Light-emitting device, lighting light source and lighting device

Abstract

Light-emitting device comprising: a substrate; a first light-emitting element that emits a first light and is mounted on the substrate; a second light-emitting element that emits a second light and is mounted at a position on the substrate where the second light-emitting element can receive the first light, wherein the second light has an emission peak wavelength that is longer than an emission peak wavelength of the first light; and a control and / or regulating device that separately controls and / or regulates the first light-emitting element and the second light-emitting element, wherein the control and / or regulating device controls and / or regulates a current to be supplied to the second light-emitting element on the basis of an electromotive force generated by the second light-emitting element, which receives the first light, the control and / or regulating device includes: a measuring device that measures a voltage value of the electromotive force generated by the second light-emitting element; a memory that stores a relationship between the voltage value of the electromotive force and a current value of the second light-emitting element; a determining device that determines the current value corresponding to the voltage value measured by the measuring device, based on the voltage value and the relationship stored in the memory; and an adjusting device that adjusts the current to be supplied to the second light-emitting element so that the current has the current value determined by the determining device.

Description

[Technical field]

[0001] The present invention relates to a light-emitting device, an illumination light source comprising the light-emitting device, and an illumination device comprising the light-emitting device. [State of the art]

[0002] Light-emitting semiconductor elements, such as LEDs (light-emitting diodes or light-emitting diodes), are widely used as efficient and space-saving light sources in various lighting devices for illumination, display, etc. purposes.

[0003] An LED has characteristics such that it generates heat as a result of emitting light, and this heat causes the LED's temperature to rise and its light output to decrease. In other words, the heat generated by the LED itself reduces its emission efficiency.

[0004] For example, an LED module is known that emits white light using a blue LED chip and a yellow phosphor. To improve the color rendering properties, a red LED chip can be added to the aforementioned setup. However, blue and red LED chips differ in the rate at which their light output decreases with temperature variation; that is, they exhibit different temperature characteristics. This causes a color shift in such an LED module. In other words, in an LED module that uses a combination of white light from the blue LED chip and the yellow phosphor, and red light from the red LED chip, a change in the color of the emitted light is easily perceived.

[0005] To reduce such color deviation, a light-emitting device has recently been developed which includes a temperature sensor and in which the ratio between the emission intensity of a red LED chip and the emission intensity of a blue LED chip is adjusted on the basis of the temperature detected by the temperature sensor (see, for example, patent document (PTL) 1). [Document List][Patent Document]

[0006] [PTL1] Japanese unexamined patent application with publication number JP 2007 - 318 050 A

[0007] DE 10 2006 023 694 A1 describes a planar light source device comprising a light source section with a plurality of light-emitting diodes as a light source and a light-conducting plate that directs light from the light source section to emit planar light. The light-emitting diodes that are switched off detect the light quantities from the other light-emitting diodes and adjust the amounts of light emission from the other light-emitting diodes based on the detected light quantities. [Summary of the invention][Technical problem]

[0008] However, incorporating a temperature sensor into a light-emitting device requires providing space for the temperature sensor within the light-emitting device, which leads to an increase in the size of the light-emitting device.

[0009] In light of the foregoing, it is an object of the present invention to reduce the overall size of a light-emitting device by controlling the emission intensity of different types of LED chips with different temperature characteristics without the use of a temperature sensor with respect to temperature. [Solution to the problem]

[0010] This problem is solved by the subject matter of the independent claims. Preferred embodiments are the subject matter of the dependent claims. [Advantageous effects of the invention]

[0011] According to the present invention, the emission intensity of different types of LED chips with different temperature characteristics is controlled without the use of a temperature sensor. As a result, the overall size of the light-emitting device can be reduced. [Brief description of the drawings] Fig. Figure 1 is a perspective view of the exterior of a light-emitting device according to embodiment 1. Fig. Figure 2 is a top view of the light-emitting device according to embodiment 1. Fig. Figure 3 is a top view of the internal structure of the light-emitting device according to embodiment 1. Fig. Figure 4 is a block diagram showing a control configuration of the light-emitting device according to embodiment 1. Fig. Figure 5 is a graph showing differences in the temperature characteristics between a first LED chip and a second LED chip according to embodiment 1. Fig. Figure 6 is a graph showing a relationship between the temperature of the second LED chip and a voltage value of the electromotive force according to embodiment 1. Fig. Figure 7 is a graph showing a relationship between the output ratio and the current value in the second LED chip according to embodiment 1. Fig. Figure 8 is a flowchart of an auxiliary control system according to embodiment 1. Fig. Figure 9 is a graph showing a relationship between the illumination period and the chromaticity or color value X in the light-emitting device according to embodiment 1. Fig. Figure 10 schematically shows a lightbulb-shaped lamp according to embodiment 2. Fig. Figure 11 is a cross-sectional view of a lighting device according to embodiment 3. Fig. Figure 12 is a perspective view of the exterior of the lighting device according to embodiment 3 and of additional components. [Description of embodiments]

[0012] A light-emitting device and the like, according to various embodiments, are described below with reference to the drawings. It should be noted that each of the embodiments described below represents a general or specific example. The numerical values, shapes, materials, structural components, arrangement, and connection of the structural components shown in the following embodiments are merely examples and are not intended to limit the present invention. In the following embodiments, those structural components not specified in any of the independent claims, which represent the broadest concepts of the invention, are described as any structural components.

