JP2009208764A - Vehicular light-emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve visibility in a front by irradiating the front by letting a light-emitting diode emit light with high brightness when traveling on a high-speed way at a high speed, and not to bedazzle a driver of an oncoming vehicle by reducing the brightness of the light-emitting diode when traveling on a two-way traffic road at a low speed. <P>SOLUTION: The vehicular light-emitting device 10 is equipped with the two or more light-emitting diodes 11 mounted on the vehicle, and a lighting circuit 12 for lighting these light-emitting diodes 11. The traveling speed of the vehicle is detected by a vehicle speed sensor 15, and the light circuit 12 is constituted so as to change the brightness of the light-emitting diodes 11 based on the detection output of a vehicle speed sensor 15. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light emitting device that emits light from a light emitting diode (LED) used as a headlight (headlight) or a daylight (daylight) of a vehicle.

  Conventionally, as a device of this type, a diode array forms a light source for a vehicle headlamp by connecting a large number of light emitting diodes in series, and a current control circuit supplies a diode array current that is fed from an in-vehicle power source and fed to the diode array. A vehicle headlamp device configured to control to a target value is disclosed (for example, see Patent Document 1). In this vehicle headlamp device, the voltage drop of the light emitting diode is detected by the voltage drop detecting circuit, and the light emitting diode short circuit detecting circuit determines whether or not the detected voltage drop is lower than a predetermined threshold voltage value. When it is lowered, it is determined that a short-circuit fault of the light emitting diode is detected, and a short-circuit fault detection signal for requesting a predetermined corresponding operation is output. In the vehicle headlamp device configured as described above, since the power supply current to the diode array is controlled to the target value, even if an on failure (short circuit failure) occurs in any one light emitting diode, the diode array As the load resistance decreases, the current increases and the voltage drop of the diode array does not increase. The voltage drop of the diode array decreases by one light emitting diode. As a result, it is possible to easily and accurately detect a short-circuit failure of the light emitting diodes constituting the diode array, and to maintain the energization current to the diode array at the target level regardless of the short-circuit failure. Further, by monitoring the voltage drop of the light emitting diode, an on failure of the light emitting diode can be detected.

JP 2007-186039 A (Claim 1, paragraph [0010])

  However, in the vehicle headlamp device disclosed in Patent Document 1 described above, if the luminance of the light emitting diodes constituting the diode array is too high, the light emitting diodes emit high power when traveling at low speed on a two-way street. There was a risk of dazzling the driver of the oncoming vehicle with the light of brightness. If the brightness of the light emitting diodes is lowered to eliminate this point, the brightness of the light emitting diodes may be insufficient when traveling on a highway at high speed, which may reduce the visibility in front of the vehicle. The object of the present invention is to improve forward visibility by illuminating the front by emitting a light emitting diode with high brightness when traveling on a highway at high speed, and when traveling on a two-way road at low speed Another object of the present invention is to provide a vehicle light emitting device that does not dazzle the driver of an oncoming vehicle by reducing the luminance of the light emitting diode.

  As shown in FIG. 1, the first aspect of the present invention is an improvement in a vehicle light-emitting device that includes two or more light-emitting diodes 11 mounted on a vehicle and a lighting circuit 12 that lights these light-emitting diodes 11. It is. The characteristic configuration is that the traveling speed of the vehicle is detected by the vehicle speed sensor 15, and the lighting circuit 12 is configured to change the luminance of the light emitting diode 11 based on the detection output of the vehicle speed sensor 15. In the vehicle light emitting device according to the first aspect, when the vehicle speed sensor 15 detects a vehicle speed equal to or higher than a predetermined value, the lighting circuit 12 increases the voltage applied to the light emitting diode 11 or increases the current flowing through the light emitting diode 11. Thus, the light emitting diode 11 emits light with high luminance. On the other hand, when the vehicle speed sensor 15 detects a vehicle speed lower than a predetermined value, the voltage applied to the light emitting diode 11 by the lighting circuit 12 is reduced or the current flowing through the light emitting diode 11 is reduced, thereby causing the light emitting diode 11 to emit light with low luminance. Let

