JP2017021968A - Lighting device, luminaire for vehicle and vehicle using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting device capable of reducing temporal variation of the brightness of output light, a luminaire for a vehicle and a vehicle using the same.SOLUTION: A DC-DC converter 11 supplies current to a plurality of LED light sources 3a-3d for irradiating a common area with light. A control circuit 13 controls a plurality of switching circuits 12a-12d to perform PWM-control on a period during which current flows through each of the plurality of LED light sources 3a-3d. In a second period including the first period in which one of the plurality of LED light sources 3a-3d is turned off, the control circuit 13 selects at least one LED light source other than the above one LED light source out of the plurality of LED light sources 3a-3d. Further, the control circuit 13 controls the output of the DC-DC converter circuit 11 so that the brightness of light emitted from the plurality of LED light sources 3a-3d is constant over the entire period.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a lighting device, a vehicle lighting device, and a vehicle using the same, and more particularly to a lighting device capable of dimming an LED light source, a vehicle lighting device, and a vehicle using the same.

  2. Description of the Related Art Conventionally, there has been proposed an LED lighting device that includes a plurality of LED arrays in which a plurality of LEDs (Light Emitting Diodes) are connected in series, and in which a plurality of LED arrays are connected in parallel (see, for example, Patent Document 1).

  In this LED lighting device, when the LED row is turned on, at least one of the LED rows is sequentially turned off every predetermined time, and a stress is applied to the LEDs by providing a period during which no current flows through the LEDs. .

JP 2010-135136 A

  By the way, as a method of dimming the LED, there are a PWM dimming method that adjusts a period in which a current flows through the LED and a DC dimming method that adjusts a current value of a current flowing through the LED. In the DC dimming method, when the current flowing through the LED is reduced, the color of light emitted from the LED may change. On the other hand, in the PWM dimming method, the color of light emitted from the LED hardly changes, but the brightness of the light emitted from the LED changes with time when the LED is periodically turned off. There was a desire to reduce the change over time.

  This invention is made | formed in view of the said subject, and it aims at providing the lighting device which can reduce the temporal change of the brightness of irradiated light, the illuminating device for vehicles, and a vehicle using the same.

  The lighting device of the present invention switches between a power supply circuit that supplies current to a plurality of LED light sources that emit light to a common area, and a state in which current flows and a state in which current does not flow for each of the plurality of LED light sources A plurality of switching circuits; and a control circuit that performs PWM control of a period in which a current flows through each of the plurality of LED light sources by controlling the plurality of switching circuits, and the control circuit includes the plurality of LED light sources. Among the plurality of LED light sources, at least one LED light source other than the one LED light source is turned on and irradiated from the plurality of LED light sources in a second period including a first period in which one LED light source is turned off. The output of the power supply circuit is controlled so that the brightness of the emitted light is constant over the entire period.

  The vehicle lighting device according to the present invention includes the above-described lighting device, a pair of main bodies that hold the lighting device and are respectively attached to a left side and a right side of a vehicle body, and the plurality of LEDs that are separately held by the pair of main bodies. And the control circuit held in each of the pair of main bodies performs PWM control of the plurality of LED light sources in synchronization with each other.

  A vehicle according to the present invention includes the above lighting device, the plurality of LED light sources, and a vehicle body that holds the lighting device and the plurality of LED light sources.

  According to the lighting device of the present invention, the temporal change in the brightness of the output light can be reduced.

  According to the vehicle lighting device of the present invention, temporal changes in the brightness of output light can be reduced.

  According to the vehicle of the present invention, the temporal change in the brightness of the output light can be reduced.