[0013] Furthermore, the figures are schematic representations and not necessarily exact depictions. Additionally, components with the same essential structure use the same reference symbols in the drawings, and any duplicate descriptions of these components may be omitted or abbreviated in the description. [Version 1][Structure of the light-emitting device]

[0014] First, the construction of a light-emitting device according to embodiment 1 is described with reference to the drawings. Fig. Figure 1 is a perspective view of the exterior of the light-emitting device according to embodiment 1. Fig. Figure 2 is a top view of the light-emitting device according to embodiment 1. Fig. Figure 3 is a top view of the internal structure of the light-emitting device according to embodiment 1. Fig. Figure 3 is a top view of the internal structure, showing the arrangement and wiring pattern of LED chips 12, with the encapsulation element 13 and the boundary element 15 separated from the Fig. 2 are away.

[0015] As it is in the Fig. 1 to Fig. As shown in Figure 3, the light-emitting device 10 according to embodiment 1 comprises a substrate 11, a plurality of LED chips 12, an encapsulation element 13, a buffer layer 14 and a limiting element 15.

[0016] The light-emitting device 10 is a so-called COB chip mounting on the circuit board) LED module in which LED chips 12 are mounted directly on the substrate 11.

[0017] Substrate 11 is a rectangular substrate that includes wiring areas where wiring 16 and 17 are provided. Wiring 16 and 17 is metal wiring for supplying electrical current to the LED chips 12. Wiring 16 supplies electrical current to the first LED chips 12b of the LED chips 12. Wiring 17 supplies electrical current to the second LED chips 12r of the LED chips 12.

[0018] Substrate 11 is, for example, a metal-based substrate or a ceramic substrate. Examples of the ceramic substrate include an aluminum oxide substrate made from aluminum oxide and an aluminum nitride substrate made from aluminum nitride. Examples of the metal-based substrate include an aluminum alloy substrate, an iron alloy substrate, and a copper alloy substrate, each having a surface on which an insulating film is formed. Examples of the resin substrate include a glass-epoxy substrate made from glass fibers and an epoxy resin.

[0019] It should be noted that, for example, a substrate with very good optical reflectivity (e.g., an optical reflectivity of 90% or higher) can be used as substrate 11. Using a substrate with very good optical reflectivity as substrate 11 allows light emitted by the LED chips 12 to be reflected from the surface of the substrate 11. This leads to an increase in the light emission rate of the light-emitting device 10. Examples of substrates include a white ceramic substrate using aluminum oxide as the base material.

[0020] Alternatively, a translucent substrate with high light transmittance can be used as substrate 11. Examples of such a substrate include a translucent ceramic substrate made of polycrystalline aluminum oxide or aluminum nitride, a clear glass substrate made of glass, a crystal substrate made of crystal, a sapphire substrate made of sapphire, and a transparent resin substrate made of a transparent resin material.

[0021] Although the substrate 11 has a rectangular shape in embodiment 1, the substrate 11 can have a circular shape or another shape.

[0022] As it is in the Fig. As shown in Figure 3, the LED chips comprise 12 first LED chips 12b and second LED chips 12r.

[0023] The first LED chips 12b are examples of a first light-emitting element and are blue LED chips that emit blue light (first light). Examples of the first LED chips 12b include an LED chip formed using an InGaN-based material and exhibiting an emission peak wavelength (peak wavelength of the emission spectrum) in the range of 430 nm to 480 nm, inclusive. Each first LED chip 12b has a rectangular shape in plan view.

[0024] The second LED chips 12r are examples of a second light-emitting element and are, for example, red LED chips that emit red light (second light) with an emission peak wavelength longer than the emission peak wavelength of the first LED chips 12b. Examples of the second LED chips 12r include an LED chip formed using an AlGaInP-based material and having an emission peak wavelength in the range of 600 nm to 660 nm, inclusive. Each second LED chip 12r has a rectangular shape in plan view. In embodiment 1, an example is shown in which each first LED chip 12b has a rectangular shape in plan view and each second LED chip 12r has a square shape in plan view. These shapes are merely examples.The first LED chips 12b can have square shapes in the top view and the second LED chips 12r can have rectangular shapes in the top view, or both the first LED chips 12b and the second LED chips 12r can have rectangular or square shapes in the top view.

[0025] A plurality of light-emitting element rows and columns, each comprising a plurality of LED chips 12, is provided on the substrate 11. As shown in the Fig. As shown in Figure 3, a plurality of first light-emitting element columns 12B, each comprising first LED chips 12b, and a plurality of second light-emitting element columns 12R, each comprising second LED chips 12r, are provided. Specifically, three first light-emitting element columns 12B and two second light-emitting element columns 12R are provided. Each first light-emitting element column 12B comprises eighteen first LED chips 12b connected in series. The first light-emitting element columns 12B are connected in parallel between the positive and negative terminals of the wiring 16 and emit light when an electric current is supplied to the wiring 16. In contrast, each second light-emitting element column 12R comprises twenty-one second LED chips 12r connected in series.The second light-emitting element column 12R is connected in parallel between the positive and negative terminals of the wiring 17 and emits light when an electric current is supplied to the wiring 17. The wiring 16 and the wiring 17 are electrically independent of each other, and consequently the first light-emitting element column 12B, which is connected to the wiring 16, and the second light-emitting element column 12R, which is connected to the wiring 17, are electrically independent of each other.

