting element 11 and the second light-emitting element 21, which have different forward voltages, with a common power supply 30, it is possible to provide a light source 1 that is smaller and less expensive than when the first light-emitting element 11 and the second light-emitting element 21 are driven by separate power supplies.

[0023] The first voltage V1, which is the forward voltage in the first light-emitting section 10, is different from the second voltage V2, which is the forward voltage in the second light-emitting section 20. The first voltage V1 is the product of the first forward voltage Vf1 of the first light-emitting element 11 and the number of first light-emitting elements 11 connected in series in the first light-emitting section 10 (which may be 1). The second voltage V2 is the product of the second forward voltage Vf2 of the second light-emitting element 21 and the number of second light-emitting elements 21 connected in series in the second light-emitting section 20.

[0024] According to the present embodiment, the number of series-connected second light-emitting elements 21 in the second light-emitting unit 20, which has second light-emitting elements 21 with a second forward voltage Vf2 lower than the first forward voltage Vf1 of the first light-emitting element 11, is made larger than the number of series-connected first light-emitting elements 11 in the first light-emitting unit 10. This makes it possible to reduce the difference between the first voltage V1 of the first light-emitting unit 10 and the second voltage V2 of the second light-emitting unit 20 compared to when the number of series-connected second light-emitting elements 21 and the number of series-connected first light-emitting elements 11 are the same. The absolute value of the difference between the first voltage V1 of the first light-emitting unit 10 and the second voltage V2 of the second light-emitting unit 20 is lower than the second forward voltage Vf2 of the second light-emitting element 21. This reduces the loss of power from the power source 30 due to the difference between the first voltage V1 of the first light-emitting unit 10 and the second voltage V2 of the second light-emitting unit 20, thereby reducing the power consumption of the light source 1. For example, if the first voltage V1 of the first light-emitting unit 10 is higher than the second voltage V2 of the second light-emitting unit 20, the power supply 30 is set to a voltage equal to or higher than the first voltage V1, which is the voltage required to light the first light-emitting unit 10. Therefore, the set voltage of the power supply 30 is higher than the second voltage V2, which is the voltage required to light the second light-emitting unit 20, which can easily result in power loss due to the difference between the set voltage of the power supply 30 and the second voltage V2 of the second light-emitting unit 20. By reducing the difference between the first voltage V1 of the first light-emitting unit 10 and the second voltage V2 of the second light-emitting unit 20 as in this embodiment, the difference between the set voltage of the power supply 30 and the second voltage V2 of the second light-emitting unit 20 can be reduced, thereby reducing the power consumption of the light source 1. For example, the absolute value of the difference between the first voltage V1 of the first light-emitting unit 10 and the second voltage V2 of the second light-emitting unit 20 is preferably 2 V or less.

[0025] <First Comparative Example> The light source of the first comparative example has eight first light-emitting units 10 and eight second light-emitting units 20 connected in parallel to a power source 30. The number of directly connected first light-emitting elements 11 in each first light-emitting unit 10 and the number of directly connected second light-emitting elements 21 in each second light-emitting unit 20 are the same, 14. Therefore, the light source has a total of 112 first light-emitting elements 11 and a total of 112 second light-emitting elements 21.

[0026] In the first comparative example, the first forward voltage Vf1 of the first light-emitting element 11 is 2.74 V, the second forward voltage Vf2 of the second light-emitting element 21 is 2.31 V, the first voltage V1 of the first light-emitting section 10 is 38.36 V, and the second voltage V2 of the second light-emitting section 20 is 32.34 V. Therefore, the absolute value of the difference between the first voltage V1 and the second voltage V2 is 6.02 V.

[0027] <First Example> The light source of the first embodiment has the same total number of first light-emitting elements 11 (112), total number of second light-emitting elements 21 (112), number of first light-emitting sections 10 connected in parallel to the power source 30 (8), number of first light-emitting sections 11 connected directly in each first light-emitting section 10 (14), first forward voltage Vf1 (2.74V) of the first light-emitting elements 11, second forward voltage Vf2 (2.31V) of the second light-emitting elements 21, and first voltage V1 (38.36V) of the first light-emitting sections 10 as the first comparative example.

[0028] In the first embodiment, the number of directly connected second light-emitting elements 21 in each second light-emitting unit 20 is 16, which is more than the number (14) of directly connected first light-emitting elements 11 in each first light-emitting unit 10. Furthermore, the number of parallel connections of the second light-emitting units 20 to the power supply 30 is 7. In the first embodiment, the second voltage V2 of the second light-emitting unit 20 is 36.96 V (= 2.31 × 16). Therefore, the absolute value of the difference between the first voltage V1 and the second voltage V2 in the first embodiment can be set to 1.4 V, which is smaller than the absolute value (6.02 V) of the difference between the first voltage V1 and the second voltage V2 in the first comparative example. As a result, the light source of the first embodiment can consume less power than the light source of the first comparative example.

[0029] <Second Comparative Example> The light source of the second comparative example has six first light-emitting units 10 and six second light-emitting units 20 connected in parallel to a power source 30. The number of directly connected first light-emitting elements 11 in each first light-emitting unit 10 and the number of directly connected second light-emitting elements 21 in each second light-emitting unit 20 are the same, 15. Therefore, the light source has a total of 90 first light-emitting elements 11 and a total of 90 second light-emitting elements 21.

[0030] In the second comparative example, the first forward voltage Vf1 of the first light-emitting element 11 is 2.79 V, the second forward voltage Vf2 of the second light-emitting element 21 is 2.41 V, the first voltage V1 of the first light-emitting section 10 is 41.85 V, and the second voltage V2 of the second light-emitting section 20 is 36.15 V. Therefore, the absolute value of the difference between the first voltage V1 and the second voltage V2 is 5.70 V.

[0031] <Second Example> The light source of the second embodiment has the same total number of first light-emitting elements 11 (90), total number of second light-emitting elements 21 (90), number of first light-emitting sections 10 connected in parallel to the power source 30 (15), number of first light-emitting sections 11 connected in direct connection in each first light-emitting section 10 (15), first forward voltage Vf1 (2.79V) of the first light-emitting elements 11, second forward voltage Vf2 (2.41V) of the second light-emitting elements 21, and first voltage V1 (41.85V) of the first light-emitting sections 10 as the second comparative example.