  The second aspect of the present invention is the invention based on the first aspect, and when the vehicle speed sensor 15 detects a vehicle speed equal to or higher than a predetermined value within a range of 60 to 100 km / hour, as shown in FIG. In addition, when the lighting circuit 12 causes the light emitting diode 11 to emit light with 100% luminance and the vehicle speed sensor 15 detects a vehicle speed less than a predetermined value within a range of 60 to 100 km / hour, the lighting circuit 12 The luminance is reduced to 40 to 70%. In the vehicle light emitting device according to the second aspect, when the vehicle speed sensor 15 detects a vehicle speed equal to or higher than a predetermined value within the range of 60 to 100 km / hour, the lighting circuit 12 increases the voltage applied to the light emitting diode 11 or emits light. By increasing the current flowing through the diode 11, the light emitting diode 11 emits light with 100% luminance. On the other hand, when the vehicle speed sensor 15 detects a vehicle speed less than a predetermined value in the range of 60 to 100 km / hour, the lighting circuit 12 lowers the voltage applied to the light emitting diode 11 or reduces the current flowing through the light emitting diode 11. Then, the luminance of the light emitting diode 11 is reduced to 40 to 70% to emit light.

  The third aspect of the present invention is an invention based on the first or second aspect, and further, as shown in FIG. 1, the input terminal 12a of the lighting circuit 12 is connected to a battery having a DC voltage of 9 to 30V. The lighting circuit 12 converts the DC power input from the battery into pulse power of 30 kHz to 40 kHz, the smoothing circuit 14 that converts the pulse power converted by the switching regulator 13 into DC power, and the smoothing The voltage changing circuit 20 that changes the voltage of the DC power converted by the circuit 14 based on the detection output of the vehicle speed sensor 15, and the DC power that has been changed by the voltage changing circuit 20 and output from the smoothing circuit 14 are changed to 60. The pulse power output circuit 16 for converting to pulse power of ˜100 Hz, and the pulse power output from the pulse power output circuit 16 as its current Limiting resistor 17a which limit and outputs to the light emitting diode 11, and having an 17b.

  In the vehicle light emitting device according to the third aspect, when the vehicle speed sensor 15 detects a vehicle speed of a predetermined value or more in the range of 60 to 100 km / hour in advance, the detection output of the vehicle speed sensor 15 is the voltage change circuit of the lighting circuit 12. 20 is input. First, the switching regulator 13 of the lighting circuit 12 converts DC power input from the battery into pulse power of 30 kHz to 40 kHz. Next, the voltage of the pulse power is smoothed by the smoothing circuit 14 to obtain DC power. At this time, the voltage changing circuit 20 sets the voltage of the DC power converted by the smoothing circuit 14 to a predetermined value (100%) based on the detection output of the vehicle speed sensor 15. Next, the DC power of the predetermined voltage is converted by the pulse power output circuit 16 into pulse power of 60 to 100 Hz. Further, when the pulse power is output to the light emitting diode 11 by limiting the current by the limiting resistors 17a and 17b, the light emitting diode 11 emits light with 100% luminance. On the other hand, when the vehicle speed sensor 15 detects a vehicle speed less than a predetermined value within the range of 60 to 100 km / hour, the detection output of the vehicle speed sensor 15 is input to the voltage changing circuit 20 of the lighting circuit 12. First, DC power is converted into pulse power of 30 kHz to 40 kHz by the switching regulator 13 of the lighting circuit 12. Next, the voltage of the pulse power is smoothed by the smoothing circuit 14 to obtain DC power. At this time, the voltage changing circuit 20 drops the voltage of the DC power converted by the smoothing circuit 14 based on the detection output of the vehicle speed sensor 15. Next, the pulsed power output circuit 16 converts the DC power with this voltage dropped into pulsed power of 60 to 100 Hz. Further, when this pulse power is output to the light emitting diode 11 by limiting the current by the limiting resistors 17a and 17b, the light emitting diode 11 emits light with a luminance of 40 to 70%.

  In the vehicle light emitting device according to the first aspect, the vehicle speed sensor detects the traveling speed of the vehicle, and the lighting circuit changes the luminance of the light emitting diode based on the detection output of the vehicle speed sensor. When the above vehicle speed is detected, the voltage applied to the light emitting diode 11 by the lighting circuit is increased or the current flowing through the light emitting diode is increased, so that the light emitting diode emits light with high brightness, and the vehicle speed sensor reduces the vehicle speed below a predetermined value. When detected, the voltage applied to the light emitting diode 11 by the lighting circuit is reduced, or the current flowing through the light emitting diode is reduced to cause the light emitting diode to emit light with low luminance. As a result, when the vehicle is traveling at high speed on a highway that is not face-to-face, the light emitting diode emits light with high brightness, so that the visibility ahead of the vehicle can be improved and the vehicle is traveling on a face-to-face road at low speed. Since the light emitting diode emits light with low brightness, the driver of the oncoming vehicle is not dazzled.