[0026] Structurally, when the substrate 11 is considered as a whole, the first LED chips 12b and the second LED chips 12r are distributed approximately evenly across the substrate 11. Specifically, eight rows of light-emitting elements, each comprising both first LED chips 12b and second LED chips 12r, are arranged on the substrate 11 in a circular shape. In each row of light-emitting elements, three first LED chips 12b and three second LED chips 12r are arranged consecutively as sets. Adjacent first LED chips 12b and second LED chips 12r within each row of light-emitting elements are positioned such that the second LED chip 12r can receive light emitted by the adjacent first LED chip 12b.In particular, a first LED chip 12b and a second LED chip 12r, which are adjacent to each other, are arranged such that one side of the first LED chip 12b faces a side of the second LED chip 12r. In other words, one side of the second LED chip 12r faces a side of an adjacent first LED chip 12b. The distance H between the first LED chip 12b and the adjacent second LED chip 12r is less than the length of one side of the second LED chip 12r. This allows the second LED chip 12r to reliably receive light emitted by the adjacent first LED chip 12b.

[0027] In embodiment 1, since each of the second LED chips 12r has a square shape in plan view, the distance H is less than the length of one side of the second LED chip 12r. In the case where the second LED chip 12r has a rectangular shape in plan view, the distance H can be less than the shorter side of the second LED chip 12r. At least one set of the first LED chip 12b and the second LED chip 12r can be adjacent to each other. As long as the second LED chip 12r is positioned so that it can receive light emitted by the adjacent first LED chip 12b, one side of the first LED chip 12b need not be opposite a side of the adjacent second LED chip 12r.

[0028] Although no details are shown in the drawings, the LED chips 12, which are connected in series, are predominantly connected from chip to chip by the bond wire 18 (some of the LED chips 12 are connected by the wiring 16). For example, gold (Au), silver (Ag), or copper (Cu) are used as the metal material for the bond wire 18 as well as for the wiring 16 and 17 mentioned above.

[0029] The encapsulation element 13 is an encapsulation resin provided on the substrate 11, which encapsulates the LED chips 12, the bond wire 18, and the wiring 16 and 17. Specifically, the encapsulation element 13 directly encapsulates the first LED chips 12b of the LED chips 12. The encapsulation element 13 can have a flat or curved surface shape. The encapsulation element 13 is formed from a translucent resin material containing particles of a yellow phosphor and particles of a green phosphor as wavelength conversion elements. For example, a silicone resin is used as the translucent resin material; however, an epoxy resin, a urea resin, or the like can also be used. The phosphor particles are based on yttrium aluminum garnet (YAG) and yellow phosphors.

[0030] This arrangement transforms the wavelength of a portion of the blue light emitted by the first LED chips 12b into yellow light by the particles of the yellow phosphor contained in the encapsulating element 13. Similarly, the wavelength of a portion of the blue light emitted by the first LED chips 12b is transformed into green light by the particles of the green phosphor contained in the encapsulating element 13.The blue light that has not been absorbed by the particles of the yellow phosphor and the particles of the green phosphor, the yellow light resulting from the wavelength conversion by the particles of the yellow phosphor, the green light resulting from the wavelength conversion by the particles of the green phosphor, and the incident red light from the second LED chips 12r are distributed and mixed within the encapsulation element 13. Consequently, white light with improved color rendering properties is emitted from the encapsulation element 13.

[0031] It should be noted that the encapsulation element 13 also has a function of protecting the LED chips 12 and the bond wire 18 from dust, moisture, external force or the like.

[0032] The buffer layer 14 is a base layer formed on the substrate 11 to create the boundary element 15. In embodiment 1, the buffer layer 14 is a glass coating layer formed by coating the substrate 11 with glass.

[0033] In embodiment 1, the buffer layer 14 is configured to bridge the wiring areas and an area distinct from the wiring areas. Consequently, there are parts on the substrate 11 where the buffer layer 14 is configured to cover the wiring areas (wiring 16 and 17) (in the Fig. 3 shown), and a part in which the buffer layer 14 is formed directly on the substrate 11.

[0034] The buffer layer 14 is formed in a ring shape such that it partially covers the wiring 16 and 17 provided around the LED chips 12. In other words, the buffer layer 14 is formed in a ring shape such that it surrounds the LED chips 12 in a top view of the substrate 11. The outer shape of the buffer layer 14 can be a rectangular ring. The thickness of the buffer layer 14 is in the range of approximately 5 µm to approximately 50 µm.