[0032] In the second embodiment, the number of directly connected second light-emitting elements 21 in each second light-emitting unit 20 is 18, which is more than the number (15) of directly connected first light-emitting elements 11 in each first light-emitting unit 10. Furthermore, the number of parallel connections of the second light-emitting units 20 to the power supply 30 is 5. In the second embodiment, the second voltage V2 of the second light-emitting unit 20 is 43.38 V (= 2.41 × 18). Therefore, the absolute value of the difference between the first voltage V1 and the second voltage V2 in the second embodiment can be set to 1.53 V, which is smaller than the absolute value (5.70 V) of the difference between the first voltage V1 and the second voltage V2 in the second comparative example. As a result, the light source of the second embodiment can consume less power than the light source of the second comparative example.

[0033] It should be noted that the light source of this embodiment is not limited to the various voltage values, the number of light emitting elements, the number of series connections, and the number of parallel connections shown in the first and second examples.

[0034] 2 is a graph of measurement data showing the relationship between the second duty ratio Duty2 and the second forward voltage Vf2 of the second light-emitting element 21 at a predetermined integrated current value. As the second duty ratio Duty2 decreases, the second forward voltage Vf2 increases. Similarly, for the first light-emitting element 11, as the first duty ratio Duty1 decreases, the first forward voltage Vf1 increases.

[0035] Therefore, when the second voltage V2 of the second light-emitting unit 20 is lower than the first voltage V1 of the first light-emitting unit 10 (for example, in the first embodiment described above), it is preferable that the control unit 40 controls the first duty ratio Duty1 and the second duty ratio Duty2 so that the second duty ratio Duty2 of the second light-emitting element 21 is lower than the first duty ratio Duty1 of the first light-emitting element 11. This makes it possible to increase the second voltage V2 of the second light-emitting unit 20 so as to reduce the absolute value of the difference between the first voltage V1 and the second voltage V2, thereby reducing the power consumption of the light source.

[0036] Conversely, when the second voltage V1 of the first light-emitting unit 10 is lower than the second voltage V2 of the second light-emitting unit 20 (for example, in the second embodiment described above), it is preferable that the control unit 40 controls the first duty ratio Duty1 and the second duty ratio Duty2 so that the first duty ratio Duty1 of the first light-emitting element 11 is lower than the second duty ratio Duty2 of the second light-emitting element 21. This makes it possible to increase the first voltage V1 of the first light-emitting unit 10 so as to reduce the absolute value of the difference between the first voltage V1 and the second voltage V2, thereby reducing the power consumption of the light source.

[0037] The control unit 40 controls each of the first light-emitting element 11 and the second light-emitting element 21 to achieve a predetermined brightness, in other words, a predetermined integrated current value. To achieve the predetermined integrated current value (to prevent the integrated current value from changing from the predetermined value), the control unit 40 increases the pulse forward current (pulse amplitude or peak current value) Ifp when the duty ratio (ratio of on-time to cycle) decreases. When the pulse forward current Ifp increases, the temperature of the light-emitting element rises, making the light-emitting element more susceptible to failure.

[0038] 3 is a graph of measurement data showing the relationship between the second pulse forward current Ifp2 and the second forward voltage Vf2 of the second light-emitting element 21 at a predetermined integrated current value. As the second forward voltage Vf2 increases, the second pulse forward current Ifp2 increases. Also, as described above with reference to FIG. 2, as the second duty ratio Duty2 decreases, the second forward voltage Vf2 increases. Therefore, as the second duty ratio Duty2 decreases, the second pulse forward current Ifp2 increases. Similarly, for the first light-emitting element 11, as the first duty ratio Duty1 decreases, the first pulse forward current Ifp1 increases.

[0039] When the second voltage V2 of the second light-emitting unit 20 is lower than the second voltage V1 of the first light-emitting unit 10 and the second duty ratio Duty2 of the second light-emitting element 21 is lower than the first duty ratio Duty1 of the first light-emitting element 11, the second pulse forward current Ifp2 of the second light-emitting element 21 is likely to be high. In this case, it is preferable that the second integrated current value of the second light-emitting element 21 is lower than the first integrated current value of the first light-emitting element 11. This prevents the second pulse forward current Ifp2 of the second light-emitting element 21 from becoming too high, reduces a temperature rise in the second light-emitting element 21, and makes the second light-emitting element 21 less likely to break down.

[0040] When the first voltage V1 of the first light-emitting unit 10 is lower than the second voltage V2 of the second light-emitting unit 20 and the first duty ratio Duty1 of the first light-emitting element 11 is lower than the second duty ratio Duty2 of the second light-emitting element 21, the first pulse forward current Ifp1 of the first light-emitting element 11 is likely to be high. In this case, it is preferable that the first integrated current value of the first light-emitting element 11 is lower than the second integrated current value of the second light-emitting element 21. This prevents the first pulse forward current Ifp1 of the first light-emitting element 11 from becoming too high, reduces a temperature rise in the first light-emitting element 11, and makes the first light-emitting element 11 less likely to break down.

[0041] When the second duty ratio Duty2 is set lower than the first duty ratio Duty1 (second duty ratio Duty2<first duty ratio Duty1), the first duty ratio Duty1 is preferably 20 times or less the second duty ratio Duty2. This prevents the first pulse forward current Ifp1 of the first light-emitting element 11 from becoming too high. When the first duty ratio Duty1 is set lower than the second duty ratio Duty2 (first duty ratio Duty1<second duty ratio Duty2), the second duty ratio Duty2 is preferably 20 times or less the first duty ratio Duty1. This prevents the second pulse forward current Ifp2 of the second light-emitting element 21 from becoming too high.

[0042] As shown in FIG. 4, the light source 1 according to the embodiment includes a substrate 200 and a plurality of light emitting devices 100. The light emitting devices 100 include a first light emitting element 11 and a second light emitting element 21. The substrate 200 supports the light emitting devices 100. The substrate 200 is also a wiring substrate that supplies power from a power source 30 to the first light emitting element 11 and the second light emitting element 21. The substrate 200 includes an insulating base material 102 and a wiring portion disposed on at least the upper surface of the insulating base material 102. The first light emitting element 11 and the second light emitting element 21 are electrically connected to the wiring portion. A detailed configuration of the light emitting device 100 will be described later.

