JP2017126483A - Led lighting device and led illumination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LED lighting device capable of performing high-accuracy initial illuminance correction control.SOLUTION: An LED lighting device (1) comprises DC power supply circuits (20, 40) for supplying a DC output to an LED (2) according to a dimming rate indicated by a dimming command value, a temperature detection circuit (50) for detecting the temperature in the vicinity of the LED, an increase rate determination unit (61) for successively increasing or decreasing a dimming increase rate, which is the increase rate of the dimming rate per unit time, with respect to increase or decrease in the detection temperature detected by the temperature detection circuit, a time counter (68) for counting the lighting time of the LED, and a dimming rate determining unit (62) for determining a dimming command value on the basis of the dimming rate obtained from the dimming increasing rate and the lighting time.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an LED lighting device and an LED lighting device using the LED lighting device.

  In general, as a property of an LED, it is known that the luminous flux (the illuminance associated therewith) decreases as the cumulative lighting time increases. This is because as the lighting time of the LED increases, the lattice defects that contribute to light emission change, and the YAG phosphor that converts blue light into white light deteriorates, resulting in a decrease in light emission efficiency. . The LED lighting device may be provided with a so-called initial illuminance correction function in order to compensate for such a change in illuminance (see Patent Document 1). The initial illuminance correction function is a function of reducing the LED current from the rated current at the beginning of LED lighting, and increasing the LED current as the cumulative lighting time proceeds to approach the rated current. Thereby, a fixed illuminance is obtained regardless of the elapsed time of use from the beginning of LED lighting. In addition, the initial illuminance correction function prevents unnecessarily high lighting from being performed at the beginning of lighting, thereby realizing energy saving and extending the life of the LED.

  For example, Patent Document 1 discloses a configuration in which a lamp such as an LED includes an illuminance correction unit, and the illuminance correction unit includes a time measuring unit that measures the cumulative lighting time of the light emitting element and a memory that stores the cumulative lighting time. Is done. In the illuminance correction unit, the illuminance correction characteristic is set based on the light flux decay characteristic of the light emitting element. The illuminance correction characteristic represents the correspondence between the dimming ratio as the illuminance correction value and the cumulative lighting time, and is set so that the light output of the light emitting element remains constant even if the cumulative lighting time of the light emitting element increases. The The illuminance correction unit uses the illuminance correction characteristic and determines the dimming ratio of the light emitting element based on the cumulative lighting time of the light emitting element. The illuminance correction unit includes a temperature measurement unit that measures the ambient temperature of the lamp, and determines illuminance correction characteristics to be used according to the ambient temperature measured by the temperature measurement unit. More specifically, the illuminance correction unit determines the ambient temperature, selects a luminous flux degradation characteristic at a corresponding temperature from a plurality of luminous flux degradation characteristics for each temperature stored in advance in the memory, and selects the selected luminous flux degradation characteristic. And determining the dimming ratio corresponding to the cumulative lighting time of the lamp using the illuminance correction characteristic.

JP 2011-222320 A

  However, there is room for improvement with respect to the accuracy of the initial illuminance correction control in the configuration in which the illuminance correction characteristic is determined by selecting the one corresponding to the detected temperature from the plurality of luminous flux decay characteristics stored for each temperature, as shown below. There is.

  First, it is desired to improve the followability of the correction control for the detected temperature or the resolution. According to the configuration in which one illuminance correction characteristic is used for a long time or permanently, the difference between the actual temperature and the temperature at the time of determining the illuminance correction characteristic increases due to the subsequent temperature change, so that The followability of illumination correction can be reduced. Further, according to the configuration in which one illuminance correction characteristic for one temperature setting is selected from a plurality of illuminance correction characteristics for a plurality of temperature settings, the difference between the actual detected temperature and the applied set temperature (that is, the detected temperature and Due to the closest difference in set temperature), the resolution of illuminance correction with respect to the detected temperature is potentially low. Thus, the accuracy of illumination correction is reduced by such low followability or resolution.

  Second, it is desirable that the LED degradation rate be predicted or controlled more accurately. The above configuration performs illuminance correction based on the deterioration rate of the LED predicted from the ambient temperature of the LED. Here, although the ambient temperature of the LED and the deterioration of the LED have a certain correlation, the element temperature of the LED causes a more direct deterioration, so the LED element temperature is more accurately reflected in the illuminance correction. Then, the deterioration rate of the LED should be accurately predicted or controlled, and highly accurate initial illumination correction control should be realized.

  Therefore, the present invention enables high-precision initial illuminance correction control by addressing at least one of the following problems of followability or resolution of the illuminance correction control or the problem of reflecting the LED element temperature in the illuminance correction control. It is an object to provide an LED lighting device and an LED lighting device using the LED lighting device.

  An LED lighting device according to a first embodiment of the present invention includes a DC power supply circuit that supplies a DC output to an LED according to a dimming rate indicated by a dimming command value, a temperature detection circuit that detects a temperature in the vicinity of the LED, and a temperature detection An increase rate determining unit that sequentially increases or decreases a dimming rate, which is a rate of increase of the dimming rate per unit time, with respect to an increase or decrease in the detected temperature detected by the circuit, and an LED lighting time And a dimming rate determination unit that determines a dimming command value based on the dimming rate obtained from the dimming rate and the lighting time.

  According to the first aspect, the increase rate determination unit sequentially increases or decreases the dimming increase rate with respect to the increase or decrease of the detected temperature, and determines the dimming rate based on the dimming increase rate and the lighting time. Since the unit determines the dimming command value, illuminance correction control having high followability with respect to the detected temperature is realized. Thereby, highly accurate initial illuminance correction control can be performed.

  Here, as one aspect, the dimming increase rate is configured to continuously increase or decrease with an increase or decrease in the detected temperature. Thereby, illuminance correction control with high resolution with respect to the detected temperature is obtained.

