WO2022157917A1 - 光源装置 - Google Patents
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- WO2022157917A1 WO2022157917A1 PCT/JP2021/002208 JP2021002208W WO2022157917A1 WO 2022157917 A1 WO2022157917 A1 WO 2022157917A1 JP 2021002208 W JP2021002208 W JP 2021002208W WO 2022157917 A1 WO2022157917 A1 WO 2022157917A1
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/40—Details of LED load circuits
- H05B45/44—Details of LED load circuits with an active control inside an LED matrix
- H05B45/48—Details of LED load circuits with an active control inside an LED matrix having LEDs organised in strings and incorporating parallel shunting devices
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/10—Controlling the intensity of the light
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/30—Driver circuits
- H05B45/32—Pulse-control circuits
- H05B45/325—Pulse-width modulation [PWM]
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
- Y02B20/40—Control techniques providing energy savings, e.g. smart controller or presence detection
Definitions
- This application relates to a light source device.
- a light source device configured by combining an LED (light emitting diode) light source and a light source driving circuit for driving the LED light source is used as an automobile headlight.
- LED light sources are used as light sources for automobile headlights.
- the LED is lit by being supplied with current from the light source drive circuit.
- a plurality of LEDs are connected in series, a bypass switch is provided in parallel to each of the LED light sources connected in series, and this bypass switch is controlled to turn on and off, thereby dimming and partially extinguishing the LED light source. It is equipped with a function to realize various light distribution patterns.
- the equivalent number of LED light sources connected in series as seen from the light source drive circuit changes depending on the ON/OFF control state of the bypass switch.
- the light source driving circuit requires a total forward direction according to the number m of the equivalent LED light sources connected in series.
- a voltage m*Vf must be applied.
- Patent Document 1 a technology has been proposed for a lighting circuit and vehicle lamp that prevents the LED light source from turning off by controlling the bypass switch according to the VIN situation.
- the present application has been made in response to the above-described problems of the conventional technology, and even when at least two LED light sources among the plurality of series LED light sources are controlled with different lighting duty ratios, the light distribution pattern can be controlled. It is an object of the present invention to provide a light source device that prevents an LED light source from turning off due to a voltage drop without restricting power consumption.
- a light source device includes a power source device that receives an output of an external power source and outputs a voltage of a predetermined value, and a light source unit, wherein the light source unit includes a plurality of light sources connected in series and each of the light sources a switch connected in parallel to, a light source drive circuit that receives output power from the power supply device and supplies current to the configuration of the light source and the switch, and a switch control circuit that controls on and off of the switch, By turning on and off the switch, the plurality of light sources are dimmed according to the lighting duty ratio, the lighting duty ratios of at least two of the light sources are different from each other, and each of the light sources is arranged in order from the light source having the largest lighting duty ratio. It is characterized in that the light sources are turned on and turned off in order from the light source having the smallest lighting duty ratio.
- the light source device of the present application even when at least two of the plurality of light sources are controlled with different lighting duty ratios, stable lighting is achieved without restricting the light distribution pattern and preventing the light sources from being turned off due to a voltage drop. can be realized.
- FIG. 1 is a configuration diagram of a light source device according to Embodiment 1.
- FIG. 1 is a configuration diagram of a power supply device according to Embodiment 1;
- FIG. 2 is a configuration diagram of a light source driving circuit according to Embodiment 1.
- FIG. 4 is an explanatory diagram showing output states of switches and light sources in Embodiment 1.
- FIG. 8 is an explanatory diagram of control signals in a comparative example with respect to the first embodiment;
- FIG. 3 is an operation explanatory diagram of Embodiment 1;
- FIG. 11 is an operation explanatory diagram of the second embodiment;
- FIG. 10 is an explanatory diagram for a case where the lighting duty ratios of the second embodiment are different;
- FIG. 10 is an explanatory diagram showing a start time point of dimming control according to the second embodiment
- FIG. 11 is a configuration diagram of a light source device according to Embodiment 3
- FIG. 11 is an operation explanatory diagram of Embodiment 3
- FIG. 11 is an operation explanatory diagram of Embodiment 4
- FIG. 11 is an operation explanatory diagram of Embodiment 5
- FIG. 14 is an operation explanatory diagram of a second control example of the fifth embodiment
- FIG. 4 is an explanatory diagram of the gain-frequency characteristics of the open-loop transfer function of the power supply
- FIG. 11 is an operation explanatory diagram of Embodiment 6
- FIG. 21 is a first operation explanatory diagram of Embodiment 7
- FIG. 20 is a second operation explanatory diagram of Embodiment 7;
- FIG. 21 is a first operation explanatory diagram of the eighth embodiment;
- FIG. 20 is a second operation explanatory diagram of the eighth embodiment;
- 3 is a configuration diagram showing the hardware configuration of control means used in the embodiment;
- FIG. 1 is a configuration diagram showing the configuration of a light source device including a light source drive circuit that drives an LED light source. A case where the LED light source is used for the headlight of an automobile will be described below.
- a light source device 100 according to Embodiment 1 includes a power source device 2 that receives a voltage VIN1 of an input voltage source 1 (external power source) and outputs a predetermined voltage value, and light source control information.
- a switch control circuit 6 for controlling ON and OFF respectively
- a light source driving circuit 7 for supplying current to a plurality of LED light sources 4 with the output of the power supply device 2 as an input. It is configured as a light source unit 8 .
- the light source control information when the light source device is used for the headlights of a vehicle and an oncoming vehicle is detected by a camera, a sensor, or the like, a plurality of LED Control information for turning off only a specific LED light source among the light sources can be mentioned.
- the input voltage source 1 in Embodiment 1 is an automobile battery will be described as an example.
- An input voltage source 1 outputs a voltage VIN1.
- the power supply device 2 in Embodiment 1 is composed of a boost chopper illustrated in FIG.
- the main circuit of the boost chopper consists of an inductor 21 (L), a diode 22 (D) and a switching element 23 (Q).
- the switching element 23 (Q) is exemplified by a MOSFET (Metal Oxide Semiconductor Field Effect Transistor).
- MOSFET Metal Oxide Semiconductor Field Effect Transistor
- the switching element 23 may be a TRANSISTOR, an IGBT (Insulated Gate Bipolar Transistor), or the like.
- the asynchronous rectification type is illustrated in FIG. 2, a synchronous rectification type may be used.
- the boost chopper shown in FIG. 2 receives a pulse modulation signal (PWM2) such as PWM (Pulse Width Modulation) output from a boost controller 24 via a gate driver 25 (GD) to a switching element 23 (Q). input to the gate terminal to control switching.
- PWM2 pulse modulation signal
- the output voltage value Vo2 of the boost chopper is monitored by the output voltage monitor circuit 26, and the voltage monitor signal VoM2 is fed back to the boost controller 24.
- the boost controller 24 adjusts the duty ratio of the pulse modulation signal PWM2 so that the output voltage value Vo2 of the boost chopper approaches the target voltage value based on the difference value between the predetermined output voltage target value VT2 and the voltage monitor signal VoM2. Control.
- the input voltage VIN1 input to the boost chopper is output from the power supply device 2 as an output voltage value Vo2 equal to or higher than VIN1 according to the output voltage target value VT2.
- FIG. 2 illustrates a voltage mode boost chopper that monitors only the output voltage value Vo2 and controls the switching element 23(Q), the inductor 21(L) and the switching element 23(Q)
- a peak current mode system or an average current mode system in which the switching element 23 (Q) is controlled by simultaneously monitoring the current flowing through the circuit or the like may also be used.
- the power supply device 2 in Embodiment 1 is not limited to a boost chopper, and may be any constant voltage output source having a boost function.
- it may be a buck-boost chopper, a flyback converter, an H-type buck-boost converter, a SEPIC (Single-Ended Primary-Inductance Converter), or the like.
- the light source drive circuit 7 in Embodiment 1 is configured with a step-down chopper illustrated in FIG.
