JP2010206085A - Light emitting device, lighting system and method of driving the lighting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting device holding a light color approximately the same and a quantity of light to be approximately constant without being affected by change of a quantity of light due to deterioration with age of a light emitting section, a lighting system equipped with the light emitting device, and a method of driving the lighting system. <P>SOLUTION: In a lighting system 100 including a light emitting section 1 and a control section 4 for controlling a drive current for driving the light emitting section 1, the control section 4 is constituted such that the drive current to be supplied to the light emitting section 1 is changed according to the total operating time of the light emitting section 1 to obtain a predetermined quantity of light. Since an amount of a decrease in the quantity of light associated with the total operating time is compensated with an amount of an increase in the quantity of light according to an increase in the drive current, the quantity of light can be held approximately constant without being affected by change of the quantity of light due to deterioration with age of each of an LED 11, 12 and 13. As a result, a ratio of the light emissions of the red LED 11, the green LED 12 and the blue LED 13 having different luminescent colors does not change, so that a light color can be held to be approximately the same. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a light emitting device configured to control a driving current for driving a light emitting unit, an illumination device including the light emitting device, and a method for driving the illumination device.

  Conventionally, incandescent bulbs or fluorescent lamps have been widely used as light sources for lighting devices. In recent years, as light-emitting diodes (hereinafter referred to as LEDs), which are solid-state light-emitting elements using semiconductors, have increased in brightness, LEDs having characteristics such as low power consumption and long life have been replaced with light sources for lighting devices. It is used as.

  In the illuminating device using the LED as the light source, conventionally, there is an illuminating device configured to obtain a desired light color by using a plurality of LEDs having different emission colors and mixing the light from the plurality of LEDs. For example, a red LED, a green LED, and a blue LED are used to obtain white light. Moreover, in such an illuminating device, it is possible to adjust the light emission ratio of each of the red LED, the green LED, and the blue LED to obtain various light colors such as a light bulb color and a color color.

  However, when the LED is used for a long time, the LED element, the sealing resin for sealing the LED element, and the like are deteriorated, and the amount of light is reduced. The decrease in the amount of light accompanying the total use time differs depending on the type of red LED, green LED, blue LED, and the like. For example, the deterioration with the total use time is faster for the blue LED than for the red LED and the green LED. In particular, the blue LED is said to deteriorate rapidly when the total use time exceeds several thousand hours.

  For this reason, in order to obtain desired white light as illumination light at the time of initial setting, even when the light emission ratio of each of the red LED, green LED and blue LED is optimally set, the light emission ratio changes with time, and as a result, The illumination light obtained by mixing these three lights deviates from the desired white light. Accordingly, various lighting devices configured to obtain substantially the same light color even when time has elapsed have been proposed (see, for example, Patent Document 1).

  The LED illumination device disclosed in Patent Document 1 includes a plurality of LEDs that output light of different wavelengths, and a drive unit that drives each LED independently for each emission wavelength, and the drive unit includes a plurality of LEDs. Each LED is driven by a current value having the same temporal change. With this configuration, the change over time of each LED is the same, and even if time elapses, the light emission ratio of the plurality of LEDs remains the same, so the color of the illumination light formed by mixing the light from the plurality of LEDs Does not change, and substantially the same light color can be obtained.

JP 2007-80532 A

  However, in the LED lighting device according to Patent Document 1, since a constant current determined so that changes with time of a plurality of LEDs are the same is supplied to each LED, as described above, due to deterioration of the LEDs. There has been a problem that the amount of light decreases according to the total use time and becomes dark.

  The present invention has been made in view of such circumstances, and can keep the light color substantially the same and can keep the light amount substantially constant without being affected by the light amount change due to the temporal change of the light emitting portion. It is an object to provide a light emitting device, a lighting device including the light emitting device, and a driving method of the lighting device.

  A light-emitting device according to the present invention includes a light-emitting unit and a control unit that controls a drive current that drives the light-emitting unit, and the control unit uses the light-emitting unit in total to obtain a predetermined amount of light. The driving current supplied to the light emitting unit is changed according to time.

  In the present invention, in order to obtain a predetermined amount of light, the drive current supplied to the light emitting unit is changed according to the total usage time of the light emitting unit. When the light amount of the light emitting unit changes due to the temporal change of the light emitting unit, the light amount can be kept substantially constant by changing the drive current according to the amount of change in the light amount. Further, for example, when the present invention is applied to a light emitting device including a plurality of LEDs having different emission colors, the light emission ratio of the plurality of LEDs does not change, so that the light colors can be kept substantially the same.

  The light emitting device according to the present invention includes means for accumulating the usage time of the light emitting unit to obtain a total usage time, and a table indicating a relationship between the total usage time of the light emitting unit and a drive current, The drive current is obtained by applying the total usage time of the light emitting unit obtained by the means to the table, and the drive current supplied to the light emitting unit is changed to the obtained drive current. To do.

  In the present invention, the total usage time is obtained by accumulating the usage time of the light emitting unit, and the obtained total usage time is applied to a table indicating the relationship between the total usage time of the light emitting unit and the driving current. The current is obtained, and the drive current supplied to the light emitting unit is changed to the obtained drive current. By appropriately setting the table in consideration of the change in the amount of light accompanying the total usage time of the light emitting unit, the amount of light can be held substantially constant without being affected by the change in the amount of light due to the temporal change of the light emitting unit. Become. Further, for example, when the present invention is applied to a light emitting device including a plurality of LEDs having different emission colors, the light emission ratio of the plurality of LEDs does not change, so that the light colors can be kept substantially the same.