[0035] The limiting element 15 is provided on the uppermost surface of the buffer layer 14 and serves to block the encapsulation element 13. The cross-sectional shape of the limiting element 15 is a protruding shape with the tip pointing upwards. For example, a thermosetting resin or a thermoplastic resin with insulating properties is used for the limiting element 15. In particular, a silicone resin, a phenolic resin, an epoxy resin, a BT (bismaleimide triazine) resin, PPA (polyphthalamide), or the like is used for the limiting element 15.

[0036] It is preferred that the limiting element 15 be light-reflecting, thus increasing the light emission efficiency of the light-emitting device 10. For this purpose, a white-colored resin (referred to as white resin) is used for the limiting element 15. It should be noted that particles of, for example, TiO2, Al2O3, ZrO2, or MgO can be incorporated into the limiting element 15 to further increase its light reflection.

[0037] As it is in the Fig. As shown in Figure 2, a limiting element 15 in the light-emitting device 10 is formed in a ring shape such that it surrounds the LED chips 12 in a top view of the substrate 11. The area enclosed by the limiting element 15 is filled with the encapsulating element 13. This makes it possible to improve the light emission efficiency of the light-emitting device 10. It should be noted that the outer shape of the limiting element 15 can be a rectangular ring shape, as is the case with the buffer layer 14.

[0038] Next, a control setup of the light-emitting device 10 according to embodiment 1 is described. Fig. Figure 4 is a block diagram showing a control structure of the light-emitting device according to embodiment 1. As shown in the Fig. As shown in Figure 4, the light-emitting device 10 comprises a control unit 20 which separately controls the first LED chips 12b and the second LED chips 12r based on the electric current supplied by a power supply device (not shown). As shown in the Fig. As shown in Figure 4, the control device 20 functionally comprises a first light emitter 21, a measuring device 30 and a second light emitter 22.

[0039] The first light emitter 21 is a microcomputer electrically connected to the wiring 16. By supplying current to the first LED chips 12b via the wiring 16, the first LED chips 12b are switched on. The first light emitter 21 can control the light output of the first LED chips 12b by adjusting the current value for the first LED chips 12b. For example, if an output setting signal is supplied to the first light emitter 21 by a control unit, such as a remote control (not shown), the first light emitter 21 adjusts the current value so that the light output of the first LED chips 12b corresponds to the output setting signal.

[0040] The measuring device 30 is a voltmeter electrically connected to the wiring 17 and measures the voltage value of the electromotive force generated by every second LED chip 12r adjacent to a first LED chip 12b and receiving light from an adjacent first LED chip 12b. As a general characteristic of LED chips, when an LED chip with an emission peak wavelength of a predetermined wavelength (second LED chip 12r in embodiment 1) receives light with a wavelength shorter than the predetermined wavelength (light emitted by the first LED chip 12b in embodiment 1), the second LED chip 12r photoelectrically generates an electromotive force. Since the measuring device 30 receives the electromotive force via the wiring 17, it measures the voltage value of the electromotive force and outputs the measured voltage value to the second light emitter 22.

[0041] The second light emitter 22 is a microcomputer electrically connected to the wiring 17. By supplying current to the second LED chips 12r via the wiring 17, the second LED chips 12r are switched on. The second light emitter 22 includes, for example, a CPU (central processing unit), a RAM (random access memory), and a ROM (read-only memory). The CPU controls the second LED chips 12r by executing a program stored in the ROM within the RAM. Although embodiment 1 shows an example in which the first light emitter 21 and the second light emitter 22 are different microcomputers, the first light emitter 21 and the second light emitter 22 can also be a single microcomputer.

[0042] The second light emitter 22 can control the light output of the second LED chips 12r by controlling a current value for the second LED chips 12r. For example, if an output setting signal is supplied to the second light emitter 22 by a control unit, such as a remote control or controller (not shown), the second light emitter 22 controls the current value such that the light output of the second LED chips 12r corresponds to the output setting signal.

[0043] In the case where the first LED chip 12b and the second LED chip 12r, which have different temperature characteristics, are present together, the problem of color deviation occurs, as mentioned above. Fig. Figure 5 is a graph showing differences in the temperature characteristics between the first LED chips and the second LED chips according to embodiment 1. In the Fig. Figure 5 represents the relative values ​​of the light output from the first LED chips 12b and the second LED chips 12r on the vertical axis when the light output (luminous flux) is 1 at a given temperature (e.g. 25 °C).

[0044] As it is in the Fig. As shown in Figure 5, the light output from the first LED chips 12b and the light output from the second LED chips 12r decreases with increasing junction temperature (Tj). However, the rate of decrease differs between the first LED chips 12b and the second LED chips 12r.

[0045] In particular, the rate of reduction in light output from the first LED chips 12b with respect to temperature increase is lower than that of the second LED chips 12r. Simply put, the first LED chips 12b exhibit better temperature characteristics than the second LED chips 12r. In other words, the rate of reduction in light output from the second LED chips 12r with respect to temperature increase is greater than that of the first LED chips 12b. Simply put, the second LED chips 12r exhibit worse temperature characteristics than the first LED chips 12b.