- the main circuit of the step-down chopper is composed of switching element 71 (Q), diode 72 (D), inductor 73 (L) and capacitor 74 (C).
- the switching element 71 (Q) is not limited to MOSFET, and may be TRANSISTOR, IGBT, or the like.
- the step-down chopper may be of a synchronous rectification type.
- the step-down chopper illustrated in FIG. 3 inputs a pulse modulated signal PWM7 such as PWM output from a step-down controller 75 to a gate terminal of a switching element 71 (Q) via a gate driver 76 (GD). and perform switching control.
- the output current Io7 of the step-down chopper depends on the ON/OFF control state of each of the switches 5 (5-1 to 5-m), which is the load LED light source 4 (4-1 to 4-m) or the switch 5 ( 5-1 to 5-m), the current is monitored by the output current monitor circuit 77, and the current monitor signal IoM7 is fed back to the step-down controller 75.
- FIG. Note that the location of the output current monitor circuit 77 is not limited to that illustrated in FIG. Any place where Io7 can be monitored may be used.
- the step-down controller 75 adjusts the duty ratio of the pulse modulation signal PWM7 so that the output current Io2 of the step-down chopper approaches the target current value based on the difference value between the predetermined output current target value IT7 and the current monitor signal IoM7. It controls the output voltage Vo7 of the step-down chopper.
- the step-down chopper that is, the light source driving circuit 7, based on the output voltage value Vo2 of the power supply device 2, according to the output current target value IT7, the LED light source 4 (4-1 to 4-m) which is the load. and outputs a constant current Io7 to the switches 5 (5-1 to 5-m).
- the control signals PWM (5-1 to 5-m) are signals for controlling the ON/OFF of the switches 5 (5-1 to 5-m), respectively. It is assumed that the switch is turned on at HIGH level (hereinafter referred to as H level). As in the example shown in state 1 in FIG. 4, when the switches 5 (5-1 to 5-m) are off (PWM5-m is L level), the constant current Io7 output from the light source drive circuit 7 is the LED light source. 4 (4-1 to 4-m), the LED light source 4 (4-1 to 4-m) is lit.
- the LED light source 4-1, the switch 5-1, the switch 5-2, and the switch 5-3 are controlled by each control of the switches 5 (5-1 to 5-m).
- a constant current Io7 flows.
- the LED light sources 4-1, 4-2, 4-3, 4- are controlled by the switches 5 (5-1 to 5-m). 4
- a constant current Io7 flows.
- FIG. 5 shows a comparative example in the case of the control signal PWM5-m.
- the light source drive circuit 7 receives the voltage directly from the input voltage source VIN1, that is, the battery for the automobile.
- each control signal PWM5-m has the same duty ratio.
- Embodiment 1 of the present application by providing the power supply device 2 described above, the input voltage source VIN1 is boosted, and when the number of LED light sources is m, the output voltage value Vo2 of the power supply device 2 is higher than m ⁇ Vf. By outputting a sufficiently high voltage, it is possible to prevent the LED light source from going out. However, if the output voltage value Vo2 of the power supply device 2 is made much higher than m ⁇ Vf, the efficiency will decrease, resulting in an increase in the size and cost of the circuit.
- the LED light source 4 (4-1 to 4-m) or the switch 5 (5-1 to 5-m), which is the load, is controlled by the light source driving circuit 7 according to the control state of each switch 5-m as described above.
- the number of equivalent LED light sources connected in series as viewed from 1 changes every moment. Therefore, it is necessary to consider wide variations in the amount of current output from the power supply device 2 .
- the power supply device 2 must consider a wide range of fluctuations in both the input voltage and the output current. It is difficult to increase the frequency (zero cross frequency of loop gain) FBW.
- the constant voltage control of the output voltage value Vo2 cannot keep up with fast load fluctuations, and there are cases where the output voltage value Vo2 falls below m ⁇ Vf. and stable lighting cannot be achieved.
- FIG. 6 is an explanatory diagram of a control example according to the first embodiment.
- the target voltage of the output voltage value Vo2 of the power supply device 2 is set to a voltage higher than 4 ⁇ Vf by several volts, and the output voltage value Vo2 and the voltage 4 ⁇ Vf required for the LED light source are relatively close to each other.
- the output voltage value Vo2 when all the LEDs are turned off is expressed as 0 ⁇ Vf for convenience. shall not be
- FIG. 6 illustrates a case where dimming control is started from a period in which the number of simultaneously lit LED light sources is the smallest in the dimming control cycle of the LED light source. Examples are not limiting.
- each of the four LED light sources 4 is turned on in descending order of lighting duty ratio, and turned off in ascending order of lighting duty ratio. According to such control, even when each LED is controlled with a different lighting duty ratio, the degree of freedom in designing the pattern of each lighting duty ratio is high, and design can be easily performed without restrictions. However, it is necessary to solve the problem of the response frequency band of the power supply device 2 and the problem of efficiency reduction due to high output voltage.
- the total number of lighting is 4 from the start of lighting of each LED light source where the total number of lighting is 1 to 3. It is possible to provide a time lag until the start of lighting of the light source, and to increase the amount of current output from the power supply device 2 step by step. Therefore, even when the FBW of the power supply device 2 is low and the output voltage value Vo2 is a voltage higher than 4 ⁇ Vf by several volts, the response frequency The minimum voltage value Vo2 (min) when the output voltage value Vo2 fluctuates can be maintained or restored to a state higher than 4 ⁇ Vf within the range of the band.
- the voltage value of the output voltage value Vo2 can be minimized to improve the efficiency of the power supply device 2, and the voltage drop due to the limitation of the response frequency band can be suppressed to turn off the lights. Prevented stable lighting can be realized.
- the time from the start of turning off each LED light source when the total number of lighting is 3 to 1 to the start of turning off the LED light source when the total number of lighting is 0. It is possible to provide a time difference between them, and to reduce the amount of current output from the power supply device 2 step by step. Therefore, even when the FBW of the power supply 2 is low, the maximum output voltage value Vo2(max) when the output voltage value Vo2 fluctuates can be minimized within the range of the response frequency band of the power supply 2 . Therefore, when the plurality of LED light sources are turned off, the efficiency of the power supply device 2 can be improved by setting the output voltage value Vo2 to the minimum required voltage value and by suppressing the maximum voltage when it fluctuates to a minimum.
- Embodiment 2 A second embodiment of the present application will be described.
- the reference numerals used in the description of the first embodiment are used for the elements whose action or function is the same as that of the first embodiment, and the detailed description of each element is appropriately omitted.
- the second embodiment starts the dimming control from the period when the number of simultaneous lighting of the LED light sources is the largest.
- FIG. 7 is an explanatory diagram of a control example according to the second embodiment.
- FIG. 7 shows that when the lighting duty ratios of the four LED light sources are set to 10%, 30%, 60%, and 80% as in the example of FIG. 6 of Embodiment 1, the lighting duty ratios are large.
- the LEDs are turned on in order from the lowest, and are turned off in order from the lowest lighting duty ratio, and the dimming control is started from the state in which the number of simultaneous lighting of the LED light sources is four in the dimming control cycle of the LED light sources. .
- the same effect as the example of FIG. 6 described above can be obtained.
- the unique effects of the second embodiment can be obtained.
- the lighting duty ratio of each LED light source is high, the time intervals between the lighting timings of the LED light sources and the time intervals between the lighting timings of the LED light sources become short.
- the degree of instantaneous voltage drop in the output voltage value Vo2 of the device 2 may increase.
- FIG. 9 illustrates an example of the start-up period up to the start point of the dimming control in FIGS. 7 and 8.
- the lighting duty ratio of each LED light source is 10%, 30%, 60%, and 80%
- the maximum simultaneous lighting number is four. Lighting control is performed for each LED light source in stages so that the light source is in a lighting state.