  In the LED lighting device of the second mode, in the first mode, the voltage detection circuit for detecting the forward voltage of the LED and the dimming increase rate are increased when the forward voltage is relatively high. When the directional voltage is relatively low, a correction processing unit for reducing the dimming increase rate is further provided.

  According to the second embodiment, the forward voltage is high / low, that is, the LED power is high / low, and the dimming rate is high / low. A relatively fast increase in illuminance is applied, and a relatively slow increase in illuminance is applied to an LED that generates little heat and can be degraded slowly. Thus, in addition to the advantageous effects obtained in the first embodiment, highly accurate initial illumination correction control that more accurately reflects the element temperature of the LED is realized.

  Further, the correction processing unit may be configured to decrease the dimming rate when the forward voltage is relatively high and to increase the dimming rate when the forward voltage is relatively low. Thereby, since low / high dimming rate corresponds to high / low forward voltage, the heat generation and deterioration rate of the LED are optimized. Moreover, the variation in LED power among LEDs fed from a plurality of LED lighting devices, that is, the variation in illuminance is eliminated.

  An LED lighting device according to a third aspect includes a DC power supply circuit that supplies a DC output to an LED according to a dimming rate indicated by a dimming command value, a temperature detection circuit that detects a temperature in the vicinity of the LED, and a forward voltage of the LED A correction function determining unit that determines a correction function that defines a change in dimming rate with respect to the cumulative lighting time of the LED according to the detected temperature detected by the temperature detection circuit, and cumulative lighting of the LED Determined by a lighting time acquisition unit that acquires time, a dimming rate determination unit that determines a dimming command value based on a dimming rate obtained by applying the cumulative lighting time to the correction function, and a correction function determination unit Regarding the dimming increase rate, which is the rate of increase of the dimming rate per unit time in the correction function, the dimming increase rate is increased when the forward voltage is relatively high, and the dimming increase rate is relatively low. Is the dimming rate Do not and a correction processing unit for correcting the correction function.

  According to the third embodiment, even in a simple control configuration in which one correction function is selected from a plurality of correction functions, as in the second embodiment, for an LED that generates a large amount of heat and can be rapidly deteriorated. A relatively fast increase in illuminance is applied, and an increase in illuminance is relatively slow for LEDs that generate little heat and can be slowed down. Thereby, highly accurate initial illuminance correction control reflecting the element temperature of the LED more accurately is realized.

  Further, the correction processing unit corrects the correction function by decreasing the dimming rate when the forward voltage is relatively high and increasing the dimming rate when the forward voltage is relatively low. It may be configured. Thereby, since low / high dimming rate corresponds to high / low forward voltage, the heat generation and deterioration rate of the LED are optimized. Moreover, the variation in LED power among LEDs fed from a plurality of LED lighting devices, that is, the variation in illuminance is eliminated.

  The LED lighting device of the present invention includes the LED lighting device according to any one of the above and an LED. As described above, since the LED is turned on using the LED lighting device that executes the highly accurate initial illuminance correction control, it is possible to manage the life of the LED lighting device appropriately.

It is a block diagram of the LED lighting device and LED lighting device by a 1st embodiment. It is an example of the temperature detection circuit and illuminance correction circuit in 1st Embodiment. It is a figure explaining operation | movement of the LED lighting apparatus by the structure of FIG. It is an enlarged view explaining operation | movement of the LED lighting apparatus by the structure of FIG. It is a block diagram of the LED lighting device and LED lighting device by 2nd Embodiment. It is a figure explaining operation | movement of the LED lighting apparatus by 2nd Embodiment. It is a figure explaining the development example of operation | movement of the LED lighting apparatus by 2nd Embodiment. It is a block diagram of the LED lighting device and LED lighting device by 3rd Embodiment. It is a figure explaining operation | movement of the LED lighting apparatus by 3rd Embodiment. It is a figure explaining the development example of operation | movement of the LED lighting apparatus by 3rd Embodiment. It is a block diagram of the LED lighting device and LED lighting device by a modification.

<First Embodiment>
FIG. 1 shows a block diagram of an LED lighting device 1 and an LED lighting device 3 according to the first embodiment of the present invention. The LED lighting device 3 is configured by the LED lighting device 1 and the LED 2. The LED lighting device 1 is supplied with power from an AC power source AC such as a commercial power source and lights the LED 2. LED2 comprises the LED module provided with the some LED element connected in series or series-parallel.

  The LED lighting device 1 includes an input circuit 10, a DC / DC converter 20, an output detection circuit 30, a control circuit 40, a temperature detection circuit 50, and an illuminance correction circuit 60, and receives an AC input supplied from an AC power supply AC as a predetermined direct current. It converts into an output and supplies a direct current and a direct current voltage to LED2. The DC / DC converter 20 and the control circuit 40 are also collectively referred to as a DC power supply circuit.

  The input circuit 10 includes a diode bridge 11 and an input capacitor 12. The AC input voltage is full-wave rectified by the diode bridge 11, and a pulsating voltage appears at the input capacitor 12. Note that the input circuit 10 is not required when a DC voltage from a DC power source is input to the LED lighting device 1.

  The DC / DC converter 20 includes a switching element 21 (MOSFET), a transformer 22, a diode 23, and an output capacitor 24, and supplies DC power to the LED 2 by PWM driving of the switching element 21. In the present embodiment, the DC / DC converter 20 is an insulating flyback converter, and constitutes a so-called one-converter flyback circuit having a power factor improving function. The DC / DC converter 20 may be other types of converters such as a buck converter and a buck boost converter.