[0046] As a result, the difference between the light output from the first LED chips 12b and the light output from the second LED chips 12r increases with increasing time after the start of light emission by the light-emitting device 10. The change (increase) in the difference in light output is perceived as a color deviation in the light emitted by the light-emitting device 10.

[0047] To reduce color deviation, the second light emitter 22 controls the current value for the second LED chips 12r based on the electromotive force generated by each second LED chip 12r adjacent to a first LED chip 12b and receiving light emitted by the adjacent first LED chip 12b. In other words, the second light emitter 22 performs two different control operations: control based on an output setting signal from a control unit and control (auxiliary control) based on the electromotive force.

[0048] As it is in the Fig. As shown in Figure 4, the second light emitter 22 functionally comprises a memory 221, a determination device 222 and an adjustment device 223.

[0049] Memory 221 stores a relationship between the voltage value of the electromotive force and the current value of the second LED chips 12r. This relationship shows the extent to which the current value for the second LED chips 12r must be adjusted to correct the color deviation when the voltage value of the electromotive force is at a given value. In embodiment 1, the relationship is represented by a plurality of tables. In particular, memory 221 stores three tables: an electromotive force versus temperature table 221a, a temperature versus output ratio table 221b, and an output ratio versus current value table 221c.

[0050] The electromotive force versus temperature table 221a is a table that shows a relationship between the voltage value of the electromotive force generated by the second LED chips 12r and the temperature of the second LED chips 12r. Fig. Figure 6 is a graph showing a relationship between the temperature of the second LED chips and the voltage value of the electromotive force according to embodiment 1. The electromotive force versus temperature table 221a is based on Fig. 6 generated. In other words, the temperature of the second LED chip 12r can be estimated on the basis of the voltage value measured by the measuring device 30 and the electromotive force against temperature - Table 221a.

[0051] The temperature versus output ratio table 221b is a table that shows a relationship between the temperature of the second LED chips 12r and the output ratio of the emission intensity (light output) of the first LED chips 12b and the second LED chips 12r. The temperature versus output ratio table 221b is generated based on the graph shown in the Fig. Figure 5 shows that the output ratio of the first LED chip 12b and the second LED chip 12r can be estimated based on the estimated temperature of the second LED chip 12r and the temperature against output ratio table 221b. For example, in the case of temperature tn in the Fig. 5, if the emission intensity of the second LED chips is 12r L, the emission intensity of the first LED chips is 12b 1.2 LDh, the emission ratio is 1.2.

[0052] The one in Fig. Table 221c, showing the ratio of emission intensity to current, is a table that shows a relationship between the ratio of emission intensity (light output) of the first LED chips 12b and the second LED chips 12r and the current value for the second LED chips 12r. Fig. Figure 7 is a graph showing the relationship between the output ratio and the current value in the second LED chip according to embodiment 1. The output ratio versus current value table 221c is based on Fig. 7 generated. It should be noted that in the Fig. 7. The output ratio is 1.0 when the current is 100 mA. In other words, the current for the second LED chips 12r can be estimated based on the estimated output ratio and the output ratio versus current value table 221c. For example, if the output ratio at temperature tn is 1.2, as described above, the current for the second LED chips 12r is 125 mA. Supplying current with the estimated current value to the second LED chips 12r causes the output ratio of the second LED chips 12r and the first LED chips 12b to approach 1.0, resulting in a reduction of the color deviation.

[0053] The determining device 222 determines a current value corresponding to the voltage value measured by the measuring device 30 based on the voltage value and the relationships stored in the memory 221. In particular, the determining device 222 determines a current value based on the voltage value measured by the measuring device 30 and the electromotive force versus temperature table 221a, the temperature versus output ratio table 221b, and the output ratio versus current value table 221c, which are stored in the memory 221.

[0054] The adjusting device 223 sets a current to be supplied to the second LED chips 12r such that the current has the value determined by the determining device 222. In this way, the difference in temperature characteristics between the first LED chips 12b and the second LED chips 12r is reduced, which leads to a reduction in the color deviation caused by the difference in temperature characteristics.

[0055] Next, the process of the auxiliary control will be described with reference to the Fig. 8 described. Fig. Figure 8 is a flowchart of the auxiliary control according to embodiment 1.

[0056] As it is in the Fig. As shown in Figure 8, in step S1 the control device 20 first switches off the second LED chips 12r and switches on the first LED chips 12b, causing the second LED chips 12r, which are adjacent to the first LED chips 12b, to receive light emitted by the adjacent first LED chips 12b and generate an electromotive force. The voltage value VF1 of the electromotive force of the second LED chips 12r is then measured.

[0057] In step S2, the control unit 20 waits for a first predefined period (e.g., 5 µs) and proceeds to step S3. During this waiting period, the control unit 20 keeps the first LED chips 12b and the second LED chips 12r switched on ("ON").

[0058] In step S3, the control unit 20 switches off the second LED chips 12r and switches on the first LED chips 12b, causing the second LED chips 12r, which are adjacent to the first LED chips 12b, to receive light emitted by the adjacent first LED chips 12b and generate an electromotive force. The voltage value VF2 of the electromotive force of the second LED chips 12r is then measured after the first predetermined period.