  In the light-emitting device according to the present invention, the light-emitting unit includes a plurality of light sources having different emission colors, and the control unit uses a driving current of at least one light source among the plurality of light sources as a total usage time of the light source. It is configured to change according to the above.

  In the present invention, the driving current of at least one light source of the light emitting unit including a plurality of light sources having different emission colors is changed according to the total use time of the light source. As a light source that is changed according to the total usage time, for example, by selecting a light source that has the fastest deterioration due to the total usage time, it is possible to effectively suppress changes in light color and light amount with a simple configuration.

  The light emitting device according to the present invention is characterized in that the drive current supplied to each of the plurality of light sources is determined such that the change in the amount of light with respect to the total use time is substantially the same between the plurality of light sources.

  In the present invention, the drive current supplied to each of the plurality of light sources is determined so that the change in the amount of light with respect to the total use time is substantially the same between the plurality of light sources. Since the change in the amount of light with respect to the total usage time of a plurality of light sources is substantially the same, the total usage time for changing the drive current and the change rate of the drive current can be made the same, and the light color is substantially the same with a simple control configuration And the amount of light can be kept substantially constant.

  The light emitting device according to the present invention includes a light amount sensor that detects a light amount of the light emitting unit, and the control unit corrects a target value of a drive current supplied to the light emitting unit based on a detection value by the light amount sensor. It is configured as described above.

  In the present invention, the light amount of the light emitting unit is detected by the light amount sensor, and the target value of the drive current supplied to the light emitting unit is corrected based on the detected light amount. For example, since the actual light amount of the light emitting unit is detected at the start of use or during use of the light emitting device, it is possible to correct the variation in the initial light amount between the lots of the light emitting unit and the variation over time.

  The light emitting device according to the present invention is characterized in that the light emitting section includes an LED.

  In the present invention, the light emitting unit includes an LED, and since the light amount of the LED increases in proportion to the increase of the drive current, the light emitting unit changes according to the decrease in the light amount accompanying the deterioration of the light emitting unit. The drive current to be supplied can be easily set.

  An illumination device according to the present invention includes the light-emitting device according to the above-described invention, and is configured to emit light from the light-emitting device as illumination light.

  In the present invention, since the light emitting device is provided and the light from the light emitting device is emitted as illumination light, it is substantially the same without being affected by the change in the light amount due to the temporal change of the light emitting unit. Illumination light with a substantially constant light quantity and a constant light quantity can be obtained.

  The driving method of the lighting device according to the present invention is the driving method of the lighting device according to the above-described invention, wherein a life curve indicating a light amount change with respect to the total use time of the light emitting unit is obtained in advance using the driving current as a parameter. Based on the life curve, the driving current supplied to the light emitting unit is determined according to the total usage time so that the light amount of the light emitting unit becomes substantially constant, and the determined driving current is supplied to the light emitting unit. The light emitting unit is driven.

  In the present invention, a life curve indicating a change in light amount with respect to the total use time of the light emitting unit is obtained in advance using the drive current as a parameter, and the drive current supplied to the light emitting unit is set to the total use time based on the obtained life curve. Accordingly, the light amount of the light emitting unit is determined to be substantially constant, and the determined drive current is supplied to the light emitting unit to drive the light emitting unit. Therefore, the light color can be kept substantially the same, and the light amount can be kept substantially constant.

  According to the present invention, the light color can be kept substantially the same and the light amount can be kept substantially constant without being affected by the change in the light amount due to the temporal change of the light emitting unit.

1 is a block diagram showing a schematic configuration of a lighting device according to Embodiment 1. FIG. It is a figure which shows a time-dependent change of the light quantity of red LED, green LED, and blue LED. It is a figure which shows the relationship between the total use time t of red LED, green LED, and blue LED, and the drive current I from which the light quantity E becomes fixed with respect to the total use time t. It is a figure which shows the time-dependent change of the light quantity E of LED with respect to the drive current I used for the illuminating device which concerns on Embodiment 1. FIG. 4 is a diagram showing a relationship between a total use time t of LEDs used in the lighting apparatus according to Embodiment 1 and a drive current I. FIG. It is explanatory drawing of the other change method of the drive current. It is a flowchart which shows the process sequence of lighting control of the illuminating device of a control part. 6 is a block diagram illustrating a schematic configuration of a lighting device according to Embodiment 2. FIG. It is explanatory drawing of the correction method of the target value of the drive current. It is a flowchart which shows the other process sequence of lighting control of the illuminating device of a control part. It is a flowchart which shows the other process sequence of lighting control of the illuminating device of a control part. FIG. 10 is an explanatory diagram for setting a drive current I in the third embodiment.

Hereinafter, the present invention will be described in detail with reference to the drawings showing the embodiments, taking an illuminating device as an example.
(Embodiment 1)
FIG. 1 is a block diagram showing a schematic configuration of illumination apparatus 100 according to Embodiment 1. As shown in FIG. In the figure, reference numeral 1 denotes a light emitting unit having a plurality of light sources having different emission colors. The light emitting unit 1 includes a red LED 11 whose emission color is red, a green LED 12 whose emission color is green, and a blue LED 13 whose emission color is blue. The red LED 11, the green LED 12, and the blue LED 13 are surface mounted LEDs each including an LED element, a sealing resin that seals the LED element, and an input terminal and an output terminal.