  Energy is accumulated by the primary winding of the transformer 22 during the ON period of the switching element 21, and the energy is charged to the output capacitor 24 from the secondary winding side of the transformer 22 via the diode 23 during the OFF period of the switching element 21. . The output power of the DC / DC converter 20 is determined by the on-duty (duty ratio) in the PWM control of the switching element 21, the turn ratio of the secondary winding to the primary winding, and the like. The switching element 21 is driven by a control IC 45 for switching control described later. In the following description, the low potential electrode side node of the input capacitor 12 is referred to as a primary side ground G1, and the low potential electrode side node of the output capacitor 24 is referred to as a secondary side ground G2. The output current of the DC / DC converter 20 is simply referred to as “output current”, and the output voltage of the DC / DC converter 20 is simply referred to as “output voltage”. In each embodiment, the output current is equal to the LED current, and the output voltage is equal to the forward voltage Vf of LED2.

  The output detection circuit 30 includes a current detection circuit including a current detection resistor 31, and uses the secondary side ground G2 as a reference potential. The current detection resistor 31 is a low resistance element inserted between the secondary side ground G2 and the cathode end of the LED 2, and a voltage proportional to the output current is generated in the current detection resistor 31.

  The control circuit 40 includes an operational amplifier 41, a constant voltage source 42 (for example, a control power source), a resistor 43, a photocoupler 44, and a control IC 45, and performs constant current control on the output of the DC / DC converter 20. The photocoupler 44 includes a photodiode 44d and a phototransistor 44t, and the photodiode 44d and the preceding circuit (the operational amplifier 41, the constant voltage source 42, etc.) use the secondary side ground G2 as a reference potential, and the phototransistor 44t and the subsequent stage The circuit (control IC 45) operates using the primary side ground G1 as a reference potential. Note that a control power source is appropriately supplied to the control circuit 40.

  The detection current value from the output detection circuit 30 is input to the negative input terminal (−) of the operational amplifier 41, and the target current value from the illuminance correction circuit 60 is input to the positive input terminal (+) of the operational amplifier 41. . A feedback element (not shown) (resistor, capacitor, or a series circuit or a parallel circuit thereof) is connected between the negative input terminal and the output terminal of the operational amplifier 41, and an error between the negative input terminal voltage and the positive input terminal voltage is detected at the output terminal. Is output. The output of the operational amplifier 41 is connected to the cathode of the photodiode 44 d, and the anode of the photodiode 44 d is connected to the constant voltage source 42 via the resistor 43. In the photocoupler 44, the output state of the phototransistor 44t is determined according to the current flowing through the photodiode 44d, and the output of the phototransistor 44t is input to the control IC 45 as an input signal. During normal lighting, the operational amplifier 41 determines the ON width in the PWM control of the switching element 21 so that the output current (detected current value) matches the target current value.

  The control IC 45 includes a general LED driver IC, and peripheral circuit elements (not shown) are appropriately connected to the control IC 45. The control IC 45 generates a PWM drive signal having a pulse width corresponding to the output state of the phototransistor 44 t and outputs it as the gate voltage of the switching element 21. For example, the control IC 45 decreases / increases the on width of the PWM control and decreases the output current with respect to the increase / decrease of the current of the photodiode 44d and the phototransistor 44t. That is, the control circuit 40 performs constant current control on the DC / DC converter 20 so that the output current matches the target current value.

  The temperature detection circuit 50 is disposed in the vicinity of the LED 2, detects the ambient temperature or the ambient temperature of the LED 2, and converts the detected temperature into an electrical signal. The temperature detection circuit 50 constitutes a part of the LED lighting device 1 on the circuit, but is not inside the housing of the LED lighting device 1 but on the inside or outside of the housing in which the module of the LED 2 is housed. Preferably they are arranged. In other words, the temperature detection circuit 50 is outside the housing of the LED lighting device 1 and inside or outside the housing of the LED lighting device 3. The ambient temperature or the ambient temperature of the LED 2 is the ambient temperature of the casing in which the LED module that constitutes the LED 2 is housed. The temperature detection circuit 50 includes a series circuit of a resistor 51 and a PTC thermistor 52 connected in parallel to the LED 2.

  In this example, the voltage of the PTC thermistor 52, that is, the high / low of the temperature detection value of the temperature detection circuit 50 corresponds to the high / low of the detection temperature. The temperature detection value detected by the temperature detection circuit 50 is output to the illuminance correction circuit 60. Note that the temperature detection circuit 50 may be configured such that the logic of the detected temperature level and the detected temperature level of the temperature detection circuit 50 are reversed. If possible on the wiring, the temperature detection circuit 50 may be connected between the control power supply and the secondary side ground G2. In this case, since the detection value of the temperature detection circuit 50 is not affected by the output voltage, variations or fluctuations in the forward voltage Vf of the LED 2 (including variations due to abnormalities such as partial short circuit of the LED element) do not affect the temperature detection value. .

  The illuminance correction circuit 60 includes, for example, a microcomputer, and executes an initial illuminance correction function for increasing the dimming rate and the dimming command value in a predetermined manner according to the lighting time. The illuminance correction circuit 60 includes an increase rate determination unit 61, a dimming rate determination unit 62, an A / D conversion unit 66, a storage unit 67, and a timing unit 68. These units exchange signals or data with each other via a bus B. Are connected in a possible manner. The increase rate determination unit 61 and the dimming rate determination unit 62 constitute a part of the CPU, and the CPU can appropriately execute general processing functions not included in the above-described units. The A / D converter 66 performs A / D conversion on the voltage corresponding to the detected temperature detected by the temperature detection circuit 50 and takes it into the microcomputer. The A / D converter 66 may be outside the microcomputer. The storage unit 67 is a non-volatile memory for storing data and programs, and the timer unit 68 includes a timer or a counter.