[0059] In step S4, the control unit 20 determines whether the voltage value VF1 is equal to the voltage value VF2 and terminates the auxiliary control if it is determined that the voltage values ​​VF1 and VF2 are identical. If it is determined that the voltage values ​​VF1 and VF2 are different, the control unit 20 proceeds to step S5. Even if the voltage values ​​VF1 and VF2 are not completely identical, they can be determined to be identical if they lie within a predefined range.

[0060] In step S5, the control unit 20 determines a current value for the second LED chips 12r based on the voltage value VF2. In particular, the control unit 20 determines the current value based on the voltage value VF2, the electromotive force versus temperature (Table 221a), the temperature versus output ratio (Table 221b), and the output ratio versus current value (Table 221c).

[0061] In step S6, the control unit 20 sets a current that is to be supplied to the second LED chips 12r, so that the current has the specified current value.

[0062] In step S7, the control unit 20 waits for a second predefined period and then proceeds to step S1. The second predefined period is longer than the first predefined period.

[0063] The Fig. Figure 9 is a graph showing a relationship between the illumination period and the chromaticity or color value X in the light-emitting device 10 according to embodiment 1. As shown in the Fig. As shown in Figure 9, the chromaticity X decreases with increasing illumination time. The second predefined period can be determined with respect to this relationship. The second predefined period can vary according to the illumination time.

[0064] As described above, in the auxiliary control, steps S1 to S7 are repeated until the voltage value VF1 becomes identical to the voltage value VF2, i.e., until the temperature is stabilized. Repeating steps S1 to S7 balances the emission intensities (light output) of the first LED chips 12b and the second LED chips 12r, resulting in a reduction of color deviation. [Advantageous effects, etc.]

[0065] As described above, the light-emitting device 10 according to embodiment 1 comprises first LED chips 12b, second LED chips 12r, and the control device 20. The first LED chips 12b are first light-emitting elements mounted on the substrate 11. Each of the second LED chips 12r is a second light-emitting element mounted on the substrate 11 at a position such that the second LED chip 12r can receive light emitted by a first LED chip 12b. Each second LED chip 12r has an emission peak wavelength that is longer than the emission peak wavelength of each first LED chip 12b. The control device 20 controls the first LED chips 12b and the second LED chips 12r separately.Furthermore, the control device 20 controls a current to be supplied to the second LED chips 12r, based on the electromotive force generated by the second LED chips 12r, which receive light emitted by the first LED chips 12b.

[0066] This design allows the current supplied to the second LED chip 12r to be controlled based on the electromotive force generated by the second LED chip 12r. Consequently, the emission intensity can be controlled with respect to temperature without directly measuring the temperature. This eliminates the need for a temperature sensor, thus reducing the overall size of the device.

[0067] Furthermore, the control unit 20 comprises a measuring unit 30, a memory 221, a determining unit 222, and an adjusting unit 223. The measuring unit 30 measures the voltage value of the electromotive force generated by the second LED chips 12r. The memory 221 stores a relationship between the voltage value of the electromotive force and the current value of the second LED chips 12r. Based on the voltage value measured by the measuring unit 30 and the relationships stored in the memory 221, the determining unit 222 determines a current value corresponding to the voltage value. The adjusting unit 223 sets a current to be supplied to the second LED chips 12r such that the current has the value determined by the determining unit 222.

[0068] With such a setup, the second LED chip 12r can be controlled on the basis of the voltage value measured by the measuring device 30 and the current value determined on the basis of the relationships stored in the memory 221.

[0069] In embodiment 1, the memory 221 stores three tables: the electromotive force versus temperature table 221a, the temperature versus output ratio table 221b, and the output ratio versus current value table 221c. The current value corresponding to the voltage value of the electromotive force is obtained indirectly using the electromotive force versus temperature table 221a, the temperature versus output ratio table 221b, and the output ratio versus current value table 221c. However, if an electromotive force versus current value table is generated that specifies a relationship between the voltage value of the electromotive force and the current value, the current value corresponding to the voltage value can be obtained directly from such a table.The electromotive force versus current table can be generated by combining the electromotive force versus temperature table 221a, the temperature versus output ratio table 221b, and the output ratio versus current table 221c. Furthermore, the electromotive force versus current table can be generated by conducting various experiments and simulations.

[0070] The first LED chips 12b and the second LED chips 12r each have rectangular shapes when viewed from above. A second LED chip 12r adjacent to a first LED chip 12b is arranged such that one side of the second LED chip 12r faces a side of the first LED chip 12b. The distance H between the first LED chip 12b and the adjacent second LED chip 12r is less than one side (short side) of the second LED chip 12r.

[0071] With such a setup, a second LED chip 12r, adjacent to a first LED chip 12b, can reliably receive light emitted by an adjacent first LED chip 12b, since the distance H between the first LED chip 12b and the adjacent second LED chip 12r is shorter than one side of the second LED chip 12r.

[0072] The first LED chips 12b and the second LED chips 12r are encapsulated by the same encapsulation element 13 (encapsulation resin).