It is a block diagram of the lighting device of an embodiment. It is a figure explaining the light distribution of the LED light source lighted by the lighting device of an embodiment. It is a wave form diagram at the time of making a light control level 75% in the lighting device of embodiment. FIG. 4A is a waveform diagram of an output voltage of the lighting device of the embodiment, and FIG. 4B is a waveform diagram of an output voltage of a comparative example. It is a wave form diagram in case the light control level is 43.75% in the lighting device of embodiment. It is a wave form diagram in case the light control level is 18.75% in the lighting device of embodiment. It is a figure explaining the relationship between the output voltage of the lighting device of embodiment, the output voltage of a comparative example, and the exposure time of a camera. It is the figure which showed the output and total luminous flux of the LED light source in the lighting device of embodiment. It is the figure which showed another example of the output of a LED light source, and a total luminous flux in the lighting device of embodiment. It is the figure which showed another example of the output of an LED light source, and a total luminous flux in the lighting device of embodiment. It is the figure which showed another example of the output of an LED light source, and a total luminous flux in the lighting device of embodiment. It is the figure which showed another example of the output of an LED light source, and a total luminous flux in the lighting device of embodiment. It is a perspective view which shows the front part of the vehicle of embodiment. It is the top view which looked at the vehicles of an embodiment from the upper part. It is a block diagram which shows the other circuit structure of the lighting device of embodiment.

  Below, the lighting device of this embodiment is demonstrated, referring drawings. The lighting device 1 according to the present embodiment is used to light a light source (for example, a headlamp) mounted on a vehicle (for example, an automobile or a motorcycle). In recent years, there is a case where the headlamp is dimmed and used as a daytime running lamp, and the lighting device 1 of the present embodiment turns on the light source when used as a headlamp, for example, and daytime running lamp. The light source is dimmed when used as a lamp. However, the configuration described below is only an example of the present invention. The present invention is not limited to the following embodiments, and various modifications can be made according to the design and the like as long as they do not depart from the technical idea of the present invention.

  As illustrated in FIG. 1, the lighting device 1 of the present embodiment includes a DC-DC converter (power supply circuit) 11, a plurality (four in the present embodiment) of switching circuits 12 a to 12 d, and a control circuit 13. A plurality of (four in the present embodiment) LED light sources 3a to 3d are turned on. Moreover, the vehicle lighting device 20 of the present embodiment includes the lighting device 1 and the LED light sources 3a to 3d.

  Each of the LED light sources 3a to 3d includes one or a plurality of light emitting diodes. The LED light sources 3a to 3d irradiate light to a common area. FIG. 2 is a diagram for explaining the light distribution of the LED light sources 3a to 3d. The LED light sources 3a to 3d are mounted on the substrate 31. The light emitted from the LED light sources 3 a to 3 d is incident on one optical lens 4, and the light distribution is controlled by the optical lens 4 so as to irradiate the common area A 1. Therefore, regardless of which of the four LED light sources 3a to 3d is lit, the light emitted from the LED light source is irradiated onto the area A1 by the optical lens 4. The light distribution in the area A1 is shown on the upper side of FIG. 2, and the light distribution is such that the brightness is brighter toward the center of the area A1. In addition, although the lighting device 1 of this embodiment lights up the four LED light sources 3a to 3d, the number of LED light sources is not limited to four, and if the number of LED light sources is plural, an appropriate number is used. Good.

  The DC-DC converter 11 is a power supply circuit whose output voltage and output current are variable. The DC-DC converter 11 converts the voltage value of the power supply voltage input from the DC power supply 2 into a predetermined voltage value and outputs it. The DC-DC converter 11 controls the current value of the output current (current flowing through the LED light sources 3a to 3d) according to the control signal input from the control circuit 13. The DC-DC converter 11 converts the power supply voltage into a voltage value (predetermined voltage value) corresponding to a current value flowing through the LED light sources 3a to 3d in accordance with a control signal input from the control circuit 13. Thereby, the current value may be adjusted. LED light sources 3a to 3d are connected between the output terminals of the DC-DC converter 11, and the output of the DC-DC converter 11 is supplied to the LED light sources 3a to 3d.

  The switching circuits 12a to 12d are connected in parallel with the LED light sources 3a to 3d, respectively. The switching circuits 12a to 12d are switching elements that are turned on or off according to a control signal input from the control circuit 13, for example. Examples of this type of switching element include a MOSFET (Metal Oxide Semiconductor Field-Effect Transistor) and an IGBT (Insulated Gate Bipolar Transistor).