  The increase rate determination unit 61 sequentially increases / decreases the dimming increase rate, which is the increase rate of the dimming rate per unit time, with respect to the increase / decrease of the detected temperature detected by the temperature detection circuit 50. That is, when the ambient temperature of the LED 2 is relatively high, the deterioration of the LED 2 (that is, the light flux decreasing speed) becomes relatively fast, and thus the increase rate determination unit 61 increases the dimming rate increase rate. Conversely, when the ambient temperature of the LED 2 is relatively low, the deterioration of the LED 2 (that is, the luminous flux decrease rate) is relatively slow, and thus the increase rate determination unit 61 reduces the dimming rate increase rate. . For example, even in the same LED lighting device 3, the dimming increase rate increases in the summer, and the dimming increase rate decreases in the winter. Alternatively, the dimming increase rate is relatively high in the LED lighting device 3 installed in a warm region, and the dimming increase rate is relatively low in the LED lighting device 3 installed in a cold region.

  The dimming rate determination unit 62 determines the dimming rate according to the dimming increase rate determined by the increase rate determination unit 61 and the lighting time measured by the timer unit 68. That is, when it is the first dimming rate at the first time, the second dimming rate at the second time after the unit time has elapsed from the first time is the unit of the determined dimming increase rate. A value obtained by adding the value multiplied by time to the first dimming rate is obtained. The dimming rate is determined so that the upper limit is 100% for all-light lighting. Then, the dimming rate determination unit 62 converts the determined dimming rate into a target current value that is a dimming command value, and outputs it to the operational amplifier 41 of the control circuit 40.

  FIG. 1 shows a configuration in which the detected temperature is input as an analog value to the increase rate determination unit 61 via the A / D conversion unit 66. Thereby, it is possible to perform initial illuminance correction control in which the continuous light control rate is determined with respect to the detected temperature, and the resolution of the initial illuminance correction is improved. On the other hand, the detected temperature may be input to the increase rate determining unit 61 as a binary signal. In this case, the A / D conversion unit 66 may be omitted, and the configuration can be simplified. FIG. 2 shows an exemplary temperature detection circuit 50 and illuminance correction circuit 60 when the detected temperature is given as a binary signal as described above.

  As shown in FIG. 2, the temperature detection circuit 50 includes a resistor 51, a PTC thermistor 52, and a switching element 53 such as a MOSFET. As described above, the temperature detection circuit 50 is preferably disposed on the module side of the LED 2 from the viewpoint of temperature detection accuracy. When the ambient temperature exceeds a predetermined temperature threshold (for example, 30 ° C.), the switching element 53 is turned on by the increased resistance value and voltage of the PTC thermistor 52, and the input value to the increase rate determination unit 61 is low (zero). Become. On the other hand, when the ambient temperature becomes equal to or lower than the temperature threshold, the switching element 53 is turned off by the decreased resistance value and voltage of the PTC thermistor 52, and the voltage source 54 (for example, control power supply) is connected to the increase rate determination unit 61 via the resistor 55. An input occurs and the input value goes high. It is assumed that the resistance value of the resistor 51 and the characteristics of the PTC thermistor 52 are selected so that the above switching is performed at a desired temperature threshold.

  In FIG. 3A, when the LED lighting device 1 (LED lighting device 3) employing the circuit of FIG. 2 is installed at a fixed point, a lighting state (dimming rate:%) and illuminance ( Or luminous flux). The horizontal axis represents the lighting time over the lifetime of the LED 2 (for example, 100,000 hours). FIG. 3B is a partially enlarged view of the graph of FIG. 3A. In each figure of this indication, a figure is a mimetic diagram and is not necessarily according to a size.

  As shown in FIG. 3A, the dimming rate starts at 80% and then increases, and after the dimming rate reaches 100%, the all-light lighting is maintained. Thereby, the illuminance becomes substantially constant over the lifetime. As shown in FIG. 3B (as seen slightly in FIG. 3A), the dimming increase rate is switched approximately periodically. That is, a high dimming rate A is applied in the summer when the ambient temperature exceeds the temperature threshold 30 ° C., and a low dimming rate B is applied in the winter when the ambient temperature is 30 ° C. or less. When the average lighting time per day throughout the year is about 10 hours, the cycle of a set of dimming rate A (summer) and dimming rate B (winter) is about 3650 hours.

  An example of setting the dimming increase rates A and B is as follows. The dimming increase rate A is a function set so that the initial illuminance correction is performed such that the illuminance becomes constant when the ambient temperature is constant at 35 ° C. For example, the dimming increase rate A is configured such that the dimming rate reaches 100% when the cumulative lighting time reaches 40000 hours if the dimming increase rate A is fixed and applied. On the other hand, the dimming increase rate B is a function set so that the initial illuminance correction in which the illuminance becomes constant when the ambient temperature is constant at 25 ° C. is executed. For example, the dimming increase rate B is configured such that the dimming rate reaches 100% when the cumulative lighting time reaches 60000 hours if the dimming increase rate B is fixed and applied. Thereby, as a result of the initial illuminance correction control shown in FIG. 3B, as shown in FIG. 3A, dimming is performed at any time (approximately 50000 hours in FIG. 3A) that is longer than 40000 hours and less than 60000 hours. The rate reaches 100%.

  In any of the configurations of FIGS. 1 and 2, a default dimming increase rate may be applied at the first lighting. Further, after the dimming rate reaches 100%, the increase rate determination unit 61 does not determine the dimming increase rate, and the dimming rate determination unit 62 determines the dimming command value (target current corresponding to all-lighting). Value) may be output to the control circuit 40.

  As described above, the LED lighting device 1 according to the present embodiment includes the DC power supply circuit (the DC / DC converter 20 and the control circuit 40) that supplies the DC output to the LED 2 according to the dimming rate indicated by the dimming command value, and the LED 2 A temperature detection circuit 50 for detecting the temperature in the vicinity and an illuminance correction circuit 60 are provided. In the illuminance correction circuit 60, the increase rate determination unit 61 sequentially increases / decreases the dimming increase rate with respect to the increase / decrease of the detected temperature detected by the temperature detection circuit 50, and the timer unit 68 turns on the LED 2 The time is measured, and the dimming rate determination unit 62 determines the dimming command value based on the dimming rate obtained from the dimming increase rate and the lighting time.