[0043] A plurality of light emitting devices 100 are arranged on a substrate 200 side by side in a first direction X. In this embodiment, for example, one light emitting device 100 has one first light emitting element 11 and one second light emitting element 21. In each light emitting device 100, the first light emitting element 11 and the second light emitting element 21 are positioned side by side in the second direction Y. By positioning the first light emitting element 11 and the second light emitting element 21 side by side in the second direction Y in the light emitting device 100, the size of the light emitting device 100 and the light source 1 in the first direction X can be reduced.

[0044] When the duty ratio is high, the on-time during which current is supplied to the light-emitting element becomes longer, making it easier for the temperature of the light-emitting element to rise. Therefore, when the first duty ratio Duty1 of the first light-emitting element 11 is higher than the second duty ratio Duty2 of the second light-emitting element 21, it is preferable that the first light-emitting element 11 be positioned between the substrate 200 and the second light-emitting element 21 in the second direction Y in the light-emitting device 100. With this arrangement, the first light-emitting element 11 is positioned closer to the substrate 200 in the second direction Y than the second light-emitting element 21. That is, the shortest distance from the first light-emitting element 11 to the substrate 200 in the second direction Y is shorter than the shortest distance from the second light-emitting element 21 to the substrate 200 in the second direction Y. This makes it easier for heat generated by the first light-emitting element 11, whose temperature is more likely to rise than the second light-emitting element 21 due to its high duty ratio, to be dissipated to the substrate 200, thereby reducing the temperature rise of the first light-emitting element 11 and making it less susceptible to failure.

[0045] When the second duty ratio Duty2 of the second light-emitting element 21 is higher than the first duty ratio Duty1 of the first light-emitting element 11, in the light-emitting device 100, the second light-emitting element 21 is preferably positioned between the substrate 200 and the first light-emitting element 11 in the second direction Y. With this arrangement, the second light-emitting element 21 is positioned closer to the substrate 200 in the second direction Y than the first light-emitting element 11. That is, the shortest distance from the second light-emitting element 21 to the substrate 200 in the second direction Y is shorter than the shortest distance from the first light-emitting element 11 to the substrate 200 in the second direction Y. This makes it easier to dissipate heat generated by the second light-emitting element 21, which has a higher duty ratio and is therefore more likely to rise in temperature than the first light-emitting element 11, to the substrate 200, thereby reducing the temperature rise of the second light-emitting element 21 and making the second light-emitting element 21 less susceptible to failure.

[0046] Furthermore, when the integrated current value is high, the temperature of the light-emitting element is more likely to rise. Therefore, it is preferable to position the light-emitting element with the higher integrated current value, either the first light-emitting element 11 or the second light-emitting element 21, closer to the substrate 200 in the second direction Y than the light-emitting element with the lower integrated current value. In this way, the temperature rise of the light-emitting element with the higher integrated current value can be reduced.

[0047] In the first and second embodiments described above, multiple first light-emitting units 10 are connected in parallel to the power source 30, and the number of first light-emitting elements 11 connected in series in each first light-emitting unit 10 is greater than the number of first light-emitting units 10 connected in parallel. Increasing the number of first light-emitting elements 11 connected in series in a first light-emitting unit 10 reduces the variation in the value of the current flowing through each of the multiple first light-emitting elements 11 connected in series. This makes it easier to reduce the variation in the luminance of the multiple emitted first light-emitting elements 11. Furthermore, a configuration in which more first light-emitting elements 11 are connected in series between the power source 30 and the control unit 40 and the control unit 40 controls these multiple first light-emitting elements 11 to light up makes it easier to reduce the complexity of the wiring layout on the substrate 200. Furthermore, reducing the number of first light-emitting units 10 connected in parallel makes it easier to reduce the complexity of the wiring layout on the substrate 200. By reducing the complexity of the layout of the wiring portion on the substrate 200, the area of ​​the wiring portion formation region on the substrate 200 can be reduced, and the planar size of the substrate 200 can be made smaller.

[0048] Similarly, as shown in the first and second embodiments, it is preferable that a plurality of second light-emitting units 20 are connected in parallel to the power source 30, and that the number of second light-emitting elements 21 connected in series in each second light-emitting unit 20 is greater than the number of parallel connections of the plurality of second light-emitting units 20.

[0049] If the electrical resistance of wiring and the like is not taken into consideration, then, if the number of first light-emitting elements 11 connected in series in the first light-emitting unit 10 is Ns, then the first voltage V1 of the first light-emitting unit 10 = the first forward voltage Vf1 of the first light-emitting element 11 × Ns. As the number of series connections Ns increases, the first voltage V1 increases. If the number of parallel connections of the first light-emitting units 10, each of which has Ns first light-emitting elements 11 connected in series, is Np, then the same first voltage V1 is applied to all Np first light-emitting units 10. Even if the number of parallel connections Np is increased while the number of series connections Ns remains constant, the first voltage V1 does not increase. If an electrical open circuit failure (conduction failure) occurs in any one of the multiple first light-emitting elements 11 connected in series in the first light-emitting unit 10, the first light-emitting unit 10 including the first light-emitting element 11 with the open circuit failure will not light up. When the number Np of parallel connections of the first light-emitting units 10 is large, even if an open-failure first light-emitting element 11 occurs in one of the first light-emitting units 10, the other first light-emitting units 10 can light up, making it easier to reduce the total number of unlit first light-emitting elements 11. This makes it difficult for the brightness of the light source 1 to decrease even if an open-failure first light-emitting element 11 occurs in a first light-emitting unit 10. The above description also applies to the second light-emitting unit 20 and the second light-emitting element 21.

[0050] 1, the second light-emitting section 20 has a second light-emitting section first section 20A and a second light-emitting section second section 20B connected in parallel to a power source 30. The second light-emitting section first section 20A and the second light-emitting section second section 20B each have a plurality of second light-emitting elements 21 connected in series. The second light-emitting element 21 included in the second light-emitting section first section 20A is referred to as second light-emitting element 21A. The second light-emitting element 21 included in the second light-emitting section second section 20B is referred to as second light-emitting element 21B.

[0051] 4, in the first direction X in which the plurality of light-emitting devices 100 are arranged, the second light-emitting element 21B of the second light-emitting section second section 20B is located between two second light-emitting elements 21A of the second light-emitting section first section 20A. As a result, even if the second light-emitting element 21B of the second light-emitting section second section 20B goes unlit due to an electrical open defect (non-conduction defect), the second light-emitting element 21A of the second light-emitting section first section 20A located adjacent thereto in the first direction X can be lit, thereby making it easier to reduce uneven distribution of unlit areas. This makes it easier to reduce uneven brightness of the light source 1.