  The control circuit 13 determines a duty ratio for PWM control of the LED light sources 3a to 3d based on a dimming signal input from an external circuit (such as an ECU (Engine Control Unit) mounted on the vehicle), for example. Then, the control circuit 13 controls the switching circuits 12a to 12d to perform PWM control of the ON period in which current flows in each of the LED light sources 3a to 3d. For example, when the control circuit 13 turns off the switching circuit 12a, a voltage is applied to the LED light source 3a, a current flows through the LED light source 3a, and the LED light source 3a is turned on. When the control circuit 13 turns on the switching circuit 12a, a current flows through the switching circuit 12a and no current flows through the LED light source 3a, so the LED light source 3a is turned off. Here, the control circuit 13 turns on at least one LED light source other than one LED light source that is turned off in the second period including the first period in which one LED light source is turned off among the LED light sources 3a to 3d. . Then, the control circuit 13 outputs the output (output voltage or output current, or output voltage and output) of the DC-DC converter 11 so that the brightness of the light emitted from the plurality of LED light sources 3a to 3d is constant over the entire period. Control both current).

  Here, when the control circuit 13 performs PWM control on each of the plurality of LED light sources (four LED light sources 3a to 3d in the present embodiment), a period in which each of the plurality of LED light sources is turned off is referred to as a “first period”. In addition, a period including a first period in which each of the plurality of LED light sources is turned off, and a period in which at least one LED light source other than the turned off LED light source is turned on is referred to as a “second period”.

  The control circuit 13 is realized by using, for example, a microcomputer, and various functions are realized by the microcomputer executing programs. Here, the program executed by the microcomputer may be stored in advance in a memory, or may be provided via a telecommunication line or recorded in a recording medium.

  In the lighting device 1 of the present embodiment, four LED light sources 3a to 3d are connected in series between output terminals of the DC-DC converter 11, and switching circuits 12a to 12d are connected in parallel to the LED light sources 3a to 3d, respectively. ing. When any of the LED light sources 3a to 3d has an open failure, current does not flow to the LED light source that has failed to open. Therefore, the control circuit 13 monitors the current flowing through each of the LED light sources 3a to 3d, for example. Can detect an open failure of the light source. When the control circuit 13 detects an open failure of the LED light sources 3a to 3d, it turns on the remaining LED light sources by turning on the switching circuits 12a to 12d connected in parallel to the LED light sources 3a to 3d having the open failure. be able to. Moreover, the control circuit 13 can implement | achieve the light control level according to the light control signal by adjusting the on-duty ratio of LED light sources other than the LED light source which carried out an open failure among LED light sources 3a-3d.

  Next, operation | movement of the lighting device 1 of this embodiment is demonstrated.

  FIG. 3 shows the voltages V3a, V3b, V3c, V3d applied to the LED light sources 3a, 3b, 3c, 3d, respectively, when the LED light sources 3a, 3b, 3c, 3d are lit at a dimming level of 75%. It shows the luminous flux of light emitted from the LED light sources 3a to 3d.

  The control circuit 13 individually controls the periods in which the current flows to the LED light sources 3a to 3d based on the dimming signal input from the external circuit, and the on-duty is set to 75% in the example of FIG. Assuming that the time of one cycle of PWM control is T1, the control circuit 13 shifts the timing at which the LED light sources 3a to 3d start to turn on by (T1 / 4), and turns them on in the order of the LED light sources 3a, 3d, 3c, 3b. ing.

  Here, FIG. 4A shows the sum of the voltages V3a to V3d applied to the LED light sources 3a to 3d, that is, the output voltage V11 of the DC-DC converter 11. On the other hand, FIG. 4B shows the output voltage V11 of the DC-DC converter when the dimming level is 75% in the comparative example in which the PWM control is performed so that the four LED light sources 3a to 3d are simultaneously turned on / off. Yes.

  When PWM control as shown in FIG. 3 is performed, the overshoot amount dV1 is a voltage generated for one of the LED light sources 3a to 3d, so the overshoot amount dV2 when the LED light sources 3a to 3d are turned on simultaneously. (See FIGS. 4A and 4B). Therefore, an electrical component having a lower withstand voltage can be used as the circuit component constituting the lighting device 1, and the cost can be reduced and the size can be reduced.