  The red LED 11, green LED 12, and blue LED 13 of the light emitting unit 1 are connected to drive circuits 21, 22, and 23 that operate to supply predetermined drive currents to the red LED 11, green LED 12, and blue LED 13, respectively. . A DC power supply unit 3 that supplies power to the light emitting unit 1 is connected to the drive circuits 21, 22, and 23 through the drive circuits 21, 22, and 23.

  The DC power supply unit 3 includes a rectifier circuit that rectifies a current supplied from a commercial AC power supply, a transformer that converts the rectified voltage into a predetermined voltage, and the like. The DC power supply unit 3 rectifies the AC current supplied from the commercial AC power source and converts it into a predetermined voltage, and supplies the DC current to the drive circuits 21, 22, and 23, respectively.

  The drive circuits 21, 22, and 23 are connected to a control unit 4 that controls a drive current for driving the light emitting unit 1. The control unit 4 includes a control microcomputer and is configured to generate signals to be supplied to the drive circuits 21, 22, and 23.

  A DC power supply unit 3 is connected to the control unit 4, and power for a control operation with a predetermined voltage is supplied from the DC power supply unit 3. The control unit 4 includes a control program, setting contents, a memory 5 that stores the total use time of each of the red LED 11, the green LED 12, and the blue LED 13, a timer 6 that counts the time, and an operation unit 7 that receives a human operation. Is connected. The total use time is obtained by accumulating the use time in which each of the red LED 11, the green LED 12, and the blue LED 13 actually counted by the timer 6 is lit in the control unit 4.

  The operation unit 7 includes, for example, a power switch that accepts an operation to turn on / off the light emitting unit 1, a light emission color setting switch that accepts a setting operation of a light emission color such as daylight white, light bulb color, and an illuminance that accepts a brightness setting operation An infrared remote controller including a setting switch and a transmission unit that transmits an infrared signal in accordance with the operation of the switches.

  The control unit 4 receives a signal given by the operation unit 7 by a receiving unit (not shown), and also controls a dimming control program stored in the memory 5, and each of the red LED 11, the green LED 12, and the blue LED 13. Read the total usage time.

  The control unit 4 obtains a duty ratio corresponding to the signal so as to set the light emission ratio of the red LED 11, the green LED 12 and the blue LED 13 of the light emitting unit 1 so that the light emission color set by the operation unit 7 is obtained. A control program for generating a pulse signal with a duty ratio is executed to generate a pulse signal with the duty ratio. The control unit 4 gives the generated pulse signal to the drive circuit units 21, 22 and 23.

  In addition, the control unit 4 obtains a drive current for each of the red LED 11, the green LED 12, and the blue LED 13, and sends a command signal for changing the obtained drive current to the drive current supplied to the light emitting unit 1 to the drive circuit units 21, 22, and 23. give.

  The drive circuits 21, 22, and 23 are configured so that the red LED 11, the green LED 12, and the blue LED 13 have a predetermined light emission ratio corresponding to a light emission color such as daylight white or light bulb color. A switching element such as a field effect transistor for supplying / cutting off the power is provided. The drive circuits 21, 22, and 23 increase or decrease the drive current supplied to each of the red LED 11, green LED 12, and blue LED 13 of the light-emitting unit 1, and set the drive current after increase / decrease to be a constant current. A constant current circuit configured to be supplied to each of the LED 12 and the blue LED 13 is provided.

  The constant current circuits and switching elements of the drive circuits 21, 22, and 23 operate according to the signal given by the control unit 4, and according to this operation, the red LED 11, the green LED 12, and the blue LED 13 of the light emitting unit 1 are respectively Then, the light is turned on at a predetermined light emission intensity determined by the control unit 4, and light of a predetermined light color and light amount is emitted from the illumination device 100 as illumination light.

  In the illuminating device 100 according to the present invention, the drive current supplied to the red LED 11, the green LED 12, and the blue LED 13 of the light emitting unit 1 in this way depends on the total usage time of the red LED 11, the green LED 12, and the blue LED 13, respectively. In other words, it is configured to change according to the light amount decrease accompanying the change with time. Hereinafter, the concept of changing the drive current will be described.

  First, the temporal change of the light amount of each of the red LED 11, the green LED 12, and the blue LED 13 used in the illumination device 100 is obtained in advance. FIG. 2 is a diagram showing temporal changes in the light amounts of the red LED 11, the green LED 12, and the blue LED 13. The horizontal axis of FIG. 2 indicates the total usage time t of each LED 11, 12, 13, and the vertical axis indicates the light amount E of each LED 11, 12, 13, respectively. 2A shows the change over time of the light amount of the red LED 11, FIG. 2B shows the change over time of the light amount of the green LED 12, and FIG. 2C shows the change over time of the light amount of the blue LED 13. .