[0052] Furthermore, in the first direction X, the second light-emitting element 21A of the second light-emitting portion first section 20A is positioned between two second light-emitting elements 21B of the second light-emitting portion second section 20B. This allows the second light-emitting element 21B of the second light-emitting portion second section 20B, which is adjacent to the second light-emitting element 21A in the first direction X, to be lit even if the second light-emitting element 21A of the second light-emitting portion first section 20A goes unlit due to an electrical open fault or the like, thereby making it easier to reduce unevenly positioned unlit areas. This makes it easier to reduce uneven brightness of the light source 1.

[0053] As shown in FIG. 1, the first light-emitting section 10 has a first light-emitting section first unit 10A and a first light-emitting section second unit 10B connected in parallel to a power source 30. Each of the first light-emitting section first unit 10A and the first light-emitting section second unit 10B has a plurality of first light-emitting elements 11 connected in series. The first light-emitting element 11 included in the first light-emitting section first unit 10A is referred to as first light-emitting element 11A. The first light-emitting element 11 included in the first light-emitting section second unit 10B is referred to as first light-emitting element 11B.

[0054] 4, in the first direction X in which the plurality of light-emitting devices 100 are arranged, the first light-emitting element 11B of the first light-emitting section second section 10B is located between two first light-emitting elements 11A of the first light-emitting section first section 10A. As a result, even if the first light-emitting element 11B of the first light-emitting section second section 10B goes unlit due to an electrical open fault or the like, the first light-emitting element 11A of the first light-emitting section first section 10A located adjacent thereto in the first direction X can still be lit, making it easier to reduce unevenly positioned unlit areas. This makes it easier to reduce uneven brightness of the light source 1.

[0055] Furthermore, in the first direction X, the first light-emitting element 11A of the first light-emitting section first part 10A is positioned between two first light-emitting elements 11B of the first light-emitting section second part 10B. This makes it possible to reduce uneven distribution of unlit areas, even if the first light-emitting element 11A of the first light-emitting section first part 10A goes unlit due to an electrical open fault or the like.

[0056] <Light-emitting device> An example of a detailed configuration of the light emitting device 100 will be described with reference to FIGS.

[0057] The light emitting device 100 has a generally rectangular parallelepiped shape that is long in the first direction X. The light emitting device 100 has a light emitting surface 100A that is parallel to the XY plane. The light emitting surface 100A has a rectangular shape that is longer in the first direction X than in the second direction Y.

[0058] The light emitting device 100 includes a first light emitting element 11, a second light emitting element 21, a support member 101, a light reflective member 120, and a light transmissive member .

[0059] (First light-emitting element, second light-emitting element) Each of the first light-emitting element 11 and the second light-emitting element 21 has a semiconductor structure. The semiconductor structure includes an n-side semiconductor layer, a p-side semiconductor layer, and an active layer located between the n-side semiconductor layer and the p-side semiconductor layer. The active layer may have a single quantum well (SQW) structure or a multiple quantum well (MQW) structure including multiple well layers. The semiconductor structure includes multiple semiconductor layers made of nitride semiconductors. The nitride semiconductors include In x Al y Ga 1-x-y This includes semiconductors of all compositions in which the composition ratios x and y in the chemical formula N (0≦x, 0≦y, x+y≦1) are varied within their respective ranges.

[0060] The semiconductor structure may include multiple active layers. When the semiconductor structure includes multiple active layers, the emission peak wavelengths of the active layers may be the same or different. The emission peak wavelengths being the same also include cases where there is a variation of about several nanometers. The combination of different emission peak wavelengths in the multiple active layers can be selected appropriately.

[0061] Each of the first light emitting element 11 and the second light emitting element 21 may have a device substrate, and the semiconductor structure is formed on the device substrate, such as a sapphire substrate.

[0062] 9, the first light-emitting element 11 has an element light-emitting surface 11a and a mounting surface 11b located opposite the element light-emitting surface 11a. A positive electrode 181p electrically connected to the p-side semiconductor layer of the first light-emitting element 11 and a negative electrode 181n electrically connected to the n-side semiconductor layer of the first light-emitting element 11 are arranged on the mounting surface 11b of the first light-emitting element 11. As shown in FIG. 8, the second light-emitting element 21 has an element light-emitting surface 21a and a mounting surface 21b located opposite the element light-emitting surface 21a. A positive electrode 182p electrically connected to the p-side semiconductor layer of the second light-emitting element 21 and a negative electrode 182n electrically connected to the n-side semiconductor layer of the second light-emitting element 21 are arranged on the mounting surface 21b of the second light-emitting element 21.

[0063] (support member) The support member 101 supports the first light-emitting element 11, the second light-emitting element 21, the light-reflective member 120, and the light-transmitting member .

[0064] The support member 101 has an insulating substrate 102. The insulating substrate 102 may be made of, for example, resin, ceramic, or glass. The insulating substrate 102 may be made of a composite material, such as a fiber-reinforced resin, such as a glass epoxy substrate. Resins for the insulating substrate 102 may include, for example, bismaleimide triazine (BT), epoxy, or polyimide. Ceramics for the insulating substrate 102 may include, for example, aluminum oxide, aluminum nitride, zirconium oxide, zirconium nitride, titanium oxide, titanium nitride, or a mixture of two or more of these. It is advantageous to use a ceramic material for the insulating substrate 102 that has a linear expansion coefficient close to that of the first light-emitting element 11 and the second light-emitting element 21. The insulating substrate 102 has a first surface 102a and a second surface 102b located opposite the first surface 102a.

[0065] The support member 101 has external connection terminals 110 for electrically connecting the light emitting device 100 to the substrate 200 shown in FIG. 4. The external connection terminals 110 are arranged on the second surface 102b of the insulating base material 102. The external connection terminals 110 face the upper surface of the substrate 200 shown in FIG. 4 in the second direction Y. The external connection terminals 110 include a first external connection terminal 110A, a second external connection terminal 110B, a third external connection terminal 110C, and a fourth external connection terminal 110D. The first external connection terminal 110A, the second external connection terminal 110B, the third external connection terminal 110C, and the fourth external connection terminal 110D are aligned in the first direction X. The first external connection terminal 110A and the fourth external connection terminal 110D are located at both ends in the first direction X. In the first direction X, the second external connection terminal 110B and the third external connection terminal 110C are located between the first external connection terminal 110A and the fourth external connection terminal 110D. In the first direction X, the second external connection terminal 110B is located next to the first external connection terminal 110A, and the third external connection terminal 110C is located between the second external connection terminal 110B and the fourth external connection terminal 110D. In the first direction X, the first external connection terminal 110A and the second external connection terminal 110B are located apart, the second external connection terminal 110B and the third external connection terminal 110C are located apart, and the third external connection terminal 110C and the fourth external connection terminal 110D are located apart.