  In the vehicle light-emitting device according to the second aspect, the lighting circuit causes the light-emitting diode to emit light with 100% luminance when the vehicle speed sensor detects a vehicle speed equal to or higher than a predetermined value within the range of 60 to 100 km / hour. When driving at high speed on a highway that is not face-to-face, the light-emitting diode emits light with high brightness, so the visibility ahead of the vehicle can be improved, and the vehicle speed sensor is less than a predetermined value in the range of 60 to 100 km / hour When the vehicle speed is detected, the lighting circuit reduces the brightness of the light-emitting diode to 40 to 70%. Therefore, when the vehicle is traveling on a two-way road at low speed, the light-emitting diode emits light with low brightness. , Do not dazzle oncoming drivers.

  In the vehicle light emitting device according to the third aspect, the switching regulator of the lighting circuit converts the DC power input from the battery having a DC voltage of 9 to 30 V into the pulse power of 30 kHz to 40 kHz, and the smoothing circuit converts the pulse power to the DC power. The voltage change circuit changes the voltage of the DC power based on the detection output of the vehicle speed sensor, and the pulse power output circuit converts the DC power output from the smoothing circuit after the voltage is changed by the voltage change circuit. When converted to 100 Hz pulse power, and further, the pulse power whose current is limited by the limiting resistor is output to the light emitting diode, the vehicle speed sensor detects a vehicle speed exceeding a predetermined value within the range of 60 to 100 km / hour. The lighting circuit causes the light emitting diode to emit light with 100% luminance, and the vehicle speed sensor detects a vehicle speed less than a predetermined value within a range of 60 to 100 km / hour. When issued, the lighting circuit reduces the brightness of the light emitting diodes 40 to 70%. As a result, the light-emitting diode emits light with high brightness when the vehicle is traveling on a highway that is not face-to-face, so the visibility ahead of the vehicle can be improved, and the vehicle travels on a face-to-face road at low speed. In this case, the light emitting diode emits light with low brightness, so that the driver of the oncoming vehicle is not dazzled.

It is a lighting circuit diagram of the light emitting device for automobiles of the first embodiment and Example 1 of the present invention. It is a circuit block diagram of the switching regulator of the light-emitting device. It is a circuit block diagram of the pulse power output circuit of the light emitting device. It is a figure which shows the phase difference of the pulse voltage and pulse current of the pulse electric power converted by the switching regulator. It is principal part sectional drawing containing the light emitting diode of the light-emitting device, a lens, and a heat radiating member. It is a figure which respectively shows the pulse current which flows into the S2 point of FIG. 1, and the pulse current which flows into the 1st and 2nd light emission part. It is a principal part top view of the motor vehicle which shows the state which used the light emitting diode as left and right daylight. It is a principal part top view of the motor vehicle corresponding to FIG. 7 which shows 2nd Embodiment of this invention. It is a lighting circuit diagram of the light-emitting device for motor vehicles of 3rd Embodiment of this invention. It is a lighting circuit diagram of the light-emitting device for motor vehicles of 4th Embodiment of this invention. It is a lighting circuit diagram of the light-emitting device for motor vehicles of 5th Embodiment of this invention. It is an oscilloscope photograph which shows the reason why the emitted-heat amount of a light emitting diode increases as the frequency of the pulse electric power output to a light emitting diode becomes high.

Next, an embodiment for carrying out the present invention will be described with reference to the drawings.
<First Embodiment>
As shown in FIGS. 1 and 7, twelve light emitting diodes 11 are mounted on an automobile 20, and the light emitting device 10 includes the light emitting diodes 11 and a lighting circuit 12 that lights these light emitting diodes 11. Of the twelve diodes 11, six light emitting diodes 11 constitute a first light emitting unit 11a, and the remaining six light emitting diodes 11 constitute a second light emitting unit 11b. In this embodiment, the first light emitting unit 11 a is used as the right daylight 20 a of the automobile 20, and the second light emitting unit 11 b is used as the left daylight 20 b of the automobile 20. The first and second light emitting units 11a and 11b are high output light emitting diodes having the same rated specifications. For example, white chip type LED: NCCW022S manufactured by Nichia Corporation is used. In FIG. 1, one light emitting diode is representatively shown as the first and second light emitting portions 11a and 11b. Further, in this embodiment, six light emitting diodes are connected to the lighting circuit as first and second light emitting units, respectively. However, one to two light emitting diodes are respectively used as first and second light emitting units. You may connect 7 or more at a time. When two or more light emitting diodes are respectively connected as the first and second light emitting units, these diodes may be connected in series or in parallel, or those connected in series may be further connected in parallel.