  Further, when PWM control as shown in FIG. 3 is performed, there is no period in which all the LED light sources 3a to 3d are extinguished, and the brightness of light emitted from the LED light sources 3a to 3d is substantially constant over the entire period. And the occurrence of flicker can be suppressed. Thus, since the temporal change in the brightness of the irradiation light of the LED light sources 3a to 3d is reduced, even when the region irradiated with the light from the LED light sources 3a to 3d is shot with the camera, the shooting is performed with the camera. It is possible to reduce the possibility that bright and dark stripes will appear in the image.

  Further, the control circuit 13 performs PWM control for each of the LED light sources 3a to 3d so that the number of LED light sources 3a to 3d that are turned on simultaneously is constant (three in the example of FIG. 3). Thereby, the brightness of the light irradiated from the LED light sources 3a to 3d can be made substantially constant over the entire period.

  FIG. 3 shows the voltages V3a to V3d and V11 when the dimming level is 75%, but the dimming levels of the LED light sources 3a to 3d can be appropriately changed. FIG. 5 shows voltages V3a to V3d and V11 when the dimming level is 43.75%, and FIG. 6 shows voltages V3a to V3d and V11 when the dimming level is 18.75%.

  When the control circuit 13 performs PWM control so that the timings at which the four LED light sources 3a to 3d start to light are shifted by time (T1 / 4), if the dimming level is less than 25%, the LED light sources 3a to 3d are all There will be a period to turn off.

  Here, when the frame period of the camera that captures the area irradiated with the light from the LED light sources 3a to 3d is (1/30) second, and 10% of the frame period is the exposure time per line, per line The exposure time is about 3.33 msec. FIG. 7 shows the voltage V11 when the timing at which the four LED light sources 3a to 3d start to turn on is shifted by (T1 / 4) when the dimming level is 18.75%. Moreover, when the dimming level is 18.75%, the voltage V11 when the four LED light sources 3a to 3d are simultaneously turned on / off (comparative example) is shown in the upper part of FIG. T21 and T22 in FIG. 7 indicate the exposure time of the camera. In the example of FIG. 7, the exposure times T21 and T22 are longer than (13/4) × T1 and shorter than (14/4) × T1. It has become. Therefore, when the four LED light sources 3a to 3d are turned on / off simultaneously, the LED light source is turned on four times at the exposure time T21, but the LED light source is turned on only three times at the exposure time T22, and the exposure amount is 3/4. Therefore, the camera image flickers. On the other hand, when the timings at which the four LED light sources 3a to 3d start to light are shifted by (T1 / 4), the LED light source lights 13 times during the exposure time at any of the exposure times T21 and T22. The variation in exposure amount is reduced. Therefore, the flicker which generate | occur | produces in the image of a camera can be suppressed.

  Next, the operation of the characteristic part of the lighting device 1 of the present embodiment will be described with reference to FIGS. In the description of FIGS. 8 to 12, the number of LED light sources is assumed to be two (LED light sources 3a and 3b). 8 to 12, the upper stage and the middle stage show the outputs (light outputs) L3a and L3b of the LED light sources 3a and 3b, respectively, and the lower stage shows the total luminous flux of the LED light sources 3a and 3b. Note that the number of LED light sources is not limited to two, and may be three or more.

  The control circuit 13 sets the on-duty ratio of the LED light sources 3a and 3b to 50% when a dimming signal having a dimming level of 50% is input from an external circuit. Furthermore, the control circuit 13 performs the other LED light source (LED in FIG. 8) in the second period T12 including the first period T11 in which one of the LED light sources 3a and 3b (LED light source 3b in FIG. 8) is turned off. The light source 3a) is turned on. As a result, the on-duty ratio of the LED light source 3b exceeds 50%, but both the LED light sources 3a and 3b are lit during the periods T13 and T14 of the second period T12 excluding the first period T11. Therefore, even when the timing at which the LED light source 3a is turned on due to the influence of the circuit operation delay or the like is delayed, the situation where both the LED light sources 3a and 3b are extinguished can be avoided if the timing deviation is within the period T13. . Similarly, even when the operation speed of the circuit changes and the timing at which the LED light source 3a is turned off is advanced, the situation where both the LED light sources 3a and 3b are turned off is avoided if the timing difference is within the period T14. it can. The control circuit 13 controls the DC-DC converter 11 so that the outputs L3a and L3b of the LED light sources 3a and 3b are constant, and a constant current flows through the LED light sources 3a and 3b. Therefore, in the periods T13 and T14, The total luminous flux obtained by adding the luminous fluxes of the LED light sources 3a and 3b exceeds the dimming level of 50%.