[0066] An insulating layer 103 is disposed on the back surface of the light emitting device 100 to prevent short circuits between two adjacent external connection terminals 110.

[0067] The support member 101 further includes a first conductive portion 301, a second conductive portion 302, a third conductive portion 303, a fourth conductive portion 304, a first connecting portion 401, a second connecting portion 402, a third connecting portion 403, and a fourth connecting portion 404. The first conductive portion 301, the second conductive portion 302, the third conductive portion 303, and the fourth conductive portion 304 are disposed on the first surface 102a of the insulating substrate 102. The first connecting portion 401, the second connecting portion 402, the third connecting portion 403, and the fourth connecting portion 404 penetrate between the first surface 102a and the second surface 102b of the insulating substrate 102.

[0068] As shown in FIG. 9 , the positive electrode 181p of the first light-emitting element 11 is bonded onto the first conductive portion 301, and is electrically connected to the first conductive portion 301. The negative electrode 181n of the first light-emitting element 11 is bonded onto the second conductive portion 302, and is electrically connected to the second conductive portion 302. The first connecting portion 401 electrically connects the first conductive portion 301 to the second external connection terminal 110B. The second connecting portion 402 electrically connects the second conductive portion 302 to the fourth external connection terminal 110D. The positive electrode 181p of the first light-emitting element 11 is electrically connected to the second external connection terminal 110B via the first conductive portion 301 and the first connecting portion 401. The negative electrode 181n of the first light emitting element 11 is electrically connected to the fourth external connection terminal 110D via the second conductive portion 302 and the second connection portion 402.

[0069] As shown in FIG. 8 , the positive electrode 182p of the second light-emitting element 21 is bonded onto the third conductive portion 303, and the positive electrode 182p of the second light-emitting element 21 is electrically connected to the third conductive portion 303. The negative electrode 182n of the second light-emitting element 21 is bonded onto the fourth conductive portion 304, and the negative electrode 182n of the second light-emitting element 21 is electrically connected to the fourth conductive portion 304. The third connector 403 electrically connects the third conductive portion 303 to the first external connection terminal 110A. The fourth connector 404 electrically connects the fourth conductive portion 304 to the third external connection terminal 110C. The positive electrode 182p of the second light-emitting element 21 is electrically connected to the first external connection terminal 110A via the third conductive portion 303 and the third connector 403. The negative electrode 182n of the second light emitting element 21 is electrically connected to the third external connection terminal 110C via the fourth conductive portion 304 and the fourth connection portion 404.

[0070] The first external connection terminal 110A, the second external connection terminal 110B, the third external connection terminal 110C, and the fourth external connection terminal 110D each have a recess 111. The recess 111 has openings on the lower and rear sides of the light emitting device 100. The lower surface of the light emitting device 100 faces the upper surface of the substrate 200 shown in FIG. 4. The rear surface of the light emitting device 100 is located on the opposite side to the light emitting surface 100A in the third direction Z. In a plan view of the rear surface of the light emitting device 100, the recess 111 has, for example, a semicircular shape. A conductive bonding member 150, such as solder, shown in FIG. 4 is disposed in the recess 111.

[0071] The external connection terminal 110 can be made of, for example, copper, iron, nickel, tungsten, chromium, aluminum, silver, platinum, gold, titanium, palladium, rhodium, or an alloy containing one or more of these metals. From the viewpoint of improving heat dissipation, it is preferable to use copper or a copper alloy as the material for the external connection terminal 110. The external connection terminal 110 may be a single-layer film or a multilayer film made of the above metal materials. If the outermost surface of the external connection terminal 110 is made of silver, platinum, aluminum, rhodium, gold, or an alloy containing one or more of these metals, good wettability of the joining member 150, such as solder, to the external connection terminal 110 can be obtained.

[0072] 4, the light emitting device 100 is placed on the upper surface of the substrate 200 with the light emitting surface 100A facing in the positive direction of the Z axis and the lower surface facing the upper surface of the substrate 200. A bonding member 150 placed in the recess 111 of the external connection terminal 110 is bonded to a wiring portion placed on the upper surface of the substrate 200. The first light emitting element 11 and the second light emitting element 21 are electrically connected to the wiring portion of the substrate 200 via the external connection terminal 110 and the bonding member 150.

[0073] The light source 1 according to this embodiment can be used, for example, as a light source for a backlight in a liquid crystal display device. Light emitted from the light-emitting surface 100A of the light-emitting device 100 is incident on a side surface of a light guide plate in the backlight. The light-emitting device 100 emits mixed light (e.g., white light) from the light-emitting surface 100A, which is a mixture of light emitted by the first light-emitting element 11, light emitted by the second light-emitting element 21, and wavelength-converted light by the translucent member 130 (described later).

[0074] In a plan view of the light-emitting surface 100A, the first light-emitting element 11 and the second light-emitting element 21 each have a rectangular shape whose length in the first direction X is longer than its length in the second direction Y. As described above, the first light-emitting element 11 and the second light-emitting element 21 are positioned side by side in the second direction Y. Because the long side of the first light-emitting element 11 and the long side of the second light-emitting element 21 are aligned opposite each other in the second direction Y, the light emitted by the first light-emitting element 11 and the light emitted by the second light-emitting element 21 are more easily mixed with reduced unevenness than when the short sides are aligned opposite each other in the second direction Y. This reduces color unevenness in the light emitted by the light-emitting device 100.

[0075] (Translucent member) The light-transmitting member 130 faces the element light-emitting surface 11a of the first light-emitting element 11 and the element light-emitting surface 21a of the second light-emitting element 21 in the third direction Z. The surface of the light-transmitting member 130 opposite to the surface facing the first light-emitting element 11 and the second light-emitting element 21 becomes the light-emitting surface 100A of the light-emitting device 100.