- Embodiment 3 A third embodiment of the present application will be described.
- a plurality of light source units 8-N are further provided in addition to the configuration illustrated in FIG. , and input the output voltage value Vo2 of the power supply device 2 respectively.
- the light source drive circuit 7 included in the N-th light source unit is denoted as a light source drive circuit 7N
- each of the plurality of LED light sources 4 is denoted as an LED light source 4N-m
- each of the plurality of switches 5 is denoted as a switch 5N-m.
- Embodiment 3 in at least one of the plurality of light source units 8-1 and 8-2, dimming control is started from a period in which the number of simultaneous lighting of the plurality of LED light sources is the largest.
- FIG. 11 is an explanatory diagram of a control example of the third embodiment.
- the LEDs are lit in order from the largest lighting duty ratio.
- the LEDs having the smallest lighting duty ratios are turned off in ascending order, and the dimming control is started from the state in which the number of simultaneous lighting of the LED light sources is four in the dimming control period of the LED light sources.
- the light source driving circuits 71 and 72 in each light source unit are controlled so that their respective output currents Io71 and Io72 become the same target current IT7.
- the lighting duty ratio of each LED light source is high as exemplified in FIGS.
- FIG. 11 shows an example in which dimming control is started from a state in which the number of simultaneously lit LED light sources in both light source units is four, only one of the light source units is subject to the above-described control.
- the total current output from the power supply device 2 to each light source unit may be adjusted so as to change from the direction of stepwise decrease.
- the target current values of the light source driving circuit in each light source unit may be set to different target currents IT71 and IT72.
- the light distribution pattern is not restricted, and the light is prevented from being turned off. It becomes possible to realize stable lighting.
- FIG. 12 is an explanatory diagram of a control example according to the fourth embodiment.
- the lighting duty ratios of the four LED light sources are set to 10%, 30%, 60%, and 80%, respectively, and lighting is performed in descending order of each lighting duty ratio, and An example will be described in which the lights are turned off in ascending order of the lighting duty ratio.
- the light source driving circuits 71 and 72 in each light source unit are controlled so that their respective output currents Io71 and Io72 become the same target current IT7.
- the LED light sources 42-1 to 42-4 start dimming control from a state in which the number of simultaneously lit LED light sources is four in the dimming control cycle of the LED light sources.
- the change control of each LED light source is performed from turning off before turning on, and the change in the current Io2-2 output from the power supply device 2 to the light source unit 8-2 is stepwise. Control is performed first in the direction of decreasing, and then the change in Io2-2 increases step by step due to re-lighting control.
- the output voltage value Vo2 of the power supply device 2 is the two-dot chain line voltage waveform in FIG. , it increases to the output voltage value Vo2(max1) higher than the target voltage value VT2 as Io2-2 decreases step by step. It is also assumed that the output voltage value Vo2 of the power supply device 2 decreases to the output voltage value Vo2 (min1) lower than the target voltage value VT2 as Io2-2 increases stepwise thereafter.
- the LEDs 41-1 to 41-4 start dimming control from a state in which the number of simultaneously lit LED light sources is 0 in the dimming control cycle of the LED light sources.
- the change control of each LED light source is performed from lighting before turning off. After that, the change in Io2-1 gradually decreases due to the re-lighting control.
- the output voltage Vo2 of the power supply device 2 is as shown by the broken line voltage waveform in FIG. , and Io2-1, the voltage decreases to the output voltage value Vo2 (min1) lower than the target voltage value VT2. It is also assumed that the output voltage value Vo2 increases to the output voltage value Vo2(max1) higher than the target voltage value VT2 as Io2-2 decreases stepwise thereafter.
- dimming control is started from the period in which the number of simultaneous lighting of the plurality of LED light sources is the largest, and in the light source unit 8-1, the number of simultaneous lighting of the plurality of LED light sources is the largest. Dimming control is started from the period when it decreases.
- each light source unit supplies currents Io72 and Io71, each of which is the target current IT7, to the LED light source included in each light source unit.
- the directions of the stepwise changes in the currents Io2-2 and Io2-1 supplied from the power supply device 2 to the light source units 8-2 and 8-1 are canceled out. , and the fluctuation of the total current of Io2-2 and Io2-1 is suppressed.
- the output voltage value Vo2 of the power supply device 2 changes to the output voltage value Vo2 (max2) lower than the output voltage value Vo2 (max1), and to The minimum voltage value can be suppressed to the output voltage value Vo2 (min2) higher than the output voltage value Vo2 (min1). Therefore, it is possible to more reliably prevent the output voltage value Vo2 from dropping below 4 ⁇ Vf.
- one light source unit is added to the pair of light source units described above to perform the same control as the light source unit 8-1 or 8-2 described above. Therefore, the condition under which the decrease in the output voltage value Vo2 is further suppressed is preferentially selected. As described above, even when there are a plurality of light source units and at least two light sources in each light source unit are controlled with different lighting duty ratios, the light distribution pattern is not restricted, and the light is prevented from being turned off. It becomes possible to realize stable lighting.
- the directions of the stepwise changes in the currents Io2-2 and Io2-1 supplied from the power supply device 2 to the light source unit 8-2 and the light source unit 8-1 are more offset. , and it is possible to prevent the output voltage Vo2 from dropping below 4.times.Vf.
- the combination of the lighting duty ratios of the LED light sources is the same for each of the plurality of light source units, the light distribution pattern for each light source unit can be unified. Therefore, simply by increasing the number of light source units connected to the power supply device 2, it is possible to easily expand the light distribution area with the same characteristics.
- two light source units may be arranged side by side and have light distribution characteristics such that the central portion is the brightest. Cost can be reduced by arranging the plurality of LED elements in the same manner in each light source unit.
- the control shown in FIG. 12 in the fourth embodiment may be changed to the control shown in FIG.
- the light source unit 8-2 including the LED light source 42-m is adjacent to the light source unit 8-1 including the LED light source 41-m, and the LED light source 41-1 and the LED light source illustrated in FIG. 42-4 are arranged adjacent to each other.
- the LED 41-1 side is controlled to have the highest lighting duty ratio and become brighter.
- the LED 42-4 side is controlled to have the highest lighting duty ratio and become brighter.
- the lighting duty ratios of the respective light source units are symmetrical with respect to the central portion of each adjacent light source unit, and the central portion has the highest lighting duty ratio, resulting in a bright light distribution pattern.
- the desired light distribution area may be expanded according to the arrangement, for example, by control as shown in FIG. .
- the light distribution area can be easily adjusted without restricting the light distribution pattern. , it is possible to realize stable lighting that prevents extinguishing.
- Embodiment 6 the configuration illustrated in FIG. 1 or FIG. 10 will be described as an example.
- FIG. 15 shows an example of the gain (loop gain)-frequency characteristic of the open-loop transfer function of the power supply device 2 in FIG. 1 or FIG.
- the configuration of a boost chopper that monitors the output voltage value Vo2 performs negative feedback control, and controls the switching element Q23 will be described as an example.
- the upper limit frequency (zero-cross frequency of loop gain) FBW of the response frequency band shown in FIG. 15 is designed while considering the stability due to the phase margin and gain margin.
- the time required for the power supply device 2 to converge the output voltage value Vo2 to the target value VT2 with respect to the load fluctuation is determined.
- the time from the extinguishing timing of an arbitrary light source of a plurality of light sources to the extinguishing timing of another light source to be extinguished next, and the extinguishing timing of the light source to be extinguished last. to the lighting timing of the light source to be turned on next is set to be shorter than the reciprocal time tBW of the upper limit frequency FBW of the response frequency band of the power supply device 2, so that at least two light sources have different lighting duties. To achieve stable lighting by further preventing extinguishing even when controlling by a ratio.
- FIG. 16 is an explanatory diagram of a control example of the sixth embodiment.
- the lighting duty ratios of the four LED light sources are set to 65%, 75%, 85%, and 95%, and lighting is performed in descending order of each lighting duty ratio, and the lighting duty ratio is small.