  Therefore, in the lighting device 1 of the present embodiment, the control circuit 13 outputs the output of the DC-DC converter 11 so that the brightness (light flux) of the light emitted from the LED light sources 3a and 3b is constant over the entire period. Control (see FIG. 9). That is, the control circuit 13 causes each light output during the periods T13 and T14 when both the LED light sources 3a and 3b are lit to be half of the light output during the period when only one of the LED light sources 3a and 3b is lit. The output of the DC-DC converter 11 is controlled. As a result, the total luminous flux obtained by adding the luminous fluxes of the LED light sources 3a and 3b becomes constant over the entire period, and the change in brightness can be suppressed. Moreover, even if the timing at which the LED light source 3a is turned on is delayed or the timing at which the LED light source 3a is turned off is advanced, if the timing deviation is within the period T13 or T14, both the LED light sources 3a and 3b are present. Both can be prevented from turning off.

  In addition, although the control circuit 13 makes the outputs L3a and L3b of the LED light sources 3a and 3b substantially the same in the periods T13 and T14, they may be controlled to different outputs. That is, the control circuit 13 controls the brightness of the LED light sources 3a and 3b to substantially the same brightness in the periods T13 and T14, but may control the brightness of the LED light sources 3a and 3b to different brightness. .

  In this case, it is assumed that the DC-DC converter 11 includes a converter circuit that supplies a direct current output (direct current power) to the LED light source 3a and a converter circuit that supplies a direct current output to the LED light source 3b. The control circuit 13 can individually control the output supplied from the DC-DC converter 11 to the LED light source 3a and the output supplied from the DC-DC converter 11 to the LED light source 3b.

  For example, as shown in FIG. 10, in the period T13, the control circuit 13 outputs the output L3a when the output L3a of the LED light source 3a is lower than the output L3b of the LED light source 3b and the total of the outputs L3a and L3b is on. Alternatively, the output of the DC-DC converter 11 is controlled so as to be the same as L3b. Further, in the period T14, the control circuit 13 has the output L3a of the LED light source 3a higher than the output L3b of the LED light source 3b, and the sum of the outputs L3a and L3b is the same as the output L3a or L3b when one lamp is turned on. The output of the DC-DC converter 11 is controlled. As a result, the total luminous flux obtained by adding the luminous fluxes of the LED light sources 3a and 3b becomes constant over the entire period, and the change in brightness can be suppressed.

  Further, in the control example of FIG. 10, the control circuit 13 controls the outputs L3a and L3b of the LED light sources 3a and 3b to constant outputs during the periods T13 and T14, but as shown in FIG. The outputs L3a and L3b of 3b may be continuously changed.

  That is, in the period T13, the control circuit 13 continuously increases the output L3a of the LED light source 3a from zero to the output when one lamp is lit, and continuously outputs the output L3a from the output when one lamp is lit to zero at time T14. The output of the DC-DC converter 11 is controlled so as to decrease. Further, the control circuit 13 continuously decreases the output L3b of the LED light source 3b from the output at the time of lighting one lamp to zero in the period T13, and continuously from the output L3b to the output at the time of lighting one lamp in the period T14. The output of the DC-DC converter 11 is controlled so as to increase. Then, the control circuit 13 controls the output of the DC-DC converter 11 so that the sum of the outputs L3a and L3b of the LED light sources 3a and 3b is the same as the output when one lamp is lit during the periods T13 and T14. As a result, the total luminous flux obtained by adding the luminous fluxes of the LED light sources 3a and 3b becomes constant over the entire period, and the change in brightness can be suppressed.

  In addition, when the converter circuit which supplies direct-current output to LED light source 3a, 3b has a smoothing capacitor, the output L3a, L3b of LED light source 3a, 3b is shown by the charging characteristic and discharge characteristic of the smoothing capacitor of each converter circuit. You may change with time.