[0076] The light-transmitting member 130 is translucent to the light emitted by each of the first light-emitting element 11 and the second light-emitting element 21. The light-transmitting member 130 has a transmittance of, for example, 60% or more, preferably 70% or more, and more preferably 80% or more for light having a first emission peak wavelength of the first light-emitting element 11. The light-transmitting member 130 has a transmittance of, for example, 60% or more, preferably 70% or more, and more preferably 80% or more for light having a second emission peak wavelength of the second light-emitting element 21.

[0077] By covering both the first light-emitting element 11 and the second light-emitting element 21 with a single light-transmitting member 130, the light emitted by the first light-emitting element 11 and the light emitted by the second light-emitting element 21 can be efficiently mixed inside the light-transmitting member 130.

[0078] As shown in FIGS. 8 to 10 , the light-transmitting member 130 may have a protective layer 161 and a wavelength conversion layer 162. In the third direction Z, the wavelength conversion layer 162 is located between the support member 101 and the protective layer 161. The protective layer 161 protects the wavelength conversion layer 162. The wavelength conversion layer 162 includes a phosphor. For example, the phosphor absorbs part of the light (blue light) emitted by the first light-emitting element 11 and the light (green light) emitted by the second light-emitting element 21 to emit red light. As a result, the light emitted by the light-emitting device 100 can be made white by mixing the red light emitted by the phosphor, the blue light emitted by the first light-emitting element 11 and transmitted through the light-transmitting member 130, and the green light emitted by the second light-emitting element 21 and transmitted through the light-transmitting member 130.

[0079] The protective layer 161 and the wavelength conversion layer 162 have, as a base material, for example, a silicone resin, a modified silicone resin, an epoxy resin, a modified epoxy resin, a urea resin, a phenolic resin, a polycarbonate resin, a trimethylpentene resin, a polynorbornene resin, an acrylic resin, a urethane resin, or a fluororesin, or a resin containing two or more of these.

[0080] The phosphor is an yttrium-aluminum-garnet phosphor (e.g., Y3(Al,Ga)5O 12 :Ce), lutetium aluminum garnet phosphors (e.g., Lu3(Al,Ga)5O 12 :Ce), terbium aluminum garnet phosphors (e.g., Tb3(Al,Ga)5O 12 :Ce), CCA-based phosphors (e.g., Ca 10 (PO4)6Cl2:Eu), SAE-based phosphors (e.g., Sr4Al 14 O 25 :Eu), chlorosilicate phosphors (e.g., Ca8MgSiO 16Examples of phosphors that can be used include oxynitride phosphors, nitride phosphors, fluoride phosphors, phosphors with a perovskite structure (e.g., CsPb(F,Cl,Br,I)3), and quantum dot phosphors (e.g., CdSe, InP, AgInS2, or AgInSe2). Representative examples of oxynitride phosphors include β-sialon phosphors (e.g., (Si,Al)3(O,N)4:Eu) and α-sialon phosphors (e.g., Ca(Si,Al) 12 (O,N) 16 :Eu), etc. Representative examples of nitride-based phosphors include SLA-based phosphors (for example, SrLiAl3N4:Eu), CASN-based phosphors (for example, CaAlSiN3:Eu), and SCASN-based phosphors (for example, (Sr,Ca)AlSiN3:Eu). Representative examples of fluoride-based phosphors include KSF-based phosphors (e.g., K2SiF6:Mn), KSAF-based phosphors (e.g., K2Si 0.99 Al 0.01 F 5.99 :Mn) and MGF-based phosphors (e.g., 3.5MgO·0.5MgF2·GeO2:Mn).

[0081] The light-transmitting member 130 may contain one of the above-mentioned phosphors alone or two or more of them. When the light-transmitting member 130 contains two or more phosphors, it is beneficial to adjust the distribution of the phosphors in the light-transmitting member 130 so that the phosphor that emits light with a shorter wavelength is located near the first light-emitting element 11 and the second light-emitting element 21.

[0082] The light-transmitting member 130 may further include a light diffusion layer 164. The light diffusion layer 164 is disposed between the first light-emitting element 11 and the wavelength conversion layer 162, and between the second light-emitting element 21 and the wavelength conversion layer 162. The light diffusion layer 164 includes a base material made of the same material as the base materials of the protective layer 161 and the wavelength conversion layer 162, and a light diffusion material. The light diffusion material may be, for example, particles of a resin having a refractive index different from that of the base material, or particles of silicon oxide, aluminum oxide, zirconium oxide, or zinc oxide.

[0083] (Light-reflective member) In a plan view of the light-emitting surface 100A, the light-reflective member 120 surrounds the light-transmitting member 130, the first light-emitting element 11, and the second light-emitting element 21. The light-reflective member 120 is reflective to the light emitted by the first light-emitting element 11, the light emitted by the second light-emitting element 21, and the light emitted by the phosphor. The light-reflective member 120 has a reflectance of 60% or more, preferably 70% or more, and more preferably 80% or more for these lights. The light-reflective member 120 can increase the brightness in the front direction (positive direction of the Z axis) of the light-emitting device 100.

[0084] The light-reflecting member 120 includes, for example, a base material and light-scattering particles. Examples of the base material that can be used for the light-reflecting member 120 include silicone resin, modified silicone resin, epoxy resin, urea resin, polycarbonate resin, phenol resin, acrylic resin, urethane resin, fluororesin, or modified resins thereof, or resins containing two or more of these. The light-scattering particles have a higher refractive index than the base material. Examples of the light-scattering particles that can be used include particles of titanium oxide, magnesium oxide, zirconium dioxide, potassium titanate, aluminum oxide, aluminum nitride, boron nitride, mullite, niobium oxide, barium sulfate, silicon oxide, and various rare earth oxides (e.g., yttrium oxide and gadolinium oxide).

[0085] A recess 120A is formed on the front surface of the light-reflective member 120 facing the positive direction of the Z axis. The light-emitting surface 100A, which is the light extraction surface of the light-transmitting member 130, is located in the recess 120A of the light-reflective member 120. This makes the light-emitting surface 100A less likely to come into contact with external components and be damaged. Furthermore, when the light-emitting device 100 is bonded to the light guide plate with the light-emitting surface 100A facing the side surface of the light guide plate, an air layer is formed in the recess 120A. This reduces color unevenness in the light emitted from the light-emitting surface 100A.

[0086] (light-guiding member) The light emitting device 100 may further include a light guiding member 170. The light-transmissive member 130 is joined to the first light emitting element 11 and the second light emitting element 21 by the light guiding member 170. A resin material containing a transparent resin as a base material can be used as the material of the light guiding member 170. For example, the same material as the base material of the light-transmissive member 130 can be used as the base material of the light guiding member 170.