- a case is exemplified in which the LED light sources are turned off in order from the first, and then the dimming control is started from a state in which the number of simultaneous lighting of the LED light sources is four in the dimming control cycle of the LED light sources.
- tOFF_x be the time up to the lighting timing of the LED light source. For example, in FIG.
- tOFF_1 is the time until the timing at which the LED light source 4-3 is turned off, and the time from the timing at which the LED light source 4-3 is turned off to the timing at which the LED light source 4-2 is turned off and the timing at which the light source 4-1 is turned off. is tOFF_3, and the time from the timing when the LED light source 4-1 is turned off to the timing when the LED light source 4-2 is turned on is tOFF_4.
- the output current Io2 of the power supply device 2 increases as the equivalent number of LED light sources in series decreases from four to three.
- the output voltage value Vo2 of the power supply device 2 at the end of the period of tOFF_1 does not converge to the target value VT2 within the period of tOFF_1, and becomes a voltage higher than the target value VT2.
- the dimming control cycle by first providing a period in which the output voltage value Vo2 is higher than the target value VT2, it is possible to prevent the output voltage value Vo2 from falling below 4 ⁇ Vf in subsequent dimming control. .
- the output voltage value Vo2 may approach or fall below 4 ⁇ Vf only by setting tOFF_1 ⁇ tBW. In that case, it can be dealt with by adjusting the number and timing of tOFF_x to be shorter than tBW. For example, the output voltage value Vo2 is increased continuously with tOFF_1 ⁇ tBW and tOFF_2 ⁇ tBW, or the output voltage value Vo2 is increased stepwise with tOFF_1 ⁇ tBW and tOFF_3 ⁇ tBW.
- the output voltage value Vo2 after the tOFF_x period becomes a higher voltage as tOFF_x is controlled to be shorter than tBW. Therefore, by adjusting the control time of tOFF_x, the required output voltage value Vo2 may be obtained. As described above, even when at least two light sources in a light source unit are controlled with different lighting duty ratios, it is possible to realize stable lighting that more reliably prevents the light from going out without restricting the light distribution pattern. becomes possible.
- Embodiment 7 the configuration illustrated in FIG. 1 or FIG. 10 will be described as an example.
- the light source device of the present application it is assumed that at least two of the plurality of LED light sources are dimmed with the same lighting duty ratio.
- the case where the lighting duty ratios of the plurality of LED light sources included in the light source unit are different from each other has been exemplified. It is possible that there is
- each lighting timing when dimming at least two LED light sources out of a plurality of LED light sources at the same lighting duty ratio, each lighting timing does not overlap with the lighting duty ratio Between the lighting timing of the LED light source with the largest lighting duty ratio and the lighting timing of the light source with the next smallest lighting duty ratio, or in a state where the lighting timings do not overlap, each lighting timing is set between the lighting timing of the light source with the next largest lighting duty ratio. It is set between the turn-off timing and the turn-off timing of the light source having the next smaller lighting duty ratio.
- the lighting duty ratios of the four LED light sources are set to 10%, 30%, 30%, and 70%, and lighting is performed in order from the largest lighting duty ratio.
- a case is exemplified in which the LED light sources are turned off in ascending order, and then the dimming control is started from a state in which the number of simultaneous lighting of the LED light sources is 0 in the dimming control period of the LED light sources.
- the notation of the LED light source 4N-m in a plurality of light source units is omitted, and hereinafter, the notation of the LED light source 4-m in a single light source unit will be described as a representative. do.
- the LED light sources having the same lighting duty ratio are the LED light sources 4-3 and 4-2. It is also assumed that the lighting duty ratio of the LED light source 4-4 is 10% and the lighting duty ratio of the LED light source 4-1 is 70%.
- the LED light source 4-1 having the largest lighting duty ratio starts lighting first.
- the LED light source 4-3 and the LED light source 4-2 having the next largest lighting duty ratio start lighting.
- the lighting timing of the LED light source 4-3 is controlled to be delayed from the lighting timing of the LED light source 4-2 so that the lighting timing of the LED light source 4-2 does not overlap.
- the LED light source 4-4 with the next largest lighting duty ratio (or the smallest lighting duty ratio) starts lighting.
- the delay of the lighting timing of the LED light source 4-3 described above is determined so that the lighting timing of each LED light source does not overlap within the dimming control period.
- the lighting timing of the LED light source 4-2 may be delayed from that of the LED light source 4-3.
- the delay time is determined so that the turn-off timings of the LED light sources within the dimming control cycle do not overlap each other.
- Embodiment 8 The eighth embodiment will also be described using the configuration illustrated in FIG. 1 or FIG. 10 as an example.
- the controller 3 in FIG. 1 or 10 receives light source control information from, for example, an ECU (Electronic Control Unit) external to the light source device 100, and outputs a switch control signal based on the light source control information.
- an ECU Electronic Control Unit
- a switch control signal based on the light source control information.
- the light source control information As illustrated in Embodiment 1, when an oncoming vehicle is detected by a camera or sensor, a plurality of LED light sources are used so that the oncoming vehicle is not illuminated with light. Among them, there is control information for turning off only a specific LED light source.
- switch control circuit 6N in FIG. 10 controls switch 5-m or switch 5N-m.
- the external ECU When an oncoming vehicle is detected while the vehicle is running, the external ECU outputs a "signal to turn off a specific light source" as light source control information, and the controller 3 receives the signal to turn off the light source.
- controller 3 controls switch 5-m or switch 5N-m through switch control circuit 6 or switch control circuit 6N so that only a specific LED light source is turned off.
- the external ECU when the oncoming vehicle is no longer detected, the external ECU outputs a "signal to restore the lighting (dimming) of the specific light source" as the light source control information, and the controller 3 causes the lighting (dimming) to return. shall be received. In that case, the controller 3 causes the switch 5-m or the switch 5N- It is assumed that m is controlled and the normal state is restored.
- the external ECU while detecting the oncoming vehicle and detecting that the oncoming vehicle is moving, the external ECU will newly turn off the light source so that the oncoming vehicle is not illuminated with light depending on the time. and a "specific light source turn-on (dimming) return instruction signal" for a light source not targeted for turn-off may be output as light source control information.
- the light source including the light source is turned off.
- the lighting duty ratio before turning off the corresponding light source is other than 100%, the light is turned off at the turning off timing of the dimming control and the turned off state is maintained. In this way, even when a specific light source is turned off when an oncoming vehicle or the like is detected, the light distribution pattern is not restricted, and stable lighting is achieved by preventing other light sources from being turned off.
- the corresponding light source when a specific light source that has been turned off based on the light source control information is returned to the turned-on state, if the lighting duty ratio before turning off the corresponding light source is 100%, the corresponding light source is turned off.
- a period in which the number of simultaneous lighting of multiple light sources in a light source unit containing the light source is the lowest or the highest, or a period in which the number of simultaneous lighting transitions from the lowest to the highest, and the number of other light sources in the light source unit Lighting is restored at a timing that does not overlap with the lighting timing, and if the lighting duty ratio before turning off the corresponding light source is other than 100%, lighting is restored at the lighting timing of dimming control, and dimming is performed at a predetermined lighting duty ratio.
- FIG. 19 exemplifies control when the controller 3 receives a "specific light source turn-off instruction signal" from the external ECU.
- FIG. 20 exemplifies the control when the controller 3 receives a "signal for restoring lighting (dimming) of a specific light source" from the external ECU.
- the notation of LED4N-m in a plurality of light source units is omitted, and the notation of LED4-m in a single light source unit will be described as a representative hereinafter.
- the dimming control cycle 1 illustrated in FIG. 19 is the normal dimming control state described above.
- the normal state is the dimming control period 1. is repeated every dimming cycle.
- the two light sources 4-4 are instructed to turn off from the dimming control cycle 2, which is the next dimming control cycle.