  As shown in FIG. 12, when the converter circuit that supplies the DC output to the LED light source 3a starts operating at the beginning of the second period T12, the smoothing capacitor is charged in the period T13, and the output L3a of the LED light source 3a gradually increases. To do. In the second period T14, when the converter circuit that supplies the DC output to the LED light source 3a stops, the smoothing capacitor of the converter circuit is discharged, and the output L3a of the LED light source 3a gradually decreases. Further, when the converter circuit that supplies the DC output to the LED light source 3b stops at the beginning of the second period T12, the smoothing capacitor is discharged in the period T13, and the output L3b of the LED light source 3b gradually decreases. In the period T14, when the converter circuit that supplies the DC output to the LED light source 3b starts operating, the smoothing capacitor of the converter circuit is charged, and the output L3b of the LED light source 3b gradually increases.

  Even in this case, in the periods T13 and T14, the sum of the outputs L3a and L3b of the LED light sources 3a and 3b is substantially the same as the output when one lamp is lit, and the total luminous flux obtained by adding the luminous fluxes of the LED light sources 3a and 3b is Since it is constant over the entire period, changes in brightness can be suppressed.

  Further, in the control method of FIGS. 8 to 12, there is no period in which both the LED light sources 3a and 3b are extinguished, and either one of the LED light sources 3a and 3b is always lit. If it uses for this headlamp apparatus, the lamp | ramp which always lights LED light source 3a, 3b is realizable.

  Next, the vehicle lighting device 20 using the lighting device 1 of the present embodiment will be described with reference to FIGS. 1 and 13. In the description of FIG. 13, the description will be made with reference to the vertical, horizontal, and front-back directions indicated by arrows in FIG.

  The vehicle lighting device 20 is a lighting device that lights a headlamp of the vehicle 50, for example.

  The main body 21 of the vehicle lighting device 20 is attached to the left or right side of the front portion of the vehicle body 51. The main body 21 accommodates a traveling headlamp (high beam) 30A and a passing headlamp (low beam) 30B, and the main body 21 holds the lighting device 1. Here, the LED light sources 3a to 3d described above serve as the light source of the traveling headlamp 30A or 30B. FIG. 13 is a schematic diagram, and the lighting device 1 and the main body 21 are separated from each other, but the lighting device 1 is actually held by the main body 21.

  The lighting device 1 of the left and right vehicle lighting devices 20 lights the headlamps 30A and 30B according to the operation of a switch provided in the driver's seat in the vehicle, the brightness of external light detected by the brightness sensor, or the like. Or turn it off. The control circuit 13 of the lighting device 1 performs dimming control on the LED light sources 3a to 3d serving as the light sources of the headlamps 30A and 30B at a duty ratio corresponding to the dimming level set by the dimming signal. Then, the control circuit 13 turns on at least one LED light source other than the one LED light source that is turned off in the second period including the first period in which one LED light source is turned off among the LED light sources 3a to 3d. In addition, the control circuit 13 controls the output of the DC-DC converter 11 so that the brightness of light emitted from the plurality of LED light sources 3a to 3d is constant over the entire period.

  Thereby, there is no period during which all the LED light sources 3a to 3d are turned off. The output of the DC-DC converter 11 (output voltage or output current, or both output voltage and output current) is set so that the brightness of light emitted from the plurality of LED light sources 3a to 3d is constant over the entire period. Since it is controlled, the temporal change in the brightness of the irradiation light can be reduced.

  Moreover, in this embodiment, the lighting device 1 of the left and right vehicle lighting devices 20 communicates via the communication bus 5 and has a timing for turning on or off the LED light sources 3a to 3d constituting the headlamps 30A and 30B. You may synchronize. Moreover, the control circuit 13 with which the left and right vehicle lighting devices 20 respectively have, for example, the LED light sources 3a to 3d of the right vehicle lighting device 20 at the timing of turning off the LED light sources 3a to 3d of the left vehicle lighting device 20. May be lit. Thus, by turning on the other LED light sources while one of the LED light sources 3a to 3d illuminating the same region is turned off, it is possible to avoid a situation in which the plurality of LED light sources 3a to 3d are turned off at the same time. Improves.