  In this way, the increase rate determination unit 61 sequentially increases / decreases the dimming increase rate with respect to the increase / decrease of the detected temperature, and the dimming rate determination unit 62 performs the increase / decrease based on the dimming increase rate and the lighting time. Since the dimming command value is determined, illuminance correction having high followability with respect to the detected temperature is realized. Further, when the dimming increase rate is continuously increased or decreased with respect to the increase or decrease of the detection temperature, illuminance correction with high resolution can be obtained with respect to the detection temperature. With this high followability or resolution, highly accurate initial illuminance correction control is realized. Moreover, since LED2 is lighted using LED lighting device 1 which performs highly accurate initial illumination correction control, appropriate lifetime management in LED lighting device 3 becomes possible.

<Second Embodiment>
In the first embodiment, the configuration in which the initial illuminance correction control depends on the ambient temperature is shown, but in the present embodiment, the configuration in which the initial illuminance correction control depends not only on the ambient temperature but also on the forward voltage Vf is shown. .

  FIG. 4 shows a block diagram of the LED lighting device 1 and the LED lighting device 3 according to the present embodiment. In the present embodiment, the same reference numerals are given to substantially the same configurations as those in the first embodiment (FIG. 1), and detailed description thereof will be omitted.

  In the present embodiment, the output detection circuit 30 further includes a voltage detection circuit including resistors 32 and 33 in addition to the current detection resistor 31. The voltage detection circuit (resistors 32 and 33) is a voltage dividing resistor circuit connected in parallel to the output capacitor 24, and a voltage proportional to the output voltage is generated in the resistor 33. The detection voltage detected by the voltage detection circuit, that is, the forward voltage Vf of the LED 2 is input to the A / D conversion unit 66 of the illuminance correction circuit 60.

  The illuminance correction circuit 60 further includes a correction processing unit 65 in addition to the increase rate determination unit 61, the dimming rate determination unit 62, the correction processing unit 65, the A / D conversion unit 66, the storage unit 67, and the time measuring unit 68. These parts are connected by a bus B in such a manner that signals or data can be exchanged with each other. Moreover, the increase rate determination part 61, the light control rate determination part 62, and the correction process part 65 comprise a part of CPU.

  The correction processing unit 65 increases the dimming increase rate when the forward voltage Vf of the LED 2 is relatively high with respect to the dimming increase rate determined by the increase rate determining unit 61, and the forward voltage Vf is relatively If it is too low, correction processing is performed so as to reduce the dimming rate. The dimming rate determination unit 62 determines the dimming rate according to the corrected dimming rate and lighting time, and outputs a target current value that is a dimming command value based on the dimming rate to the control circuit 40. The relationship between the level of dimming increase with respect to the level of forward voltage Vf is determined in advance in consideration of the deterioration characteristics of LED 2, variation in forward voltage Vf, and the like. The change may be gradual or continuous.

  More specifically, for the same LED current, the higher the forward voltage Vf, the higher the LED power, the higher the element temperature of the LED2, and the faster the LED2 deteriorates, while the lower the forward voltage Vf, The power is low, the element temperature of the LED 2 is low, and the deterioration of the LED 2 is delayed. Accordingly, the correction processing unit 65 increases the dimming rate relatively fast when the forward voltage Vf is relatively high, and relatively slow when the forward voltage Vf is relatively low. Increase. Thereby, the effect of the initial illuminance correction control is optimized.

  With reference to FIG. 5, operation | movement of the LED lighting device 1 is demonstrated with the illustration of a light control rate change. FIG. 5 shows changes in dimming rates C1, C2 and C3 in three LED lighting devices 1 installed in the same environment, where the vertical axis is the lighting state (dimming rate), and the horizontal axis is the cumulative lighting time. It is. It is assumed that the illuminance (light flux) corresponding to the change in each dimming rate is substantially constant. The dimming rates C1, C2, and C3 are dimming rates that are obtained as a result when the forward voltage Vf of the LED 2 connected to the LED lighting device 1 is Vf1, Vf2, and Vf3, respectively. Here, Vf1 <Vf2 <Vf3. As shown in the figure, the dimming increase rate as a result of the correction process is C1 <C2 <C3. That is, a relatively fast illuminance increase is applied to the LED 2 having a relatively high forward voltage Vf, and a relatively slow illuminance increase is applied to the LED 2 having a relatively low forward voltage Vf. .

  As described above, in the LED lighting device 1 of the present embodiment, the output detection circuit 30 includes the voltage detection circuit (resistors 32 and 33) that detects the forward voltage Vf of the LED 2, and the correction determination unit 65 includes the forward direction. When the voltage Vf is relatively high, the dimming increase rate is increased, and when the forward voltage Vf is relatively low, correction processing is performed so as to decrease the dimming increase rate. Accordingly, the forward voltage Vf is high / low, that is, the LED power is high / low, and the dimming increase rate is high / low. A fast increase in illuminance is applied, and a relatively slow increase in illuminance is applied to the LED 2 that generates a small amount of heat and can be degraded slowly. Thus, in addition to the advantageous effects obtained in the first embodiment, highly accurate initial illuminance correction control that more accurately reflects the element temperature of the LED 2 is realized.

<Development of Second Embodiment>
As a development example of the present embodiment, the correction processing unit 65 may further correct the dimming rate (the dimming command value) determined by the dimming rate determining unit 62. Specifically, the correction processing unit 65 decreases the dimming rate when the forward voltage Vf is relatively high, and increases the dimming rate when the forward voltage Vf is relatively low. The relationship between the level of the dimming rate (dimming command value) with respect to the level of the forward voltage Vf is predetermined in consideration of the deterioration characteristics of the LED 2 and variations in the forward voltage Vf, and the change in the forward voltage Vf. The change in the dimming rate with respect to may be stepwise or continuous.