  The vehicle 20 (FIG. 7) is provided with a vehicle speed sensor 15 (FIG. 1) that detects the traveling speed of the vehicle 20. The lighting circuit 12 is configured to change the luminance of the light emitting diode based on the detection output of the vehicle speed sensor 15. Specifically, a battery (not shown) having a DC voltage of 9 to 30 V is connected to the input terminal 12 a of the lighting circuit 12. The lighting circuit 12 includes a switching regulator 13 that converts DC power input from the battery into pulse power of 30 kHz to 40 kHz, a smoothing circuit 14 that converts pulse power converted by the switching regulator 13 into DC power, and the DC power. The voltage change circuit 20 that changes the voltage of the vehicle based on the detection output of the vehicle speed sensor 15 and a pulse that converts the DC power output from the smoothing circuit 14 after the voltage is changed by the voltage change circuit 20 into pulse power of 60 to 100 Hz. The power output circuit 16 includes limiting resistors 17a and 17b that limit the current of the pulse power output from the pulse power output circuit 16 and output the current to the light emitting diode. Here, the DC voltage of the battery is limited to the range of 9 to 30V mainly for vehicles including not only automobiles 20 such as passenger cars and trucks but also self-propelled construction machines and self-propelled civil engineering machines. This is in consideration of the installed battery. Moreover, it is preferable that the input electric power of a battery is 5-15W.

  On the other hand, in this embodiment, the switching regulator 13 is accommodated in an 8-pin (terminal X1 to X8) SOP (Small Outline Package), and includes a reference voltage comparison block, an oscillation circuit block, and a switching block (see FIG. 2). Here, the eight terminals X1 to X8 of the switching regulator 13 shown in FIG. 2 correspond to the eight terminals X1 to X8 of the switching regulator 13 shown in FIG. In the reference voltage comparison block, the reference voltage is generated by the reference voltage generator 13a, the voltage comparator 13b detects whether the comparison voltage obtained by dividing the output voltage is lower or higher than the reference voltage, and the comparison voltage is higher than the reference voltage. If it is low, power is sent from the input, and if it is high, it is configured to suppress power to the output. In the oscillation circuit block, the output of the oscillator 13c is transmitted to the flip-flop 13d for switching control to drive the switching transistor 13e. Further, in the switching block, the switching transistor 13e is controlled by the output of the voltage comparator 13b and the output of the oscillator, and is configured to output pulse power having a frequency of 30 kHz to 40 kHz, preferably 36 kHz. The oscillator 13c detects the voltage of the overcurrent detection resistor 18 to suppress the oscillation operation in an overcurrent state to prevent the switching transistor 13e from being damaged, and one end is connected to the terminal X3 of the switching regulator 13. An oscillation frequency (switching frequency) can be changed by a timing capacitor 19 whose other end is grounded. The frequency of the pulse power is measured at the point S1 (FIG. 1) between the terminal X3 of the switching regulator 13 and the timing capacitor 19. Here, the reason why the frequency of the pulse power converted by the switching regulator 13 is limited to the range of 30 kHz to 40 kHz is to facilitate adjustment of the pulse width of the pulse power by the pulse power output circuit 16. The resistance value of the overcurrent detection resistor 18 is 0.2Ω in this embodiment, and the capacitance of the timing capacitor 19 is 1000 pF in this embodiment. Further, reference numeral 21 in FIG. 1 is an electrolytic capacitor having a capacitance of 100 μF, reference numeral 22 is a varistor (surge absorber), and reference numeral 23 is a diode. Furthermore, the phase difference between the pulse voltage and the pulse current of the pulse power converted by the switching regulator 13 can be set within a range of ± π / 2. In this embodiment, as shown in FIG. The phase is advanced by about π / 2 with respect to the sawtooth pulse voltage.

  The smoothing circuit 14 has a first resistor 14a having one end connected to the comparison voltage input of the voltage comparator 13b of the switching regulator 13 via the terminal X5 and the other end grounded via the smoothing capacitor 14d, and one end of the first resistor 14a. The second resistor 14b connected to the comparison voltage input of the voltage comparator 13b via the terminal X5, the third resistor 14c having one end connected to the second resistor 14b and the other end grounded, and one end switching A smoothing coil 14e connected to the emitter of the switching transistor 13e of the regulator 13 via the terminal X2 and the other end connected to the smoothing capacitor 14d, and one end connected to the emitter of the switching transistor 13e via the terminal X2 And a Schottky diode 14f whose end is grounded.