  By the way, although the vehicle lighting device 20 of the present embodiment is a lighting device that lights the headlamp of the vehicle 50, a lamp other than the headlamp may be turned on. For example, the above-described lighting device 1 may be used to turn on the back lamp 22, a decorative lamp 23 (so-called signature light), or a fog lamp. When the lighting device 1 performs dimming control as described above when the plurality of LED light sources constituting the back lamp 22 and the lamp 23 are dimmed by the PWM dimming method, the plurality of LED light sources are turned off simultaneously. Can be avoided. In addition, since the total luminous flux of the plurality of LED light sources can be made substantially constant, the occurrence of flicker can be suppressed. Therefore, when shooting the surroundings of the vehicle 50 with a camera, such as a drive recorder, or when displaying an image of the surroundings (for example, the rear) of the vehicle 50 with a camera or using it for driving control, Light and dark stripes are less likely to occur in the image.

  By the way, in the lighting device 1 of the present embodiment, the LED light sources 3a to 3d are connected in series between the output ends of the DC-DC converter 11, but as shown in FIG. The LED light sources 3a to 3d may be connected in parallel. In the circuit example of FIG. 15, switching circuits 12a to 12d are connected in series with each of the LED light sources 3a to 3d. Although the switching circuits 12a to 12d are connected to the low potential side of the LED light sources 3a to 3d, respectively, the switching circuits 12a to 12d may be connected to the high potential side of the LED light sources 3a to 3d, respectively.

  The control circuit 13 controls the switching circuits 12a to 12d to perform PWM control of the ON period in which current flows in each of the LED light sources 3a to 3d. The control circuit 13 turns on at least one LED light source other than one LED light source that is turned off in a second period including the first period in which one LED light source is turned off among the LED light sources 3a to 3d. Then, the control circuit 13 controls the output of the DC-DC converter 11 so that the brightness of light emitted from the plurality of LED light sources 3a to 3d is constant over the entire period. Here, the DC-DC converter 11 should just be comprised so that the output (applied voltage and applied current) each supplied to LED light source 3a-3d can be controlled separately.

  As described above, the lighting device 1 of the present embodiment includes the power supply circuit (DC-DC converter 11), the plurality of switching circuits 12a to 12d, and the control circuit 13. The power supply circuit supplies current to the plurality of LED light sources 3a to 3d that irradiate light to a common area. The plurality of switching circuits 12a to 12d switch between a state where current flows and a state where current does not flow for each of the plurality of LED light sources 3a to 3d. The control circuit 13 controls the plurality of switching circuits 12a to 12d to perform PWM control during a period in which a current flows through each of the plurality of LED light sources 3a to 3d. The control circuit 13 includes at least one of the plurality of LED light sources 3a to 3d other than the one LED light source in a second period including a first period in which one of the LED light sources 3a to 3d is turned off. Turn on the LED light source. Furthermore, the control circuit 13 controls the output of the power supply circuit so that the brightness of light emitted from the plurality of LED light sources 3a to 3d is constant over the entire period.

  Accordingly, since at least one LED light source other than the LED light source that is turned off is turned on in the second period including the first period in which one LED light source is turned off among the plurality of LED light sources 3a to 3d, all the LEDs are turned on. The situation where the light sources turn off at the same time is less likely to occur. In addition, since the control circuit 13 controls the output of the power supply circuit so that the brightness of light emitted from the plurality of LED light sources 3a to 3d is constant over the entire period, the temporal change in brightness Can be suppressed.

  Note that the control circuit 13 may control the output current of the power supply circuit so that the brightness of light emitted from the plurality of LED light sources 3a to 3d is constant over the entire period, or the output voltage of the power supply circuit. May be controlled. Since the brightness of the LED light source varies depending on the current value, the control circuit 13 controls the output current of the power supply circuit so that the brightness of light emitted from the plurality of LED light sources 3a to 3d is constant over the entire period. Is preferred.