  With reference to FIG. 6, operation | movement of the LED lighting device 1 is demonstrated with the illustration of a light control rate change. FIG. 6 shows dimming rates D1, D2 and D3 in the three LED lighting devices 1 installed in the same environment, the vertical axis is the lighting state (dimming rate), and the horizontal axis is the cumulative lighting time. . It is assumed that the illuminance (light flux) corresponding to the change in each dimming rate is substantially constant. The dimming rates D1, D2, and D3 are obtained as a result when the forward voltages Vf of the LEDs 2 connected to the LED lighting device 1 are Vf1, Vf2, and Vf3 (Vf1 <Vf2 <Vf3), respectively. Dimming rate. Since the forward voltage Vf appears as the above difference at the beginning of lighting, the correction processing by the correction processing unit 65 may be performed at the beginning of lighting (for example, at the first lighting).

  As a result of such correction processing, the dimming rate D1 is obtained by increasing the initial dimming rate of the dimming rate D2, and the dimming rate D3 is obtained by reducing the initial dimming rate of the dimming rate D2. Become. In other words, the dimming rate D1 is obtained by increasing the dimming rate C1 in FIG. 5 as a whole, and the dimming rate D3 is obtained by reducing the dimming rate C3 in FIG. 5 as a whole. As a result, a relatively low dimming rate and a fast increase in illuminance are applied to the LED 2 having a relatively high forward voltage Vf, and relatively to an LED 2 having a relatively low forward voltage Vf. A high dimming rate and a slow illuminance increase are applied.

  In the second embodiment and its development example, the dimming rate correction process or the dimming rate (dimming command value) correction process performed by the correction processing unit 65 is performed before the dimming rate reaches 100%. If it is a period, you may perform at any time not only in the lighting initial stage. This takes into consideration that the forward voltage Vf can be varied with time and that the forward voltage Vf can be reduced by a partial short-circuit failure of the LED elements constituting the LED 2. As a result, if the dimming rate is corrected as described above, the correction processing unit 65 may correct the dimming rate or the dimming command value.

  As described above, in the LED lighting device 1 of this example, the correction processing unit 65 reduces the dimming rate when the forward voltage Vf is relatively high, and the forward voltage Vf is relatively low. To increase the dimming rate. Thereby, the low / high dimming rate corresponds to the high / low forward voltage Vf, so that the heat generation and deterioration rate of the LED 2 are optimized. Moreover, the effect of eliminating the variation in LED power between the LEDs 2 fed from the plurality of LED lighting devices 1, that is, the variation in illuminance can also be obtained.

<Third Embodiment>
In the second embodiment, the configuration in which the dimming increase rate is sequentially determined as a premise of the configuration in which the initial illuminance correction control is performed based on the lighting time and the forward voltage Vf is shown. In the present embodiment, a configuration in which the initial illumination correction control is performed based on the lighting time and the forward voltage Vf in a configuration in which the dimming increase rate is determined in advance is shown.

  FIG. 7 shows a block diagram of the LED lighting device 1 and the LED lighting device 3 according to the present embodiment. In the present embodiment, components substantially the same as those of the second embodiment (FIG. 4) are denoted by the same reference numerals, and detailed description thereof is omitted.

  The illuminance correction circuit 60 includes a dimming rate determination unit 62, a correction function determination unit 63, a lighting time acquisition unit 64, a correction processing unit 65, an A / D conversion unit 66, a storage unit 67, and a timer unit 68. Are connected by a bus B in such a manner that signals or data can be exchanged with each other. Moreover, the light control rate determination part 62, the correction function determination part 63, the lighting time acquisition part 64, and the correction process part 65 comprise some CPUs. Note that the configuration shown in FIG. 2 may be employed as the temperature detection circuit 50 and the illuminance correction circuit 60.

  The storage unit 67 stores a plurality of correction functions that define changes in the dimming command value (target current value) indicating the dimming rate with respect to the cumulative lighting time of the LED 2 for each ambient temperature. The correction function will be described later.

  The correction function determination unit 63 determines a correction function that defines the change in the dimming rate with respect to the cumulative lighting time as described above, for example, based on the ambient temperature during initial lighting. The correction function determination unit 63 selects one correction function from the plurality of correction functions stored in the storage unit 67 according to the ambient temperature. More specifically, the correction function determination unit 63 first performs initial lighting in a default setting correction function or lighting state (for example, dimming rate 80%), and has a value closest to the ambient temperature detected at the time of initial lighting. A correction function for the ambient temperature is then adopted. The initial lighting means lighting within a few times after the LED 2 is mounted on the LED lighting device 1, preferably the first lighting.

  The lighting time acquisition unit 64 acquires the cumulative lighting time of the LED 2. The cumulative lighting time is acquired from the time output from the time measuring unit 68 and stored in the storage unit 67. In the period after the dimming rate becomes constant at 100%, it is not necessary to acquire the cumulative lighting time.

  The dimming rate determination unit 62 determines the dimming rate by applying (substituting) the cumulative lighting time to the correction function determined by the correction function determining unit 63, and determines the dimming rate as a target current that is a dimming command value. The value is converted into a value and output to the operational amplifier 41 of the control circuit 40.

  The correction processing unit 65 acquires the forward voltage Vf detected by the voltage detection circuit (resistors 32 and 33) via the A / D conversion unit 66. When the forward voltage Vf is relatively high with respect to the dimming increase rate that is the rate of increase of the dimming rate per unit time in the correction function determined by the correction function determining unit 63, the correction determination unit 65 performs dimming when the forward voltage Vf is relatively high. When the forward rate Vf is relatively low, the correction function is corrected so as to decrease the dimming rate when the rate of increase is increased. The operation and effect of this correction processing are the same as those described in the second embodiment. That is, the correction processing unit 65 increases the dimming rate relatively fast when the forward voltage Vf is relatively high, and relatively slow when the forward voltage Vf is relatively low. By increasing the value, the effect of the initial illuminance correction control is optimized.