[0073] If the first LED chips 12b and the second LED chips 12r are encapsulated by different encapsulating resins, some of the light emitted by the first LED chips 12b may be refracted or reflected by the interface of the encapsulating resins. In this case, the amount of light received by the second LED chips 12r is reduced. Conversely, the aforementioned limitation can be eliminated by encapsulating the first LED chips 12b and the second LED chips 12r together with the same encapsulating resin, thus preventing any reduction in the amount of light received by the second LED chips 12r. [Version 2]

[0074] Next, the construction of an incandescent lamp-shaped lamp 90 according to embodiment 2 is described with reference to the Fig. 10 described. The Fig. Figure 10 schematically shows a filament-shaped lamp 90 according to embodiment 2.

[0075] The one in Fig. The incandescent lamp 90 shown in Figure 10 is an example of a lighting light source and comprises the light-emitting device 10 according to embodiment 1. The incandescent lamp 90 comprises: a translucent bulb 91; a light-emitting device 10 which serves as a light source; a housing 96 in which a control circuit for supplying electric current to the light-emitting device 10 is included; and a base 98 which receives electric current from the outside.

[0076] The alternating current obtained through the base 98 is converted into direct current by the control circuit and supplied to the light-emitting device 10. If direct current is supplied to the base 98, the control circuit does not need to have a function of converting alternating current to direct current.

[0077] In embodiment 2, the light-emitting device 10 is arranged in a central section of the piston 91 by means of support by a support column 93. The support column 93 is a metal rod that extends from a section near the opening of the piston 91 to the interior of the piston 91.

[0078] In particular, the support column 93 is connected to a support plate 94, which is located near the opening of the piston 91.

[0079] The light-emitting device 10 can be supported directly by the support plate 94 instead of the support column 93. In other words, the light-emitting device 10 can be supported on a surface on the side of the piston 91 of the support plate 94.

[0080] The bulb 91 is a translucent cover that allows light emitted by the light-emitting device 10 to pass through to the outside. According to embodiment 2, the bulb 91 is made of a material that is transparent to light emitted by the light-emitting device 10. For example, a glass bulb (transparent bulb) made of quartz glass, which is transparent to visible light, is used for the bulb 91.

[0081] In this case, the light-emitting device 10, which is included in the piston 91, is visible from outside the piston 91.

[0082] It should be noted that the bulb 91 need not necessarily be transparent to visible light and can be designed to scatter light. For example, a resin, a white pigment, or the like, containing a light-scattering material such as silicon dioxide or calcium carbonate, is applied to the entire inner or outer surface of the bulb 91, forming a milky light-scattering film. Furthermore, the material of the bulb 91 is not limited to glass; a material made from a resin, such as a synthetic acrylic resin (polymethyl methacrylate (PMMA)) or a synthetic polycarbonate resin (PC), can be used.

[0083] The shape of the piston 91 is not specifically restricted. For example, a hemispherical piston 91 can be used if the light-emitting device 10 is directly supported by the support plate 94 (if no support column 93 is provided).

[0084] Since the incandescent lamp 90 comprises the light-emitting device 10 according to embodiment 1, very good color rendering properties can be provided as described in embodiment 1 and it is less likely that a color deviation will be perceived.

[0085] In embodiment 2 an example was shown in which the incandescent lamp 90 is an illumination light source which includes the light-emitting device 10 according to embodiment 1, however an illumination light source which includes the light-emitting device 10 can be implemented as a straight tube lamp. [Version 3]

[0086] Next, a lighting device 100 according to embodiment 3 is described with reference to the Fig. 11 and the Fig. 12 described. The Fig. Figure 11 is a cross-sectional view of a lighting device according to embodiment 3. Fig. Figure 12 is a perspective view of the exterior of the lighting device according to embodiment 3 and of additional components.

[0087] As it is in the Fig. 11 and the Fig. As shown in Figure 12, the lighting device 100 according to embodiment 3 is a recessed lighting device, such as a recessed light fixture, which, by being installed, for example, in the ceiling of a house, emits light downwards (e.g., in the direction of the floor or a wall).

[0088] The lighting device 100 comprises a light-emitting device 10 according to embodiment 1. The lighting device 100 further comprises: a device body essentially in the form of a tube with a bottom, formed by connecting a base 110 and a frame 120; and a reflective plate 130 and a translucent plate 140 arranged on the device body.

[0089] The base 110 is a mounting platform to which the light-emitting device 10 is attached and also serves as a heat sink for dissipating heat generated by the light-emitting device 10. The base 110 is essentially formed in a column shape using a metal material and, in embodiment 3, is made of die-cast aluminum.

[0090] A plurality of heat-dissipating fins 111 are arranged at predetermined intervals along a single direction on the uppermost section (the ceiling-side section) of the base 110, projecting upwards. This allows the heat generated by the light-emitting device 10 to be efficiently dissipated.

[0091] The frame 120 comprises: a conical section 121, which includes a reflective surface on an inner surface and has a substantially circular tubular shape; and a frame body 122 to which the conical section 121 is attached. The conical section 121 is formed using a metallic material and can, for example, be made of an aluminum alloy or the like by metal spinning or pressing. The frame body 122 is formed of a hard resin material or a metallic material. The frame 120 is fixed by the frame body 122, which is attached to the base 110.