- the lighting duty ratios of the LED light source 4-3 and the LED light source 4-4 in normal times are 30% and 100%, respectively.
- the LED light source 4-3 with a normal lighting duty ratio of 30%, as illustrated in (a1) and (c1) of FIG.
- the light is turned off at time t3 OFF in the figure, and the light-off state is maintained from the next dimming control period 3 onward until the lighting (dimming) return signal is received.
- the LED light source 4-3 may be kept off.
- the turn-off timing of the target specific LED light source and other dimming control are performed.
- To easily prevent overlapping with the turn-off timing of a continuing LED light source, and to maintain stable lighting by preventing turn-off of light sources other than specific light sources to be turned off without restricting light distribution patterns. can be realized.
- the LED light source 4-4 with a normal lighting duty ratio of 100%, as illustrated in (a1) of FIG. and at a timing (time t4 OFF in the figure) that does not overlap with the extinguishing timing of other light sources, and the extinguished state is maintained from the next dimming control cycle 3 onward until the lighting (dimming) return signal is received. do.
- the LED light source is turned off at a period when the number of simultaneous lighting of the LED light sources is the smallest in the normal time and at a timing that does not overlap with the turning off timing of the other light sources.
- 19(b1) illustrates the case where the number of simultaneously lit LED light sources at the start of the dimming control cycle is 0, so the LED light sources 4-4 are turned off at the start time t4OFF of the dimming control cycle 2. Turns off and stays off.
- (c1) of FIG. 19 in the dimming control cycle 2, during the period in which the number of simultaneously lit LED light sources transitions from the largest to the smallest in the normal state, and at the same time as the extinguishing timing of the other LED light sources The light may be turned off at a non-overlapping timing (time t4 OFF in the figure).
- the turn-off timing may be the following exceptional timing, for example, the timing of lighting other LED light sources during dimming, or the period during which the number of simultaneous lighting of the LED light sources transitions from the smallest to the largest.
- the dimming control period 4 illustrated in FIG. 20 is based on the above-described "specific light source turn-off instruction signal", and the two LED light sources, LED light source 4-3 and LED light source 4-4, are turned off. is continued.
- the operation shown in FIG. From the dimming control cycle 3 to the dimming control cycle 4 in FIG. 20, the state of the dimming control cycle 3 or 4 shall be repeated for each dimming cycle.
- FIG. 20(a2) illustrates a case where the number of simultaneously lit LED light sources at the start of the dimming control cycle is 0, so at the start of the dimming control cycle 5 (time t4ON in the figure), the LED The light source 4-4 is turned on again and kept on. Further, until the "LED light source 4-4 extinguishing instruction signal" is received again, normal dimming with a lighting duty ratio of 100% is maintained from the next dimming control period 6 onward.
- the dimming control cycle 5 in the dimming control cycle 5, the period during which the number of simultaneous lighting of the LED light sources is the largest in the normal time, and the timing that does not overlap with the lighting timing of the other light sources ( , time t4ON).
- each of the plurality of LED light sources is turned on in order from the one with the largest lighting duty ratio and turned off in order from the one with the smallest lighting duty ratio. can be maintained. Therefore, it is possible to prevent extinguishing and maintain stable lighting without restricting the light distribution pattern.
- the lighting timing may be an exceptional timing such as the following, for example, the timing of extinguishing other LED light sources during dimming, or the period during which the number of simultaneous lighting of the LED light sources transitions from the largest to the smallest. From the above, when controlling at least two LED light sources with different lighting duty ratios, even when turning off a specific light source or turning on (dimming) the specific light source when detecting an oncoming vehicle etc. , it is possible to achieve compatibility with stable lighting by preventing other LED light sources from being turned off without restricting the light distribution pattern.