  With reference to FIG. 8, the operation of the LED lighting device 1 will be described together with an example of the correction function. In FIG. 8, correction functions E0 and F0 are correction functions corresponding to the standard value of the forward voltage Vf of the LED 2, the correction function E0 indicates a correction function for an ambient temperature of 35 ° C., and the correction function F0 is an ambient temperature of 25 ° C. The correction function for is shown. The horizontal axis is the cumulative lighting time. Both the correction functions E0 and F0 are turned on at a dimming rate of 80%. For example, for the correction function E0, the dimming rate is 100% when the cumulative lighting time is 40000 hours, and for the correction function F0, the dimming rate is 100% when the cumulative lighting time is 60000 hours. Is set in advance. Also in FIG. 8, it is assumed that the illuminance (light flux) corresponding to each correction function is substantially constant.

  When the forward voltage Vf is higher than the standard value by a predetermined amount, the correction processing unit 65 increases the dimming increase rate of the correction function E0 / F0 to change the correction function E0 / F0 to the correction function E1 / F1. Correct it. Further, when the forward voltage Vf is lower than the standard value by a predetermined amount, the correction processing unit 65 reduces the dimming increase rate of the correction function E0 / F0 and changes the correction function E0 / F0 to the correction function E2 / Correct to F2. Thereby, in each temperature zone, a relatively fast illuminance increase is applied to the LED 2 having a relatively high forward voltage Vf, and relatively slow to the LED 2 having a relatively low forward voltage Vf. Increased illumination is applied. The predetermined amount and the relationship between the predetermined amount and the amount of change in dimming rate are appropriately determined in consideration of the deterioration characteristics of the LED 2 and variations in the forward voltage Vf.

  In addition, although the correction function (E0-E2 and F0-F2) with respect to two atmospheric temperature (35 degreeC and 25 degreeC) is shown, the correction function with respect to three or more atmospheric temperatures may be prescribed | regulated. For example, for an ambient temperature of 15 ° C., a function that results in a dimming rate of 100% at a cumulative lighting time of 100,000 hours for a standard forward voltage Vf (that is, the dimming rate continues to increase over almost the entire life). May be defined. Further, the change between the correction functions with respect to the change in the forward voltage Vf (for example, the change between the correction functions E1 to E2 and the change between the correction functions F1 to F2) is continuous even if it is stepwise. Also good.

  As described above, the LED lighting device 1 according to the present embodiment includes a DC power supply circuit (DC / DC converter 20 and control circuit 40) that supplies a DC output to the LED 2 according to the dimming rate indicated by the dimming command value, and the vicinity of the LED. A temperature detection circuit 50 for detecting the temperature of the LED 2, a voltage detection circuit (resistors 32 and 33) for detecting the forward voltage Vf of the LED 2, and an illuminance correction circuit 60. In the illuminance correction circuit 60, the correction function determination unit 63 determines a correction function that defines a change in the dimming rate with respect to the cumulative lighting time according to the detected temperature, and the lighting time acquisition unit 64 acquires the cumulative lighting time of the LED. The dimming rate determination unit 62 determines the dimming command value based on the dimming rate obtained by applying the cumulative lighting time to the correction function. The correction processing unit 65 corrects the dimming increase rate to increase when the forward voltage Vf is relatively high, and to decrease the dimming increase rate when the forward voltage Vf is relatively low. Modify the function.

  As described above, even in a simple control configuration in which one correction function is selected from a plurality of correction functions, as in the second embodiment, the heat generation is large and the LED 2 can be deteriorated relatively quickly. A fast increase in illuminance is applied, and a relatively slow increase in illuminance is applied to the LED 2 that generates a small amount of heat and can be degraded slowly. Thereby, highly accurate initial illuminance correction control reflecting the element temperature of the LED 2 more accurately is realized.

<Development of Third Embodiment>
As a development example of the present embodiment, the correction processing unit 65 may further correct the correction function determined by the correction function determination unit 63. Specifically, the correction processing unit 65 reduces the dimming rate (the dimming command value) when the forward voltage Vf is relatively high, and adjusts the light when the forward voltage Vf is relatively low. The correction function is further modified by increasing the rate (dimming command value).

  With reference to FIG. 9, the operation of the LED lighting device 1 will be described together with an example of the correction function. The correction functions E0 and F0 are the same as those shown in FIG. 8, and the correction functions E0 and F0 are correction functions corresponding to the standard values of the forward voltage Vf at the atmospheric temperature of 35 ° C. and 25 ° C., respectively. The horizontal axis is the cumulative lighting time. Also in FIG. 9, the illuminance (light flux) corresponding to each correction function is assumed to be substantially constant.

  The correction processing unit 65 reduces the initial dimming rate of the correction function E0 / F0 and reduces the correction function E0 / F0 to the correction function E3 when the forward voltage Vf is higher than the standard value by a predetermined amount at the initial lighting. Correct to / F3. On the other hand, the correction processing unit 65 corrects the correction function E0 / F0 by increasing the initial dimming rate of the correction function E0 / F0 when the forward voltage Vf is lower than the standard value by a predetermined amount during initial lighting. Modify to function E4 / F4. Thereby, in each temperature range, a fast illuminance increase is applied at a relatively low dimming rate to the LED 2 having a relatively high forward voltage Vf, and to the LED 2 having a relatively low forward voltage Vf. A relatively high dimming rate and a slow illuminance increase are applied. The predetermined amount and the relationship between the predetermined amount and the dimming rate change amount are appropriately determined in consideration of the deterioration characteristics of the LED 2 and variations in the forward voltage Vf. As a result, if the dimming rate is corrected as described above, the correction processing unit 65 may correct the dimming rate or the dimming command value.