  This change with time is obtained, for example, by performing an acceleration test in which acceleration with temperature is performed. This accelerated test is a test method that predicts the lifetime at the operating temperature by measuring the time to reach the lifetime under different temperature conditions and plotting the measured data using the Arrhenius model formula. Therefore, detailed description of the test method is omitted. The change with time shown in FIG. 2 is obtained from the life curve by Arrhenius plot. Note that the operating temperature is appropriately set according to the installation environment of the lighting device 100 to which the light emitting unit 1 is attached, the heat dissipation structure, and the like.

  As shown in FIG. 2, the light quantity E of each LED 11, 12, 13 decreases as the total usage time t increases. As shown in FIG. 2 (c), since the light quantity E of the blue LED 13 decreases rapidly, when used as it is, only the light quantity of illumination light, which is a mixed light of the LEDs 11, 12, 13, is reduced. In addition, since the light emission ratios of the LEDs 11, 12, and 13 change with time, the light color also changes. Therefore, the amount of decrease in the light amount accompanying the change over time is compensated by the increase in the amount of light according to the increase in the drive current supplied to each of the red LED 11, the green LED 12 and the blue LED 13. The light quantity E of each of the red LED 11, the green LED 12, and the blue LED 13 can be kept constant without being affected by the light quantity change.

  FIG. 3 is a diagram illustrating the relationship between the total usage time t of the red LED 11, the green LED 12, and the blue LED 13 and the drive current I at which the light amount E is constant with respect to the total usage time t. The horizontal axis in FIG. 3 indicates the total usage time t of each LED 11, 12, 13, and the vertical axis indicates the drive current I supplied to each LED 11, 12, 13, respectively. 3A shows the drive current I supplied to the red LED 11 for the total use time t of the red LED 11, and FIG. 3B shows the drive current I supplied to the green LED 12 for the total use time t of the green LED 12. FIG. 3C shows the driving current I supplied to the blue LED 13 with respect to the total usage time t of the blue LED 13. Based on FIG. 3, the drive current I corresponding to the total usage time t of each LED 11, 12, 13 is supplied to each LED 11, 12, 13. The light quantity of each LED11,12,13 can be made constant, without receiving.

  As shown in FIG. 3, it is preferable to continuously change the drive current I according to the total use time t from the viewpoint of making the light quantity E of each LED 11, 12, 13 constant. From the viewpoint, in the present embodiment, the following description will be given by taking as an example an illumination device 100 configured to change the drive current I so that the light amount E falls within a predetermined range.

  FIG. 4 is a diagram illustrating a change with time of the light amount E of the LED with respect to the drive current I used in the lighting apparatus 100 according to Embodiment 1, and is an explanatory diagram of a method for changing the drive current I. The horizontal axis of FIG. 4 indicates the total usage time t of the LED, and the vertical axis indicates the light quantity E of the LED. The change with time of the light quantity of the LED is obtained for each drive current Ii (Ii = I1, I2, I3, I4...: I1 <I2 <I3 <I4). As shown in FIG. 4, in general, the amount of light E increases as the drive current I increases, and the change with time and the rate of change of the amount of light E with respect to the total usage time t also increase. In FIG. 4, for convenience of explanation, only the diagram showing the temporal change in the light amount of one type of LED is shown and the other diagrams are omitted, but in reality, the three types of red LED 11, green LED 12, and The figure which shows the time-dependent change of the light quantity of each blue LED13 is calculated | required previously.

  E1 is an initial light amount, and E2 is a threshold light amount. E2 is slightly lower than E1, and is set to such an extent that the user does not feel uncomfortable. The drive current I supplied to each of the LEDs 11, 12, 13 of the light emitting unit 1 is changed so that the light amount E falls within a range between E1 and E2. Note that E2 is appropriately set according to the structure of the illumination device 100 to which the light emitting unit 1 is attached, the cover, and the like.

  More specifically, at the start of use of the illumination device 100, the initial drive current I1 is set, and the amount of light E gradually decreases from E1 according to the total use time t as shown in FIG. When the total usage time t reaches the predetermined time t1 when the light amount E decreases from the initial light amount E1 to E2, the drive current I supplied to the light emitting unit 1 is changed from I1 to I2 so that the light amount E becomes E1. When the total usage time t reaches the predetermined time t2 when the light amount E decreases to E2 in the drive current I2, the drive current I supplied to the light emitting unit 1 is changed from I2 to I3 so that the light amount E becomes E1. Similarly, when the total usage time t reaches the predetermined time t3, the drive current I is changed from I3 to I4. Thereafter, the same is repeated, and the relationship between the total use time t and the drive current I is obtained over the lifetime of the lighting device 100. The obtained results are shown in FIG.

  FIG. 5 is a diagram showing the relationship between the total usage time t of the LEDs used in the lighting apparatus 100 according to Embodiment 1 and the drive current I. The horizontal axis in FIG. 5 represents the total usage time t of the LED, and the vertical axis represents the drive current I. As shown in FIG. 5, by changing the drive current I in a stepped manner according to the total use time t of the LEDs, the LEDs 11, 12, and 13 are hardly affected by the change in light quantity due to changes over time. , 12 and 13 can be made substantially constant in a range between E1 and E2, as indicated by a thick line in FIG.