[0087] The light-guiding member 170 includes a portion located between the element side surface of the first light-emitting element 11 and the light-reflective member 120. A portion of the light emitted by the first light-emitting element 11 and exiting from the element side surface can be made incident on the light-transmissive member 130 by utilizing reflection at the interface between the light-guiding member 170 and the light-reflective member 120. The light-guiding member 170 includes a portion located between the element side surface of the second light-emitting element 21 and the light-reflective member 120. A portion of the light emitted by the second light-emitting element 21 and exiting from the element side surface can be made incident on the light-transmissive member 130 by utilizing reflection at the interface between the light-guiding member 170 and the light-reflective member 120. The light-guiding member 170 having such a function can improve the light extraction efficiency of the light-emitting device 100.

[0088] A light emitting device 100' according to a modified example of the embodiment will be described with reference to FIGS.

[0089] Light emitting device 100′ according to the modified example has two first light emitting elements 11 and two second light emitting elements 21. Two sets, each of which includes one first light emitting element 11 and one second light emitting element 21 aligned in second direction Y, are aligned in first direction X. Two first light emitting elements 11 are aligned in first direction X, and two second light emitting elements 21 are aligned in first direction X. In this example, no recess is formed on the front surface of light reflective member 120; however, as in light emitting device 100 shown in FIG. 5, light reflective member 120 may have a recess 120A on the front surface.

[0090] The light emitting device 100′ according to the modified example has, for example, six external connection terminals 110. The six external connection terminals 110 of this embodiment include one external connection terminal 110 electrically connected to the positive electrode of the first light emitting element 11 located on the +X side and one external connection terminal 110 electrically connected to the positive electrode of the second light emitting element 21 located on the +X side. The remaining four external connection terminals 110 include one external connection terminal 110 electrically connected to the negative electrode of the first light emitting element 11 located on the +X side and the positive electrode of the first light emitting element 11 located on the −X side, and one external connection terminal 110 electrically connected to the negative electrode of the second light emitting element 21 located on the +X side and the positive electrode of the second light emitting element 21 located on the −X side. The remaining two external connection terminals 110 include one external connection terminal 110 electrically connected to the negative electrode of the first light emitting element 11 located on the −X side and one external connection terminal 110 electrically connected to the negative electrode of the first light emitting element 11 located on the −X side. The electrical connections of the six external connection terminals 110 are not particularly limited. For example, the six external connection terminals 110 may include two external connection terminals 110 electrically connected to the positive electrodes of the two first light-emitting elements 11, respectively, and two external connection terminals 110 electrically connected to the positive electrodes of the two second light-emitting elements 21, respectively. One of the remaining two external connection terminals 110 may be commonly connected to the negative electrodes of the two first light-emitting elements 11, and the other may be commonly connected to the negative electrodes of the two second light-emitting elements 21.

[0091] The number of first light-emitting elements 11 and the number of second light-emitting elements 21 included in one light-emitting device are not limited to those shown in Fig. 5 or 11. Furthermore, in one light-emitting device, the number of first light-emitting elements 11 and the number of second light-emitting elements 21 are not limited to being the same, and the number of first light-emitting elements 11 and the number of second light-emitting elements 21 may be different.

[0092] In the light source according to the embodiment, both the first light-emitting element 11 and the second light-emitting element 21 may be driven by a continuous DC current rather than a pulse current during the light source's lighting period. In this case, for example, the first integrated current value of the first light-emitting element 11 having a shorter emission peak wavelength is higher than the second integrated current value of the second light-emitting element 21. As shown in FIG. 4 , the first light-emitting element 11 having a higher integrated current value is positioned closer to the substrate 200 in the second direction Y than the second light-emitting element 21 having a lower integrated current value. In other words, the shortest distance from the first light-emitting element 11 to the substrate 200 in the second direction Y is shorter than the shortest distance from the second light-emitting element 21 to the substrate 200 in the second direction Y. This reduces the temperature rise of the first light-emitting element 11 having a higher integrated current value.

[0093] Embodiments of the present disclosure can include the following light sources:

[0094] [Section 1] A substrate; a first light-emitting unit disposed on the substrate and having one or more first light-emitting elements connected in series; a second light-emitting unit disposed on the substrate and having a plurality of second light-emitting elements connected in series, the number of which is greater than the number of the first light-emitting elements; a power source that supplies power to the first light emitting element and the second light emitting element; a control unit that lights up the first light-emitting element and the second light-emitting element at a predetermined brightness; Equipped with the first light-emitting unit and the second light-emitting unit are connected in parallel to the power source; a first emission peak wavelength of the first light-emitting element is different from a second emission peak wavelength of the second light-emitting element, a second forward voltage of the second light emitting element is lower than a first forward voltage of the first light emitting element; a first voltage, which is a forward voltage in the first light-emitting unit, and a second voltage, which is a forward voltage in the second light-emitting unit, having an absolute value lower than the second forward voltage of the second light-emitting unit; [Section 2] the first voltage is lower than the second voltage; Item 1. The light source described in item 1, wherein the control unit controls the first duty ratio and the second duty ratio so that the first duty ratio of the first light-emitting element is lower than the second duty ratio of the second light-emitting element. [Section 3] the second voltage is lower than the first voltage; Item 1. The light source described in item 1, wherein the control unit controls the first duty ratio and the second duty ratio so that the second duty ratio of the second light-emitting element is lower than the first duty ratio of the first light-emitting element. [Section 4] 3. The light source according to item 2, wherein a first integrated current value of the first light emitting element is lower than a second integrated current value of the second light emitting element. [Section 5] Item 4. The light source according to item 3, wherein the second integrated current value of the second light emitting element is lower than the first integrated current value of the first light emitting element. [Section 6] Item 2 or 4. The light source according to item 2 or 4, wherein the second duty ratio is 20 times or less than the first duty ratio. [Section 7] Item 6. The light source according to item 3 or 5, wherein the first duty ratio is 20 times or less than the second duty ratio. [Section 8] a plurality of light emitting devices, each having the first light emitting element and the second light emitting element, are arranged on the substrate in a line in a first direction; Item 7. The light source according to item 2, 4, or 6, wherein the first light emitting element and the second light emitting element in the light emitting device are positioned side by side in a second direction perpendicular to the first direction. [Section 9] a plurality of light emitting devices, each having the first light emitting element and the second light emitting element, are arranged on the substrate in a line in a first direction; Item 8. The light source according to item 3, 5, or 7, wherein the first light emitting element and the second light emitting element in the light emitting device are positioned side by side in a second direction perpendicular to the first direction. [Section 10] Item 9. The light source according to item 8, wherein the shortest distance from the second light emitting element to the substrate in the second direction is shorter than the shortest distance from the first light emitting element to the substrate in the second direction. [Section 11] Item 10. The light source according to item 9, wherein the shortest distance from the first light emitting element to the substrate in the second direction is shorter than the shortest distance from the second light emitting element to the substrate in the second direction. [Section 12] a plurality of the first light-emitting units are connected in parallel to the power source; Item 12. The light source according to any one of items 1 to 11, wherein the number of the first light emitting elements connected in series in the first light emitting section is greater than the number of the first light emitting sections connected in parallel. [Section 13] the second light-emitting unit has a second light-emitting unit first part and a second light-emitting unit second part connected in parallel to the power supply, Item 10. The light source according to item 8 or 9, wherein the second light-emitting element of the second light-emitting section second part is located between two of the second light-emitting elements of the second light-emitting section first part in the first direction. [Section 14] a plurality of light emitting devices, each having the first light emitting element and the second light emitting element, are arranged on the substrate in a line in a first direction; a shortest distance from the first light-emitting element to the substrate in the second direction is shorter than a shortest distance from the second light-emitting element to the substrate in the second direction; Item 2. The light source according to item 1, wherein a first integrated current value of the first light emitting element is higher than a second integrated current value of the second light emitting element.