  Moreover, although the correction function (E0-E4 and F0-F4) with respect to two atmospheric temperature (35 degreeC and 25 degreeC) is shown, the correction function with respect to three or more atmospheric temperatures may be prescribed | regulated. For example, for an ambient temperature of 15 ° C., a function that provides a dimming rate of 100% after a cumulative lighting time of 100,000 hours for a standard forward voltage Vf may be defined. Further, the change between the correction functions with respect to the change in the forward voltage Vf (for example, the change between the correction functions E3 to E4 and between the correction functions F3 to F4) is continuous even if it is stepwise. Also good.

  As described above, the LED lighting device 1 of the present example decreases the dimming rate when the forward voltage Vf is relatively high, and increases the dimming rate when the forward voltage Vf is relatively low. To correct the correction function further. Thus, the low / high dimming rate corresponds to the high / low forward voltage Vf, so that the heat generation and deterioration rate of the LED 2 are optimized. Moreover, the effect of eliminating the variation in LED power between the LEDs 2 fed from the plurality of LED lighting devices 1, that is, the variation in illuminance can also be obtained.

<Modification>
Although preferred embodiments of the present invention have been described above, the present invention can be modified into various modes as shown below, for example.

(1) Modification of Correction Processing Unit 65 In each of the above embodiments, the dimming rate or the dimming command value is determined by the dimming rate determining unit 62 after the dimming rate increasing rate is determined by the increasing rate determining unit 61. The configuration in which correction processing for each value is performed by the correction processing unit 65 is shown later or after the correction function is determined by the correction function determination unit 63. On the other hand, the process of determining the dimming rate, the dimming ratio, the dimming command value, or the correction function, and the correction process for those values by the correction processing unit 65 may be performed substantially simultaneously.

(2) Modification of output current control In each of the above embodiments, the configuration in which current feedback is employed for output current control in the DC power supply circuit (DC / DC converter 20 and control circuit 40) has been described. A configuration in which feedforward is adopted for output current control is also possible. FIG. 10 shows a block diagram of the LED lighting device 1 and the LED lighting device 3 in this case. As shown in FIG. 10, in the control circuit 40, the dimming command value (target current value) from the illuminance correction circuit 60 is input to the photodiode 44 d via the amplifier circuit 46. The temperature detection circuit 50 and the illuminance correction circuit 60 are any of the temperature detection circuit 50 and the illuminance correction circuit 60 described above for the first to third embodiments (therefore, the detection circuit 30 (voltage detection circuit) is necessary). Provided). In this way, the control circuit 40 performs feedforward control of the output current of the DC / DC converter 20 according to the target current value determined by the illuminance correction circuit 60 based on the ambient temperature detected by the temperature detection circuit 50.

1 LED lighting device 2 LED
3 LED lighting device 20 DC / DC converter (DC power supply circuit)
30 Output detection circuit 32, 33 Resistance (voltage detection circuit)
40 Control circuit (DC power supply circuit)
DESCRIPTION OF SYMBOLS 50 Temperature detection circuit 60 Illuminance correction circuit 61 Ascent rate determination part 62 Dimming rate determination part 63 Correction function determination part 64 Lighting time acquisition part 65 Correction process part 68 Time measuring part

Claims (7)

An LED lighting device,
A DC power supply circuit that supplies a DC output to the LED according to the dimming rate indicated by the dimming command value;
A temperature detection circuit for detecting a temperature in the vicinity of the LED;
An increase rate determination unit that sequentially increases or decreases a dimming increase rate, which is an increase rate of the dimming rate per unit time, with respect to an increase or decrease in the detection temperature detected by the temperature detection circuit;
A timer for measuring the lighting time of the LED;
An LED lighting device comprising: a dimming rate determining unit that determines the dimming command value based on the dimming rate obtained from the dimming rate and the lighting time.   The LED lighting device according to claim 1, wherein the dimming increase rate is continuously increased or decreased with respect to an increase or decrease in the detected temperature. The LED lighting device according to claim 1 or 2,
A voltage detection circuit for detecting a forward voltage of the LED;
And a correction processing unit that increases the dimming increase rate when the forward voltage is relatively high, and reduces the dimming increase rate when the forward voltage is relatively low. Lighting device.   4. The LED lighting device according to claim 3, wherein the correction processing unit reduces the dimming rate when the forward voltage is relatively high, and the correction processing unit reduces the dimming rate when the forward voltage is relatively low. An LED lighting device configured to increase the dimming rate. An LED lighting device,
A DC power supply circuit that supplies a DC output to the LED according to the dimming rate indicated by the dimming command value;
A temperature detection circuit for detecting a temperature in the vicinity of the LED;
A voltage detection circuit for detecting a forward voltage of the LED;
A correction function determining unit that determines a correction function that defines a change in the dimming rate with respect to the cumulative lighting time of the LED according to a detected temperature detected by the temperature detection circuit;
A lighting time acquisition unit for acquiring a cumulative lighting time of the LED;
A dimming rate determining unit that determines the dimming command value based on a dimming rate obtained by applying the cumulative lighting time to the correction function;
The dimming increase rate, which is the rate of increase of the dimming rate per unit time in the correction function determined by the correction function determining unit, is increased when the forward voltage is relatively high. And a correction processing unit that corrects the correction function by reducing the dimming increase rate when the forward voltage is relatively low.   6. The LED lighting device according to claim 5, wherein the correction processing unit decreases the dimming rate when the forward voltage is relatively high, and the correction processing unit reduces the dimming rate when the forward voltage is relatively low. An LED lighting device configured to further modify the correction function by increasing a dimming rate. The lighting device provided with the LED lighting device as described in any one of Claim 1 to 6, and the said LED.

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