- the controller, switch control circuit, step-up controller, and step-down controller described in the embodiments are composed of a processor 200 and a storage device 201, as shown in FIG. 21 as an example of hardware.
- the storage device includes a volatile storage device such as a random access memory and a non-volatile auxiliary storage device such as a flash memory.
- an auxiliary storage device such as a hard disk may be provided instead of the flash memory.
- Processor 200 executes a program input from storage device 201 . In this case, the program is input from the auxiliary storage device to the processor 200 via the volatile storage device. Further, the processor 200 may output data such as calculation results to the volatile storage device of the storage device 201, or may store the data in the auxiliary storage device via the volatile storage device.
- the processor 200 may be a microcomputer combined with peripheral circuits.
- controllers may be composed of digital circuits such as FPGA (Field Programmable Gate Array) and CPLD (Complex Programmable Logic Device),
- the step-up controller and step-down controller may be composed of analog circuits including operational amplifiers and comparators, resistors and capacitors, and the like.
- the controller, switch control circuit, step-up controller, and step-down controller may have a configuration in which the above-described processor 200 or peripheral peripheral circuits, FPGA, and analog circuits are mixed, or a DSP (Digital Signal Processor) with a parallel bus configuration. ) may be installed.
- DSP Digital Signal Processor
Landscapes
- Circuit Arrangement For Electric Light Sources In General (AREA)
Abstract
Description
LEDは、光源駆動回路から電流が供給されて点灯する。また複数のLEDを直列に接続して、直列に接続したLED光源の各々に並列にバイパススイッチを設け、このバイパススイッチをオン、オフ制御することによって、LED光源の調光および部分的な消灯を行うようにして、様々な配光パタ-ンを実現する機能が搭載されている。
前記光源駆動回路への入力電源の電圧VINが低下した場合、前記光源駆動回路から必要な順方向電圧m×Vfを印加できず、LED光源の輝度低下またはLED光源の消灯が発生する可能性がある。
本願は、従来の技術が有する上述の課題に対応してなされたものであり、前記複数の直列LED光源のうち、少なくとも二つのLED光源を各々異なる点灯デューティ比で制御する場合でも、配光パタ-ンを制約することなく、電圧低下によるLED光源の消灯を防止した光源装置を提供することを目的としている。
図1は、LED光源を駆動する光源駆動回路を含む光源装置の構成を示す構成図である。以下、LED光源が自動車のヘッドライトに使用される場合について説明する。
図1に示すように、実施の形態1の光源装置100は、入力電圧源1(外部電源)の電圧VIN1を入力として予め定められた値の電圧値を出力する電源装置2と、光源制御情報を基にスイッチ制御信号を出力する制御器3を有し、直列に接続された複数のLED光源4(4-1から4-m、但し、m=1、2、3、4であり、以後同様とする)と、この複数の光源4の各々に並列に接続された複数のスイッチ5(5-1から5-m)と、制御器3が出力したスイッチ制御信号に基づいて複数のスイッチ5(5-1から5-m)のオン、オフを各々制御するスイッチ制御回路6と、電源装置2の出力を入力として、複数のLED光源4に電流を供給する光源駆動回路7とを含んだ光源ユニット8として構成されている。ここで、光源制御情報の例として、光源装置が、車両のヘッドライトに使用されて、カメラまたはセンサ等により対向車を検知した場合に、対向車部分に光が照射されないように、複数のLED光源のうち特定のLED光源だけを消灯するような制御情報が挙げられる。
実施の形態1におけるLED光源4は、図1に示すように複数のLED光源が直列に接続されて構成されている。また、以後の説明では、LED光源の数が4個(m=4)の場合を例に説明を行う。
また、実施の形態1における電源装置2は昇圧チョッパに限定されるものではなく、昇圧機能を有した定電圧出力源であればどのようなものでもよい。例えば、昇降圧チョッパ、フライバックコンバ-タ、H型昇降圧コンバ-タ、SEPIC(Single-Ended Primary-Inductance Converter)等であってもよい。
図4に、スイッチ5(5-1から5-m)の制御信号PWM(5-1から5-m)と、LED光源4(4-1から4-m)の点灯状態、および光源駆動回路7から出力される電圧Vo7と、定電流Io7の関係例を示す。
図4の状態1に示す例のように、スイッチ5(5-1から5-m)がオフ(PWM5-mがLレベル)の場合、光源駆動回路7から出力される定電流Io7はLED光源4(4-1から4-m)に流れる為、LED光源4(4-1から4-m)は点灯状態となる。一方、スイッチ5(5-1から5-m)がオンPWM5-mがHレベル)の場合、光源駆動回路7から出力される定電流Io7はスイッチ5-mに流れる為、LED光源4(4-1から4-m)は消灯状態となる。
ここで、定電流Io7を流した場合にLED光源4(4-1から4-m)に生じる順方向電圧をVfとする。また、定電流Io7を流した場合に、スイッチ5(5-1から5-m)のオン抵抗で生じる電位差は無視できるものとする。
この場合、光源駆動回路7から見た等価的なLED光源の直列個数は1個であるから、光源駆動回路7の出力電圧値は、Vo7=1×Vfとなる。一方、図4に示した状態2では、スイッチ5(5-1から5-m)の各々の制御により、LED光源4-1、LED光源4-2、LED光源4-3、LED光源4-4の経路で定電流Io7が流れる。
この場合、光源駆動回路7から見た等価的なLED光源の直列個数は4個であるから、光源駆動回路7の出力電圧値Vo7は、Vo7=4×Vfとなる。
図5に示すように、比較例においてはLED光源の個数m=3の場合を示している。また比較例においては、各制御信号PWM5-mが同じデューティ比である場合を想定している。図5に示すように、比較例ではLEDが3個あるところ、光源駆動回路7から見た等価的なLED光源の最大直列個数が2個以下(Vo7が2×Vf以下)になるように、各制御信号PWM5-mの位相を各々ずらしている。
しかしながら、スイッチ5(5-1から5-m)によって、少なくとも二つのLED光源を各々異なる点灯デューティ比で制御して配光パタ-ンを生成する場合、全てのLED光源が全点灯になる状態(図5の例ではVo7が3×Vfになる状態)を避けると配光パタ-ンの制約が大きく、所望の安定した点灯が実現できない。また図5の例において、入力電圧源VIN1が2×Vfより低下した場合にはLED光源の光量の低下および消灯を防止できず、安定した点灯が実現できない。
電源装置2の効率を高める方法の一つとして、出力電圧値Vo2をm×Vfより少し高い程度(例えばm×Vfに対し、1V~数V高い電圧など)の出力電圧値Vo2とする方法がある。しかしながら、電源装置2の入力である入力電圧源VIN1が自動車用のバッテリ-である場合、6V~18V程度の幅広い入力電圧変動を考慮する必要がある。
以上のように、電源装置2は入力電圧、および出力電流の双方において幅広い変動を考慮する必要があり、そのような制約の基で安定的な負帰還制御を行う場合、一般に応答周波数帯域の上限周波数(ル-プ・ゲインのゼロクロス周波数)FBWを高くすることは難しい。従って、効率を高める為に電源装置2の出力電圧値Vo2をm×Vfより少し高い程度にすると、速い負荷変動に対し出力電圧値Vo2の定電圧制御が追いつかず、m×Vfを下回る場合が生じ、安定的な点灯を実現することができない。
図6は、実施の形態1の制御例の説明図である。図6では、LED光源4の個数mが4個(m=4)で、各LED光源4を各々異なる点灯デューティ比(各々10%、30%、60%、80%)で制御する場合を例に説明する。
したがって、複数のLED光源の点灯時において、出力電圧値Vo2の電圧値を必要最小限の値にして電源装置2の効率を向上できるとともに、応答周波数帯域の制限による電圧低下を抑制し、消灯を防止した安定的な点灯を実現することができる。
したがって、複数のLED光源の消灯時において、出力電圧値Vo2を必要最小限の電値にするとともに、その変動時の最大電圧を最小限に抑制することで、電源装置2の効率を向上できる。