  In FIG. 4, when the total usage time t reaches the predetermined time t1 when the light amount E decreases from the initial light amount E1 to E2, the drive current I supplied to the light emitting unit 1 is set so that the light amount E becomes E1. By changing from I1 to I2, the temporal change of the light quantity E is considered from the time when the total use time t = t1 in the drive current I2. However, as described above, as the drive current I increases, the change with time increases and the rate of change of the light quantity E with respect to the total use time t also increases. Therefore, the deterioration state of the LED at the time of the predetermined time t1 in the drive current I1 This is different from the degradation state of the LED at the predetermined time t1 in the drive current I2. Therefore, when considering the temporal change of the light amount E in the drive current I2, it is more preferable to consider the temporal change of the light amount E from the time at which the total usage time t is shorter than t1, that is, at the left position in the figure from t1. FIG. 6 shows an idea that is accurate and corrects this deviation.

  FIG. 6 is an explanatory diagram of another method for changing the drive current I. The horizontal axis of FIG. 6 represents the total use time t of the LED, and the vertical axis represents the light quantity E of the LED. The change with time of the light quantity of the LED is obtained for each driving current Ii (Ii = I1, I2 ', I3', I4 '...: I1 <I2' <I3 '<I4'). At the start of use of the illumination device 100, the initial drive current I1 is set, and the light amount E gradually decreases from E1 according to the total use time t as shown in FIG. When the total usage time t reaches the predetermined time t1 when the light amount E decreases from the initial light amount E1 to E2, the drive current I supplied to the light emitting unit 1 is changed from I1 to I2 ′ so that the light amount E becomes E1. . At this time, as indicated by a thick line in FIG. 6, the start point of the total use time in the drive current I2 'is set to be shorter than t1. Thereafter, the same is repeated, and the relationship between the total use time t and the drive current I is obtained over the lifetime of the lighting device 100. The obtained results are longer than those in FIG. 5 between t1 and t2, between t2 and t3, and between t3 and t4 by the correction amount. By performing such correction, it becomes possible to make the light quantity E of each LED 11, 12, 13 more nearly constant within a range sandwiched between E1 and E2. In addition, it is necessary to perform such correction | amendment appropriately according to the structure etc. of the illuminating device 100 which attaches the light emission part 1. FIG.

  As described above, a life curve indicating a change with time of the light amount E with respect to the total usage time t of the light emitting unit 1 is obtained in advance using the drive current I as a parameter, and based on the obtained life curve, as described above, the red LED 11, the green LED 12, and A table indicating the relationship between the total use time t and the drive current I of each of the blue LEDs 13 (for example, a table showing the relationship between the total use time t and the drive current I in FIG. 5) is obtained, and the obtained table is stored in the memory 5. Is stored in advance. The control unit 4 changes the drive current for each of the red LED 11, the green LED 12, and the blue LED 13 to the drive current I obtained by applying the total usage time t of each LED 11, 12, 13 to the table.

  FIG. 7 is a flowchart illustrating a processing procedure of lighting control of the lighting device 100 of the control unit 4. After the lighting device 100 is turned on, the control unit 4 acquires a signal from the operation unit 7 and takes in setting information of emission colors such as daylight white color and light bulb color (step S1). Next, the total use time t of each of the red LED 11, green LED 12 and blue LED 13 stored in the memory 5 is read (step S2), and each of the red LED 11, green LED 12 and blue LED 13 stored in the memory 5 is read. The target value of the drive current I to be supplied is read (step S3). At the start of use of the lighting device 100, the drive current I is the initial drive current I1.

  Based on the setting information of the emission color captured in step S1, the RGB ratio, which is the emission ratio of the red LED 11, the green LED 12, and the blue LED 13, stored in the memory 5 is read (step S4). This RGB ratio is set in advance according to the type of light emission color. For example, in white white (5000K), R: G: B is 0.8: 1: 0.3, and the light bulb color (2800K). In this case, R: G: B is set to 1: 0.9: 0.1.

  The drive current I according to the target value of the drive current I of each LED 11, 12, 13 read in step S 3 and the set value such as the RGB ratio read in step S 4 is used as the red LED 11, green LED 12, and blue of the light emitting unit 1. The LED 13 is supplied to each of the LEDs 13 to turn on the lighting device 100 (step S5), and the timer 6 is started.

  Based on the lighting time counted by the timer 6, the usage times of the red LED 11, the green LED 12 and the blue LED 13 are accumulated to obtain the total usage time t (step S 6), and the total usage time t is stored in the memory 5. Remember. The usage time is obtained by multiplying the lighting time by the RGB ratio. For example, in the case of lighting for 8 hours in white white, the usage time of the red LED is 6.4 hours, the usage time of the green LED is 8 hours, and the usage time of the blue LED is 2.4 hours. The total usage time t is obtained by adding the usage times corresponding to the total usage time t of each LED 11, 12, 13 read in step S2.

  Next, using the total use time t obtained in step S6, whether the total use time t is a predetermined time ti (i = 1, 2, 3,...) Is determined for each of the red LED 11, the green LED 12, and the blue LED 13. (Step S7). In step S7, when the total usage time t is the predetermined time ti (step S7: YES), the drive current I is changed (step S8), the process proceeds to step S9, and the target value of the changed drive current I is set. Store in the memory 5. On the other hand, if the total usage time t is not the predetermined time ti in step S7 (step S7: NO), the process proceeds to step S9 without changing the drive current I. The drive current I is changed by changing the drive current for each of the red LED 11, the green LED 12, and the blue LED 13 to the drive current I obtained by applying the total use time t of each LED 11, 12, 13 to the table. Is made by

  Next, in step S9, it is determined whether or not there is a change in emission color. This determination is made based on whether or not there is an input to the emission color setting information from the operation unit 7.