[0095] The embodiments of the present disclosure have been described above with reference to specific examples. However, the present disclosure is not limited to these specific examples. All forms that can be implemented by a person skilled in the art through appropriate design modifications based on the above-described embodiments of the present disclosure also fall within the scope of the present disclosure, as long as they include the gist of the present disclosure. In addition, within the scope of the concept of the present disclosure, a person skilled in the art may come up with various modifications and alterations, and these modifications and alterations also fall within the scope of the present disclosure. [Explanation of symbols]

[0096] 1...light source, 10...first light-emitting section, 10A...first light-emitting section first section, 10B...first light-emitting section second section, 11, 11A, 11B...first light-emitting element, 20...second light-emitting section, 20A...second light-emitting section first section, 20B...second light-emitting section second section, 21, 21A, 21B...second light-emitting element, 30...power source, 40...control section, 51...first wiring, 52...second wiring, 100, 100'...light-emitting device, 100A...light-emitting surface, 101...support member, 102...insulating base material, 103...insulating layer, 110...external connection terminal, 111...recess, 120...light-reflective member, 130...translucent member, 150...joint member, 200...substrate

Claims

1. A substrate; a first light-emitting unit disposed on the substrate and having one or more first light-emitting elements connected in series; a second light-emitting unit disposed on the substrate and having a plurality of second light-emitting elements connected in series, the number of which is greater than the number of the first light-emitting elements; a power source for supplying power to the first light emitting element and the second light emitting element; a control unit that lights up the first light-emitting element and the second light-emitting element at a predetermined brightness; Equipped with the first light-emitting unit and the second light-emitting unit are connected in parallel to the power source, a first emission peak wavelength of the first light-emitting element is different from a second emission peak wavelength of the second light-emitting element, a second forward voltage of the second light emitting element is lower than a first forward voltage of the first light emitting element; a first voltage being a forward voltage in the first light-emitting unit and a second voltage being a forward voltage in the second light-emitting unit, the absolute value of the difference being lower than the second forward voltage of the second light-emitting unit.

2. the first voltage is lower than the second voltage; The light source according to claim 1 , wherein the control unit controls the first duty ratio and the second duty ratio so that the first duty ratio of the first light-emitting element is lower than the second duty ratio of the second light-emitting element.

3. the second voltage is lower than the first voltage; The light source according to claim 1 , wherein the control unit controls the first duty ratio and the second duty ratio so that the second duty ratio of the second light-emitting element is lower than the first duty ratio of the first light-emitting element.

4. The light source according to claim 2 , wherein a first integrated current value of the first light-emitting element is lower than a second integrated current value of the second light-emitting element.

5. The light source according to claim 3 , wherein the second integrated current value of the second light emitting element is lower than the first integrated current value of the first light emitting element.

6. The light source of claim 2 , wherein the second duty ratio is 20 times or less than the first duty ratio.

7. The light source of claim 3 , wherein the first duty ratio is 20 times or less than the second duty ratio.

8. a plurality of light emitting devices, each having the first light emitting element and the second light emitting element, are arranged on the substrate in a line in a first direction; The light source according to claim 2 , wherein the first light emitting element and the second light emitting element in the light emitting device are positioned side by side in a second direction perpendicular to the first direction.

9. a plurality of light emitting devices, each having the first light emitting element and the second light emitting element, are arranged on the substrate in a line in a first direction; The light source according to claim 3 , wherein the first light emitting element and the second light emitting element in the light emitting device are positioned side by side in a second direction perpendicular to the first direction.

10. The light source according to claim 8 , wherein a shortest distance from the second light-emitting element to the substrate in the second direction is shorter than a shortest distance from the first light-emitting element to the substrate in the second direction.

11. The light source according to claim 9 , wherein a shortest distance from the first light-emitting element to the substrate in the second direction is shorter than a shortest distance from the second light-emitting element to the substrate in the second direction.

12. a plurality of the first light-emitting units are connected in parallel to the power source; The light source according to claim 1 , wherein the number of the first light-emitting elements connected in series in the first light-emitting section is greater than the number of the first light-emitting sections connected in parallel.

13. the second light-emitting unit has a second light-emitting unit first part and a second light-emitting unit second part connected in parallel to the power source, The light source according to claim 8 , wherein the second light-emitting element of the second part of the second light-emitting unit is located between two second light-emitting elements of the first part of the second light-emitting unit in the first direction.

14. a plurality of light emitting devices, each having the first light emitting element and the second light emitting element, are arranged on the substrate in a line in a first direction; a shortest distance from the first light-emitting element to the substrate in the second direction is shorter than a shortest distance from the second light-emitting element to the substrate in the second direction; The light source according to claim 1 , wherein a first integrated current value of the first light-emitting element is higher than a second integrated current value of the second light-emitting element.

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