[0092] The reflecting plate 130 is an annular, frame-shaped (funnel-shaped) reflecting element with an internal surface reflection function. For example, the reflecting plate 130 can be made using a metallic material, such as aluminum. It should be noted that the reflecting plate 130 can also be made using a hard white resin material instead of a metallic material.

[0093] The translucent panel 140 is a translucent element with light-diffusing and light-transmitting properties. The translucent panel 140 is a flat panel positioned between the reflective panel 130 and the frame 120, and it is attached to the reflective panel 130. For example, the translucent panel 140 can be formed into a disc shape using a transparent resin material, such as acrylic or polycarbonate.

[0094] It should be noted that the lighting device 100 does not necessarily have to include the translucent panel 140. Without the translucent panel 140, the luminous flux of light emitted by the lighting device 100 can be increased.

[0095] Furthermore, as stated in the Fig. As shown in Figure 12, the lighting device 150 and the connection base 160 are connected to the lighting device 100. The lighting device 150 supplies lighting energy to the light-emitting device 10. The connection base 160 supplies alternating current from a mains power supply to the lighting device 150.

[0096] The lighting device 150 and the connection base 160 are attached to a mounting plate 170, which is provided separately from the device body. The mounting plate 170 is formed by bending a rectangular sheet of metal. The lighting device 150 is attached to the lower surface at one end along the longitudinal direction of the mounting plate 170. The connection base 160 is attached to the lower surface at the other end along the longitudinal direction of the mounting plate 170. The mounting plate 170 and the top plate 180, which is attached to the uppermost section of the base 110 of the device body, are connected to each other.

[0097] Since the lighting device 100 comprises the light-emitting device 10 according to embodiment 1, very good color rendering properties can be provided as described in embodiment 1 and it is less likely that a color deviation will be perceived. (Other embodiments)

[0098] Although a light-emitting device, an illumination light source and an illumination device according to the present invention have been described on the basis of embodiments 1 to 3, the present invention is not limited to the embodiments described above.

[0099] For example, the light-emitting device 10 according to embodiment 1 emits white light using a combination of first LED chips 12b with a yellow phosphor, but the setup for emitting white light is not limited to such a setup.

[0100] For example, the first LED chips 12b can be combined with a phosphor-containing resin that includes a red phosphor and a green phosphor. Alternatively, an ultraviolet LED chip that emits ultraviolet light with a wavelength shorter than that of the light emitted by the LED chips 12b can be combined with blue phosphor particles, green phosphor particles, and red phosphor particles that emit blue light, green light, and red light, respectively, as a result of excitation primarily by ultraviolet light.

[0101] Furthermore, it was described that LED chips, such as the first LED chips 12b, are used as light-emitting elements incorporated into the light-emitting device 10. However, SMD (surface-mount device) LED elements can also be used as light-emitting elements incorporated into the light-emitting device 10.

[0102] It should be noted that forms obtained by various modifications of the foregoing embodiments, which are apparent to a person skilled in the art, as well as forms realized by any combination of structural elements and functions in the embodiments which are within the scope of the essentials of the present invention, are included in the present invention. [List of reference symbols] 10 Light-emitting device 11 Substrat 12b First LED chips (first light-emitting elements) 12r Second LED chips (second light-emitting elements) 20 Control unit 30 Measuring device 90 lightbulb-shaped lamp (lighting light source) 100 lighting device 221 storage 222 Destination facility 223 Adjustment device

Claims

[1] Light-emitting device comprising: a substrate; a first light-emitting element that emits a first light and is mounted on the substrate; a second light-emitting element that emits a second light and is mounted at a position on the substrate where the second light-emitting element can receive the first light, wherein the second light has an emission peak wavelength that is longer than an emission peak wavelength of the first light; and a control and / or regulating device that separately controls and / or regulates the first light-emitting element and the second light-emitting element, wherein the control and / or regulating device controls and / or regulates a current to be supplied to the second light-emitting element on the basis of an electromotive force generated by the second light-emitting element, which receives the first light, the control and / or regulating device includes: a measuring device that measures a voltage value of the electromotive force generated by the second light-emitting element; a memory that stores a relationship between the voltage value of the electromotive force and a current value of the second light-emitting element; a determining device that determines the current value corresponding to the voltage value measured by the measuring device, based on the voltage value and the relationship stored in the memory; and an adjusting device that adjusts the current to be supplied to the second light-emitting element so that the current has the current value determined by the determining device. [2] Light-emitting device according to claim 1, wherein each of the first light-emitting element and the second light-emitting element is rectangular in plan view, the second light-emitting element is arranged such that one side of the second light-emitting element is opposite a side of the first light-emitting element, and a distance between the first light-emitting element and the second light-emitting element is less than the length of a short side of the second light-emitting element. [3] Light-emitting device according to one of claims 1 to 2, wherein the first light-emitting element and the second light-emitting element are encapsulated by the same encapsulation resin. [4] Lighting light source comprising the light-emitting device according to any one of claims 1 to 3. [5] Lighting device comprising the light-emitting device according to any one of claims 1 to 3.

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