  In step S9, when there is a change in emission color (step S9: YES), the process returns to step S4 and repeats a series of operations until the power is shut off. On the other hand, if there is no change in the emission color in step S9 (step S9: NO), the process returns to step S5 and repeats a series of operations until the power is shut off.

  In the illumination device 100 according to Embodiment 1 configured as described above, the total usage time t is obtained by accumulating the usage time of each of the red LED 11, the green LED 12, and the blue LED 13 of the light emitting unit 1, and the obtained total usage. The time t is applied to a table indicating the relationship between the total usage time t of each LED 11, 12, 13 and the drive current I to determine the drive current I, and the calculated drive current I is supplied to each LED 11, 12, 13 The driving current is changed. As described above, the table is set so that the decrease in the light amount E associated with the total usage time t of each of the LEDs 11, 12, and 13 is compensated by the increase in the light amount E corresponding to the increase in the drive current I. Therefore, the light quantity can be kept substantially constant without being affected by the change in the light quantity due to the aging of each LED 11, 12, and 13. As a result, the light emission ratios of the red LED 11, the green LED 12, and the blue LED 13 having different emission colors do not change, so that the light colors can be kept substantially the same.

  Further, the above-described effects can be obtained with a simple configuration by appropriately setting a control program or the like stored in the memory 5 without using a sensor for detecting the amount of light. Further, since the light quantity E of the LED increases in proportion to the increase of the drive current I, each ED 11, which is changed according to the decrease of the light quantity E accompanying the deterioration of the red LED 11, the green LED 12, and the blue LED 13 of the light emitting unit 1, The drive current I to be supplied to 12 and 13 can be set easily.

(Embodiment 2)
FIG. 8 is a block diagram showing a schematic configuration of lighting apparatus 200 according to Embodiment 2. In FIG. A light receiving sensor 8 as a light amount sensor is provided at an appropriate position where light from the red LED 11, green LED 12, and blue LED 13 of the light emitting unit 1 of the lighting device 200 can be received. The light receiving sensor 8 is a light receiving element that receives light from the light emitting unit 1 and outputs a signal, and a phototransistor, a photodiode, or the like can be used. An A / D conversion circuit 9 that converts an analog signal into a digital signal is connected to the light receiving sensor 8. A controller 4 is connected to the A / D conversion circuit 9. The A / D conversion circuit 9 digitally converts the detection value given by the light receiving sensor 8 and gives it to the control unit 4. The control unit 4 is configured to correct the target value of the drive current I supplied to each of the red LED 11, the green LED 12, and the blue LED 13 based on the given detection value. Since other configurations are the same as those of the second embodiment shown in FIG. 1, the same reference numerals as those in FIG. 1 are given to corresponding components, and detailed description of the configurations and operations is omitted.

  FIG. 9 is an explanatory diagram of a method for correcting the target value of the drive current I. The horizontal axis in FIG. 9 indicates the total use time t of the LED, and the vertical axis indicates the light quantity E of the LED. The change with time of the light amount E of the LED used in the illumination device 200 is indicated by a solid line, and the change with time of the light amount E of the reference LED is indicated by a one-dot chain line. Such a shift with respect to the light amount E may be caused by variations between lots of LEDs. As shown in FIG. 9, when the deviation (ΔE) occurs in the initial light quantity E1 (the part indicated by (1) in FIG. 9), the deviation related to the light quantity E shifts into the curve of the change over time of the light quantity E. May occur (portion indicated by (2) in FIG. 9). In the lighting device 200 according to the present embodiment, the light receiving sensor 8 detects the light amount E when the lighting device 100 starts to be used and is being used, and supplies a driving current to the light emitting unit 1 based on the detected light amount E. The target value of I is configured to be corrected.

  10 and 11 are flowcharts showing other processing procedures of the lighting control of the lighting device 200 of the control unit 4. After the lighting device 200 is turned on, the control unit 4 acquires a signal from the operation unit 7 and takes in setting information of light emission colors such as daylight white and light bulb color (step S11). Next, the total use time t of each of the red LED 11, green LED 12 and blue LED 13 stored in the memory 5 is read (step S12), and each of the red LED 11, green LED 12 and blue LED 13 stored in the memory 5 is read. The target value of the drive current I to be supplied is read (step S13). At the start of use of the lighting device 100, the drive current I is the initial drive current I1.

  Based on the emission color setting information fetched in step S11, the RGB ratio, which is the emission ratio of the red LED 11, green LED 12, and blue LED 13, stored in the memory 5 is read (step S14).

  The drive current I according to the target value of the drive current I of each LED 11, 12, 13 read in step S 13 and the set value such as the RGB ratio read in step S 14 is used as the red LED 11, green LED 12, and blue of the light emitting unit 1. The lighting device 200 is turned on by supplying to each of the LEDs 13 (step S15), and the timer 6 is started.

  Next, it is determined whether or not the total usage time t of the light emitting unit 1 is 0 (step S16). In step S16, if the total usage time t is 0, in other words, if the lighting device 200 is at the start of use (step S16: YES), the detection value of the initial light quantity is taken from the light receiving sensor 8 (step S17). . On the other hand, if the total use time t is not 0 in step S16 (step S16: NO), the process proceeds to step S21.