なお別の効果として、例えば光源駆動回路7の応答制御帯域が十分でなく、スイッチ5-mの制御時にLED光源4-mの等価的な直列数が変動する際に、光源駆動回路7の出力電流Io7を目標電流値IT7に収束させるのに時間がかかる場合でも、変動時のIo7の最大ピ-ク電流値を低減できる為、LED光源の破壊をより防止することも可能になる。
本願の実施の形態2について説明する。なお、以下に例示する各形態において作用または機能が実施の形態1と同様である要素については、実施の形態1の説明で使用した符号を流用して各々の詳細な説明を適宜に省略する。以降の実施の形態における説明についても同様とする。すなわち、各図において同一または相当する部分については、同一符号を付して、重複する説明を省略する。
図7は、実施の形態2の制御例の説明図である。図7は、実施の形態1の図6の例と同様、4個のLED光源の各々の点灯デューティ比を10%、30%、60%、80%とした場合に、各点灯デューティ比が大きいものから順に点灯し、かつ点灯デューティ比が小さいものから順に消灯したうえで、LED光源の調光制御周期において、LED光源の同時点灯数が4個の状態から調光制御を開始する例である。この場合、図7より、前述した図6の例と同様の効果が得られる。
このような制御を行うことで、各LED光源の調光制御に伴う電源装置2の出力電圧値Vo2の変化は上昇する方向から開始される為、出力電圧値Vo2が4×Vfより低下することをより確実に防止することができる。
なお、図7および図8の調光制御の開始時点に至るまでの立ち上げ期間の例を、図9に例示する。図9に示すように、各LED光源の点灯デューティ比が各々10%、30%、60%、80%の場合は最大同時点灯数が4個であるから、立ち上げ期間において、予め全てのLED光源が点灯状態になるよう、段階的に各LED光源に対し点灯制御を行う。
本願の実施の形態3を説明する。実施の形態3では図10に示すように、図1に例示される構成に対し、さらに複数の光源ユニット8-Nを有し、前記複数の光源ユニット8-Nの各々は電源装置2に並列に接続され、電源装置2の出力電圧値Vo2を各々入力する構成とする。ここで、N番目の光源ユニットに含まれる光源駆動回路7は光源駆動回路7N、複数のLED光源4は各々LED光源4N-m、複数のスイッチ5は各々スイッチ5N-mと表記する。
前述したように、図8および図11に例示したように各LED光源の点灯デューティ比が高い場合、各LED光源の点灯タイミングの時間間隔、および消灯タイミングの時間間隔が短くなる為、電源装置2のFBWが低い程、電源装置2の出力電圧値Vo2瞬時的な電圧低下の程度が大きくなる可能性がある。
従って、電源装置2の出力電圧値Vo2は上昇する方向から制御が開始される。電圧の上昇の程度は、電源装置2のFBWの程度に応じて変化する。次に各光源ユニットにおいて、各LED光源の消灯制御が段階的に行われる為、電源装置2から出力される電流の変化は、各々段階的に増える方向に転じ、上昇した出力電圧値Vo2は減少し、目標電圧値に近くなる方向に向かう。
なお、図11では両方の光源ユニットにおいてLED光源の同時点灯数が4個の状態から調光制御を開始する例を示したが、どちらか一方の光源ユニットのみを前述した制御の対象とし、調光制御周期において、電源装置2から各光源ユニットに出力される電流の合計電流が段階的に減る方向から変化するように調整してもよい。また、各光源ユニットにおける光源駆動回路の目標電流値は各々異なる目標電流IT71およびIT72としてもよく、前述した電源装置2からの合計電流が段階的に減る方向から変化するように調整すればよい。
実施の形態4においても、図10に例示される構成で、光源ユニットの数が2個(N=2)、かつ各光源ユニット中には、光源(LED)が各々4個(m=4)含まれる場合を例に説明を行う。前述したように、電源装置2に複数の光源ユニットが接続されることで、電源装置2から出力される電流の変動は複雑に変化する。そこでこの実施の形態4では、実施の形態3に対してさらに、他の光源ユニットの少なくとも一つにおいて、前記複数の光源の同時点灯数が最も少なくなる期間から調光制御を開始する。
この場合は前述したように、各LED光源の変更制御は点灯よりも先に消灯から行われることとなり、電源装置2から光源ユニット8-2に出力される電流Io2-2の変化は段階的に減る方向から先に制御が行われ、その後再点灯の制御により、Io2-2の変化は段階的に増える方向となる。
以上のようにして、光源ユニット8-2では複数のLED光源の同時点灯数が最も多くなる期間から調光制御を開始し、かつ光源ユニット8-1では複数のLED光源の同時点灯数が最も少なくなる期間から調光制御を開始する。
その結果、電源装置2の出力電圧値Vo2は図12中の実線電圧波形のように、変動時の最大電圧値を出力電圧値Vo2(max1)よりも低い出力電圧値Vo2(max2)に、また最小電圧値を出力電圧値Vo2(min1)よりも高い出力電圧値Vo2(min2)に抑制できる。従って、より確実に出力電圧値Vo2が4×Vfより低下することを防止することができる。
以上のことより、光源ユニットが複数ある場合で、各光源ユニット中における少なくとも二つの光源を各々異なる点灯デューティ比で制御する場合でも、配光パタ-ンを制約することなく、より消灯を防止した安定した点灯を実現することが可能となる。
実施の形態5においても、図10に例示される構成で、光源ユニットの数が2個(N=2)、かつ各光源ユニット中には、LED光源4が各々4個(m=4)含まれる場合を例に説明を行う。
前述したように、電源装置2に複数の光源ユニットが接続されることで、電源装置2から出力される電流の変動は複雑に変化する。そこで実施の形態5では、実施の形態3および4に対してさらに、複数の光源ユニットにおいて、任意の光源ユニットにおける複数のLED光源の各点灯デューティ比は各々、他の少なくとも一つの光源ユニットにおける複数の光源の点灯デューティ比のいずれかと同じにする。
ここで、実施の形態3においては図11で、また実施の形態4においては図12で、
2個の光源ユニットの各々において、各LED光源の点灯デューティ比の組み合わせが同じである場合について既に例示している。このようにすることで、まず実施の形態3に対しては、各LED光源の調光制御周期において、電源装置2の出力電圧値Vo2の変化をより確実に上昇する方向から開始でき、出力電圧値Vo2が4×Vfより低下することを防止できる。
また前述した効果に加え、複数の光源ユニットの各々において、各LED光源の点灯デューティ比の組み合わせを同じにしている為に、各光源ユニット毎の配光パタ-ンを統一化できる。従って、電源装置2に接続する光源ユニット数を増すだけで、同じ特性の配光領域を容易に拡張することが可能となる。
図13では、LED光源41-mを含んだ光源ユニット8-1に対し、LED光源42-mを含んだ光源ユニット8-2を隣接させ、図13で例示したLED光源41-1とLED光源42-4が隣り合うように配置するものとする。
また、各光源ユニットで複数のLED素子の配置を異なるように設計したい場合は、その配置に応じて、例えば図14に例示するような制御により、所望の配光領域の拡張を行ってもよい。
実施の形態6においては、図1または図10に例示される構成を例に説明を行う。図15に、図1または図10における電源装置2の一巡伝達関数のゲイン(ル-プ・ゲイン)-周波数特性の例を示す。図2において示したように、この実施の形態6では、電源装置2として、出力電圧値Vo2をモニタして負帰還制御を行い、スイッチング素子Q23を制御する昇圧チョッパの構成を例に説明する。
以上のことより、光源ユニット中における少なくとも二つの光源を各々異なる点灯デューティ比で制御する場合でも、配光パタ-ンを制約することなく、より確実に消灯を防止した安定した点灯を実現することが可能となる。
実施の形態7においては、図1または図10に例示される構成を例に説明を行う。前述したように本願の光源装置では、複数のLED光源のうち、少なくとも二つのLED光源を同じ点灯デューティ比で調光する場合を想定している。これまでの説明は、いずれも光源ユニット中に含まれる複数のLED光源の点灯デューティ比が各々異なる場合について例示してきたが、その他の組み合わせとして、複数のLED光源のうち、点灯デューティ比が同じものがある場合が考えられる。
ここで、実施の形態6と同様、実施の形態7では複数の光源ユニットにおけるLED光源4N-mの表記を省略し、以後は単一の光源ユニットにおけるLED光源4-mの表記を代表として記載する。図17および図18において、点灯デューティ比が同一のLED光源はLED光源4-3とLED光源4-2であるとする。またLED光源4-4の点灯デューティ比が10%、LED光源4-1の点灯デューティ比が70%であるとする。
以上のことより、少なくとも二つの光源を各々異なる点灯デューティ比で制御し、かつ少なくとも二つのLED光源を同じ点灯デューティ比で制御する場合でも、より配光パタ-ンの制約を無くした状態で、消灯を防止した安定した点灯を実現することが可能となる。
実施の形態8においても、図1または図10に例示される構成を例に説明を行う。図1または図10における制御器3は、光源装置100の外部の、例えばECU(Electronic Control Unit)から光源制御情報を入力し、その光源制御情報を基にスイッチ制御信号を出力する。自動車の場合、光源制御情報の例としては、実施の携帯1において例示したように、カメラまたはセンサ等により対向車を検知した場合に、対向車部分に光が照射されないように、複数のLED光源のうち特定のLED光源だけを消灯するような制御情報が挙げられる。
また、走行時に対向車が検知された場合には、外部ECUから光源制御情報として「特定の光源の消灯指示信号」が出力され、制御器3が前記消灯指示信号を受信する。その場合には、特定のLED光源のみ消灯されるよう、制御器3はスイッチ制御回路6またはスイッチ制御回路6Nを介して、スイッチ5-mまたはスイッチ5N-mを制御するものとする。
なお、対向車を検出し、さらに対向車が移動していること検出している間は、その時々に応じて対向車部分に光が照射されないよう、外部ECUから新たに消灯の対象となる光源に対する「特定の光源の消灯指示信号」と、消灯の対象から外れた光源に対する「特定の光源の点灯(調光)復帰指示信号」の両方を合わせ持った光源制御情報として出力されてもよい。
図19および図20は、実施の形態8の制御例の説明図である。図19は、制御器3が外部ECUから「特定の光源の消灯指示信号」を受信した場合の制御について例示したものである。また図20は、制御器3が外部ECUから「特定の光源の点灯(調光)復帰指示信号」を受信した場合の制御について例示したものである。