  In the lighting device 1, it is also preferable that the control circuit 13 performs PWM control for each LED light source so that the number of LED light sources that are simultaneously turned on is constant. If the brightness of the plurality of LED light sources is the same, the brightness of the light emitted from the plurality of LED light sources 3a to 3d can be made constant over the entire period.

  In this lighting device 1, one switching circuit 12 a to 12 d may be connected to each of the plurality of LED light sources 3 a to 3 d connected in series between the output ends of the power supply circuit (DC-DC converter 11). When a failure occurs in any of the LED light sources 3a to 3d, the control circuit 13 may short-circuit the switching circuits 12a to 12d connected in parallel to the LED light sources 3a to 3d where the failure has occurred.

  Thereby, even when some of the plurality of LED light sources 3a to 3d are open broken due to a failure, it is possible to turn on LED light sources other than the open broken LED light source.

  As described above, the vehicular lighting device 20 of the present embodiment includes the above-described lighting device 1, a pair of main bodies 21 that hold the lighting device 1 and are respectively attached to the left and right sides of the vehicle body 51, and the pair of main bodies 21. And a plurality of LED light sources 3a to 3d that are held separately. The control circuit 13 held in each of the pair of main bodies 21 performs PWM control on the plurality of LED light sources 3a to 3d in synchronization with each other.

  The vehicle lighting device 20 according to the present embodiment includes the lighting device 1 according to the present embodiment, and the control circuit 13 performs PWM control on the LED light sources 3a to 3d that are separately held in the left and right main bodies 21, so that an output is provided. Temporal changes in light brightness can be suppressed.

  The vehicle lighting device 20 may further include one optical lens 4 that receives light emitted from each of the plurality of LED light sources 3a to 3d and controls light distribution of the incident LED light sources 3a to 3d. Good.

  Thereby, the light from the plurality of LED light sources 3a to 3d can be irradiated to the common area A1.

  Moreover, the vehicle 50 of this embodiment is provided with said lighting device 1, several LED light source 3a-3d, and the vehicle body 51 to which the lighting device 1 and several LED light source 3a-3d are attached.

  Since the vehicle 50 according to the present embodiment includes the lighting device 1 according to the present embodiment, the temporal change in the brightness of the output light can be reduced.

DESCRIPTION OF SYMBOLS 1 Lighting device 3a-3d LED light source 4 Optical lens 11 DC-DC converter (power supply circuit)
12a to 12d switching circuit 13 control circuit 20 lighting device for vehicle 21 main body 50 vehicle 51 vehicle body

Claims (6)

A power supply circuit for supplying current to a plurality of LED light sources that irradiate light to a common area;
A plurality of switching circuits for switching between a state in which current flows and a state in which current does not flow for each of the plurality of LED light sources;
A control circuit that performs PWM control of a period during which a current flows through each of the plurality of LED light sources by controlling the plurality of switching circuits;
The control circuit turns on at least one LED light source other than the one LED light source among the plurality of LED light sources in a second period including a first period during which one LED light source of the plurality of LED light sources is turned off. And a lighting device that controls the output of the power supply circuit so that the brightness of light emitted from the plurality of LED light sources is constant over the entire period.   The lighting device according to claim 1, wherein the control circuit performs PWM control for each of the LED light sources so that the number of the LED light sources that are simultaneously turned on is constant. One switching circuit is connected to each of the plurality of LED light sources connected in series between output terminals of the power supply circuit,
The said control circuit makes the said switching circuit connected in parallel with the said LED light source which the said malfunction generate | occur | produced in the short circuit state, when malfunction occurs in any of the said LED light sources. 2. The lighting device according to 2. The lighting device according to any one of claims 1 to 3, a pair of main bodies that hold the lighting device and are respectively attached to a left side and a right side of a vehicle body, and the plurality that are separately held by the pair of main bodies LED light source,
The vehicle lighting device, wherein the control circuits held in each of the pair of main bodies perform PWM control of the plurality of LED light sources in synchronization with each other.   The vehicle illumination device according to claim 4, further comprising one optical lens that receives light emitted from each of the plurality of LED light sources and controls light distribution of the plurality of LED light sources. .   A vehicle comprising the lighting device according to claim 1, the plurality of LED light sources, and a vehicle body that holds the lighting device and the plurality of LED light sources.

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