  It is determined whether or not there is a variation in the initial light amount using the detection value of the initial light amount captured in step S17 (step S18). The determination of the presence or absence of the variation in the initial light quantity is made based on whether or not ΔE shown in FIG. 9 is a predetermined value or more. In step S18, when there is variation in the initial light amount (step S18: YES), the target value of the drive current I supplied to the light emitting unit 1 is corrected (step S19). The correction for the initial deviation of the light amount E1 (part (1) in FIG. 9) is performed, for example, by multiplying the target value of the drive current I by E1 / (E1-ΔE). It is more preferable that the light quantity detection by the light receiving sensor 8 is performed by turning on the red LED 11, the green LED 12, and the blue LED 13 one by one in order.

  The drive current I according to the target value of the drive current I of each LED 11, 12, 13 corrected in step S 19 and the set value such as the RGB ratio read in step S 14 is used as the red LED 11, green LED 12 and blue color of the light emitting unit 1. The lighting device 200 is turned on by supplying each LED 13 (step S20).

  On the other hand, if there is no variation in the initial light amount in step S18 (step S18: NO), the process proceeds to step S21 without correcting the drive current.

  Based on the lighting time counted by the timer 6, the usage times of the red LED 11, the green LED 12 and the blue LED 13 are totaled to obtain the total usage time t (step S 21), and the total usage time t is stored in the memory 5. Remember.

  Next, using the total usage time t obtained in step S21, whether the total usage time t is a predetermined time ti (i = 1, 2, 3,...) Is determined for each of the red LED 11, the green LED 12, and the blue LED 13. (Step S22). In step S22, when the total usage time t is the predetermined time ti (step S22: YES), the drive current I is changed (step S23), the process proceeds to step S24, and the target value of the changed drive current I is set. Store in the memory 5. On the other hand, if the total use time t is not the predetermined time ti in step S22 (step S22: NO), the process proceeds to step S27 without changing the drive current I. The drive current I is changed by changing the drive current for each of the red LED 11, the green LED 12, and the blue LED 13 to the drive current I obtained by applying the total use time t of each LED 11, 12, 13 to the table. Is made by

  In step S24, the light intensity detection value for a predetermined time ti during use of the illumination device 200 is taken from the light receiving sensor 8 (step S24).

  Whether or not there is a variation in the amount of light, in other words, whether or not there is a deviation in the shape of the curve over time of the amount of light E, using the detected value of the amount of light at a predetermined time ti during use that is captured in step S24. Determination is made (step S25). The determination of whether or not there is a variation in the amount of light is made based on whether or not the deviation between the change curves with time indicated by the solid line and the alternate long and short dash line in FIG. In step S25, when there is a variation in the amount of light (step S25: YES), the target value of the drive current I supplied to the light emitting unit 1 is corrected (step S26). The correction for the deviation of the light amount E1 (part (2) in FIG. 9) is performed, for example, by multiplying the target value of the drive current I by a predetermined value determined according to the deviation.

  On the other hand, if there is no variation in the amount of light in step S25 (step S25: NO), the process proceeds to step S27 without correcting the drive current.

  In step S27, it is determined whether or not there is a change in emission color. This determination is made based on whether or not there is an input to the emission color setting information from the operation unit 7.

  In step S27, if there is a change in the emission color (step S27: YES), the process returns to step S14 and the series of operations is repeated until the power is shut off. On the other hand, if the emission color is not changed in step S27 (step S27: NO), the process returns to step S20 and the series of operations is repeated until the power is shut off.

  In the illuminating device 200 according to Embodiment 2 configured as described above, the light receiving sensor 8 detects the light amounts E of the red LED 11, the green LED 12, and the blue LED 13 of the light emitting unit 1, and the detected light amount E is obtained. Based on this, the target value of the drive current I supplied to each of the red LED 11, the green LED 12, and the blue LED 13 of the light emitting unit 1 is corrected. As described above, since the actual light amount E of each of the red LED 11, the green LED 12, and the blue LED 13 of the light emitting unit 1 is detected at the start of use and during the use of the lighting device 200, the initial light amount between the lots of LEDs is detected. Variations and variations with time can be corrected.

(Embodiment 3)
In the lighting device according to Embodiments 1 and 2, different tables indicating the relationship between the total use time t and the drive current I are used for each of the red LED 11, the green LED 12, and the blue LED 13 of the light emitting unit 1. However, the drive currents of the LEDs 11, 12, 13 may be set so that the temporal changes in the light amounts of the red LED 11, the green LED 12, and the blue LED 13 are the same.

  FIG. 12 is an explanatory diagram of setting of the drive current I in the third embodiment. 12A to 12D, the horizontal axis indicates the total usage time t of the LEDs 11, 12, and 13, and the vertical axis indicates the light amount E of the LEDs 11, 12, and 13, respectively. 12A shows the change over time of the light amount of the red LED 11, FIG. 12B shows the change over time of the amount of light of the green LED 12, FIG. 12C shows the change over time of the light amount of the blue LED 13, and FIG. d) is a diagram showing a change with time of the light amount E of the LED with respect to the drive current I;

  As shown in FIGS. 12A, 12B, and 12C, the initial drive currents I1 of the LEDs 11, 12, and 13 are set so that the temporal changes in the light amounts E of the red LED 11, the green LED 12, and the blue LED 13 are the same. It is. As a result, one diagram showing the change with time of the light amount E of the LED with respect to the drive current shown in FIG. 12D can be used in common for the red LED 11, the green LED 12 and the blue LED 13.