図19に示す調光制御周期1の途中で、制御器3が前述した「特定の光源の消灯指示信号」を時点t1OFFにおいて受信し、4個あるLED光源のうち、LED光源4-3およびLED光源4-4の2個について、次の調光制御周期である調光制御周期2から消灯を指示する信号内容であったとする。ここで、通常時におけるLED光源4-3およびLED光源4-4の点灯デューティ比は、各々30%と100%であるとする。
または、図19の(b1)に例示するように、調光制御周期2において、通常時にLED光源の同時点灯数が最も少なくなる期間で、かつ他の光源の消灯タイミングと重ならないタイミングで消灯してもよい。図19の(b1)では調光制御周期の開始時のLED光源の同時点灯数が0個である場合を例示しているので、調光制御周期2の開始時点t4OFFでLED光源4-4を消灯し、消灯を維持している。
または図19の(c1)に例示するように、調光制御周期2において、通常時にLED光源の同時点灯数が最も多い状態から少ない状態に遷移する期間で、かつ他のLED光源の消灯タイミングと重ならないタイミング(図中、時点t4OFF)で消灯してもよい。
なお、通常時の点灯デューティ比が100%の特定のLED光源を消灯する場合は、前述した電源装置2の出力電圧値Vo2がm×Vfを下回らないようにすることができる場合、その消灯タイミングは以下のような例外的なタイミング、例えば他のLED光源の調光時の点灯タイミング、LED光源の同時点灯数が最も少ない状態から多い状態に遷移する期間にしてもよい。
通常時の点灯デューティ比が30%のLED光源4-3については、図20の(a2)から(c2)に例示するように、調光制御周期5において、通常時の調光制御の点灯タイミング(図中、時点t3ON)で再点灯し、点灯デューティ比30%で駆動する。また、再度「LED光源4-3の消灯指示信号」を受信するまでは、次の調光制御周期6以降は点灯デューティ比が30%の通常時の調光を維持する。
通常時の点灯デューティ比が100%のLED光源4-4については、図20の(a2)に例示するように、調光制御周期5において、通常時にLED光源の同時点灯数が最も少なくなる期間で、かつ他のLED光源の点灯タイミングと重ならないタイミング(図中、時点t4ON)で再点灯する。
または、図20の(b2)に例示するように、調光制御周期5において、通常時にLED光源の同時点灯数が最も多くなる期間で、かつ他の光源の点灯タイミングと重ならないタイミング(図中、時点t4ON)で再点灯してもよい。
このようにすることで、通常時の点灯デューティ比が100%の特定のLED光源を点灯復帰する信号を受信した場合に、対象となる特定のLED光源の再点灯タイミングと、他の調光制御が続行されているLED光源の点灯タイミングとが重なることを容易に防止し、複数のLED光源の各々を点灯デューティ比が大きいものから順に点灯し、かつ点灯デューティ比が小さいものから順に消灯する状態を維持できる。従って、配光パタ-ンを制約することなく、消灯を防止した安定した点灯の維持を実現できる。
以上のことより、少なくとも二つのLED光源を各々異なる点灯デューティ比で制御する場合で、対向車等検出時等での特定光源の消灯あるいはその特定光源の点灯(調光)復帰を行う場合にも、配光パタ-ンを制約することなく、その他のLED光源の消灯を防止した安定的な点灯との両立を実現することが可能となる。
また、以上の実施の形態では、光源としてLED光源をと仕上げて説明したが、電力によって制御される発光源であれば同様に対応することができる。
従って、例示されていない無数の変形例が、本願明細書に開示される技術の範囲内において想定される。例えば、少なくとも1つの構成要素を変形する場合、追加する場合または省略する場合、さらには、少なくとも1つの構成要素を抽出し、他の実施の形態の構成要素と組み合わせる場合が含まれるものとする。
Claims (10)
- 外部電源の出力を受けて予め定めた値の電圧を出力する電源装置と、光源ユニットとを備え、
前記光源ユニットは、直列接続された複数の光源と、前記光源の各々に並列に接続されたスイッチと、前記電源装置からの出力電力を受けて前記光源と前記スイッチとの構成に電流を供給する光源駆動回路と、前記スイッチをオンオフ制御するスイッチ制御回路とを備え、前記スイッチをオンオフすることによって複数の前記光源を点灯デューティ比に応じて調光制御し、少なくとも二つの前記光源の点灯デューティ比は互いに異なり、前記光源の各々を前記点灯デューティ比が大きい光源から順に点灯し、かつ前記点灯デューティ比の小さい光源から順に消灯するようにしたことを特徴とする光源装置。 - 光源制御情報を基にスイッチ制御信号を出力する制御器をさらに備え、前記スイッチ制御回路は、前記制御器のスイッチ制御信号を基に複数の前記スイッチのオンオフを各々制御することを特徴とする請求項1に記載の光源装置。
- 前記光源ユニットを複数備えていることを特徴とする請求項2に記載の光源装置。
- 少なくとも一つの前記光源ユニットにおいて、複数の前記光源の同時点灯数が最も多くなる期間から調光制御を開始することを特徴とする請求項1から3のいずれか1項に記載の光源装置。
- 複数の前記光源ユニットのうちの少なくとも一つにおいて、複数の前記光源の同時点灯数が最も多くなる期間から調光制御を開始し、複数の前記光源ユニットのうちの他の少なくとも一つにおいて、複数の前記光源の同時点灯数が最も少なくなる期間から調光制御を開始することを特徴とする請求項3に記載の光源装置。
- 複数の前記光源ユニットのうちの少なくとも一つにおける複数の前記光源の各点灯デューティ比が、複数の前記光源ユニットのうちの他の少なくとも一つにおける複数の前記光源の各点灯デューティ比と同じであることを特徴とする請求項3または5に記載の光源装置。
- 少なくとも1つの前記光源ユニットにおいて、複数の前記光源のうちの任意の光源の消灯タイミングから、次に消灯される他の光源の消灯タイミングまでの時間、および最後に消灯される光源の消灯タイミングから、次に点灯される光源の点灯タイミングまでの時間の少なくとも一方が、前記電源装置の応答周波数帯域の上限周波数の逆数時間より短いことを特徴とする請求項1から6のいずれか1項に記載の光源装置。
- 少なくとも1つの前記光源ユニットにおける前記複数の光源のうち、少なくとも二つの光源を同じ点灯デューティ比で調光する場合、各点灯タイミングが重ならない状態で、各点灯タイミングを次に点灯デューティ比が大きい光源の点灯タイミングと、次に点灯デューティ比が小さい光源の点灯タイミングとの間にする、または各消灯タイミングが重ならない状態で、各消灯タイミングを次に点灯デューティ比が大きい光源の消灯タイミングと、次に点灯デューティ比が小さい光源の消灯タイミングとの間にすることを特徴とする請求項1から7のいずれか1項に記載の光源装置。
- 少なくとも1つの前記光源ユニットにおいて、複数の前記光源のうち特定の光源を消灯する場合、該当する光源の消灯前の点灯デューティ比が100%の場合は、当該光源が含まれる前記光源ユニットの中の複数の光源の同時点灯数が最も少ない期間または最も多い期間、または同時点灯数が最も多い状態から少ない状態に遷移する期間でかつ当該光源ユニットの中の他の光源の消灯タイミングと重ならないタイミングで消灯し、該当する光源の消灯前の点灯デューティが100%以外の場合は、調光制御の消灯タイミングで消灯し、消灯状態を維持することを特徴とする請求項1から8のいずれか1項に記載の光源装置。
- 特定の前記光源の消灯状態を点灯状態に復帰する場合、該当する光源の消灯前の点灯デューティ比が100%の場合は、当該光源が含まれる前記光源ユニットの中の複数の光源の同時点灯数が最も少ない期間または最も多い期間、または同時点灯数が最も少ない状態から多い状態に遷移する期間でかつ当該光源ユニットの中の他の光源の点灯タイミングと重ならないタイミングで点灯を復帰し、該当する光源の消灯前の点灯デューティ比が100%以外の場合は、調光制御の点灯タイミングで点灯復帰し、予め定めた点灯デューティ比で調光を維持することを特徴とする請求項9に記載の光源装置。
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Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
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JP2009134933A (ja) * | 2007-11-29 | 2009-06-18 | Mitsubishi Electric Corp | Led点灯装置および車両用前照灯 |
WO2018047915A1 (ja) * | 2016-09-09 | 2018-03-15 | 株式会社小糸製作所 | 点灯回路、車両用灯具および光源の駆動方法 |
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2021
- 2021-01-22 WO PCT/JP2021/002208 patent/WO2022157917A1/ja active Application Filing
- 2021-01-22 US US18/269,986 patent/US20240074017A1/en active Pending
- 2021-01-22 JP JP2021539439A patent/JP7019874B1/ja active Active
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
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JP2009134933A (ja) * | 2007-11-29 | 2009-06-18 | Mitsubishi Electric Corp | Led点灯装置および車両用前照灯 |
WO2018047915A1 (ja) * | 2016-09-09 | 2018-03-15 | 株式会社小糸製作所 | 点灯回路、車両用灯具および光源の駆動方法 |
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JPWO2022157917A1 (ja) | 2022-07-28 |
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