  In the lighting device configured as described above, the change in the light amount E with respect to the total use time t is supplied to each of the red LED 11, the green LED 12, and the blue LED 13 so as to be substantially the same among the red LED 11, the green LED 12, and the blue LED 13. The drive current I to be determined is determined. Since the change in the light amount E with respect to the total use time t of the red LED 11, the green LED 12, and the blue LED 13 is substantially the same, the total use time t for changing the drive current I and the change rate of the drive current I can be made the same. With a simple control configuration, the light color can be kept substantially the same, and the light amount can be kept substantially constant.

  In the above embodiment, the drive current is changed according to the total usage time for each of the red LED 11, the green LED 12, and the blue LED 13, which are a plurality of light sources. The drive current of at least one of the light sources may be configured to be changed according to the total use time of the light source. As a light source to be changed according to the total use time, for example, by selecting a light source that degrades most rapidly with the total use time, that is, a blue LED, it is possible to effectively suppress changes in light color and light amount with a simple configuration. It becomes possible.

  Moreover, although the above embodiment demonstrated the illuminating device provided with red LED11, green LED12, and blue LED13 as a some light source as an example, it is not limited to this. The present invention can be similarly applied to a lighting device including a light source having two or four or more different emission colors. Even in this case, the effects described above can be obtained.

  Moreover, the method for changing the drive current according to the total use time according to the present invention is also effective in an illumination device including only one type of light source. For example, in an illuminating device including a pseudo white LED having a blue LED and a yellow phosphor excited by light from the blue LED, a predetermined amount of light can be obtained by changing the drive current according to the total usage time. It is possible to lengthen the time during which the amount of light (for example, 70% of the initial amount of light) can be obtained, that is, to extend the life of the lighting device.

  In the above embodiment, the table showing the relationship between the total use time t of the red LED 11, the green LED 12, and the blue LED 13 of the light emitting unit 1 and the drive current I is used. The current may be expressed by a function having the total use time as a variable, and the drive current may be obtained by this function.

  In the above embodiment, an LED is used as a light source. However, the present invention is not limited to this, and EL (Electro Luminescence) or the like may be used.

  Further, as a lighting device according to the present invention, a downlight that is embedded in a mounting member such as a ceiling and that illuminates directly below, a spotlight that is rotatably provided and illuminates a narrow range in an arbitrary direction, and a ceiling Various illumination devices such as a so-called ceiling light that illuminates the entire room, a light bulb type illumination device that is attached to a socket for a light bulb, and a stand light that illuminates the user's hand can be assumed. In the above embodiments, the lighting device has been described as an example. However, the present invention is not limited to the lighting device, and can be applied to a light emitting device including a light emitting unit such as a backlight of a liquid crystal image device. Needless to say, various modifications can be made within the scope of the matters described in the claims.

1 Light-emitting part 11 Red LED
12 Green LED
13 Blue LED
4 Control unit (control means)
8 Light receiving sensor (light intensity sensor)
100,200 Illumination device (light emitting device)

Claims (8)

In a light emitting device comprising a light emitting unit and a control means for controlling a drive current for driving the light emitting unit,
The light-emitting device, wherein the control means is configured to change a drive current supplied to the light-emitting unit according to a total usage time of the light-emitting unit in order to obtain a predetermined light amount. Means for accumulating the usage time of the light emitting unit to obtain a total usage time, and a table showing the relationship between the total usage time of the light emitting unit and the drive current,
The control unit is configured to apply a total usage time of the light emitting unit obtained by the unit to the table to obtain a driving current, and to change the driving current supplied to the light emitting unit to the obtained driving current. The light-emitting device according to claim 1. The light emitting unit includes a plurality of light sources having different emission colors,
The light emission according to claim 1, wherein the control unit is configured to change a driving current of at least one light source among the plurality of light sources in accordance with a total use time of the light source. apparatus.   4. The light emitting device according to claim 3, wherein the drive current supplied to each of the plurality of light sources is determined such that a change in light amount with respect to a total use time is substantially the same between the plurality of light sources. A light amount sensor for detecting the light amount of the light emitting unit;
5. The control unit according to claim 1, wherein the control unit is configured to correct a target value of a drive current supplied to the light emitting unit based on a detection value by the light amount sensor. The light emitting device according to 1.   6. The light emitting device according to claim 1, wherein the light emitting unit includes an LED.   An illumination device comprising the light-emitting device according to any one of claims 1 to 6 and configured to emit light from the light-emitting device as illumination light. It is a drive method of the illuminating device of Claim 7, Comprising:
A life curve indicating a change in light amount with respect to the total usage time of the light emitting unit is obtained in advance using the drive current as a parameter, and is supplied to the light emitting unit based on the obtained life curve so that the light amount of the light emitting unit is substantially constant. A driving method of an illuminating device, wherein a driving current is determined according to a total usage time, and the determined driving current is supplied to the light emitting unit to drive the light emitting unit.

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