Although the resistance value R ₁ of the first resistor 14a is appropriately set from the relationship between the resistance value R ₃ of the resistance value R ₂ and the third resistor 14c of the second resistor 14b, 1.0kΩ~50.0kΩ Is preferably set within a range of 3.0 kΩ to 40.0 kΩ. The resistance value of the first resistor 14a R ₁ and the ratio R ₁ / R ₂ of the resistance value R ₂ of the second resistor 14b is from 5.4 to 6.2, preferably in the range of from 5.5 to 6.0 Set in. This is because as the output voltage V _B at the point B in FIG. 1 becomes in the range of 8.0～9.0V, to daylight 20a of the automobile 20, and 20b to emit light at a predetermined luminance. Here, the relationship between the output voltage V B at the point _B and the ratio R ₁ / R ₂ can be obtained from the equation V _B = [(R ₁ / R ₂ ) +1] × 1.25V. Furthermore the resistance of the first resistor 14a R ₁ and the second and third resistor 14b, the sum of the resistance values of 14c (R ₂ + R ₃₎ the ratio R ₁ / the (R ₂ + R ₃₎ is 4.4 to It is set within a range of 5.0, preferably 4.5 to 4.9. This is so that the output voltage V _B at the point B in FIG. 1 becomes in the range of 6.8～7.5V, 40 to 70 daylight 20a of the automobile 20, and 20b of the predetermined luminance (100%) %, Preferably at a luminance within the range of 40 to 60%. Here, the relationship between the output voltage V B at the point _B and the ratio R ₁ / (R ₂ + R ₃ ) is obtained from the formula V _B = [[R ₁ / (R ₂ + R ₃ )] + 1] × 1.25V. be able to. The smoothing capacitor 14d and the smoothing coil 14e are components of an LC circuit for smoothing the pulse power output from the switching regulator 13 into DC power. In this embodiment, the smoothing coil 14d Is set to 220 μH, and the capacitance of the smoothing capacitor 14 e is set to 220 μF.

  The voltage changing circuit 20 is configured to change whether or not to pass a current through the third resistor 14 c of the smoothing circuit 14 based on the output voltage detected by the vehicle speed sensor 15. The voltage changing circuit 20 includes a reference voltage generator 20a that generates a reference voltage, a voltage comparator 20b that compares an output voltage detected by the vehicle speed sensor 15 with a reference voltage generated by the reference voltage generator 20a, and a voltage comparator 20b. And a transistor 20c having a base connected to the output terminal. The collector of the transistor 20c is connected to a circuit connecting the second resistor 14b and the third resistor 14c of the smoothing circuit 14, and the emitter of the transistor 20c is grounded. When the vehicle speed sensor 15 detects a vehicle speed of a predetermined value or more within a range of 60 to 100 km / hour, preferably a predetermined value or more within a range of 70 to 90 km / hour, more preferably 80 km / hour or more, a reference voltage is detected. The detection output voltage higher than the reference voltage generated by the generator 20a is output to the voltage comparator 20b. At this time, since the voltage comparator 20b of the voltage changing circuit 20 passes a predetermined current through the base of the transistor 20c, the current flowing through the second resistor 14b of the smoothing circuit 14 does not flow through the third resistor 14c, and the current of the transistor 20c. By flowing between the collector and the emitter, the voltage of the DC power output from the smoothing circuit 14 is maintained at a predetermined value within the range of 8.0 to 9.0V. When the vehicle speed sensor 15 detects a vehicle speed of less than a predetermined value in the range of 60 to 100 km / hour, preferably less than a predetermined value in the range of 70 to 90 km / hour, more preferably less than 80 km / hour, the reference voltage The detection output voltage lower than the reference voltage generated by the generator 20a is output to the voltage comparator 20b. At this time, since the voltage comparator 20b of the voltage changing circuit 20 does not flow current to the base of the transistor 20c, no current flows between the collector and emitter of the transistor 20c, and the current flowing through the second resistor 14b of the smoothing circuit 14 By flowing through the third resistor 14c, the voltage of the DC power output from the smoothing circuit 14 drops below a predetermined value in the range of 6.8 to 7.5V.

  The pulse power output circuit 16 includes a timer 24 that outputs a pulse current of 60 to 100 Hz, first and second pulse width adjusting resistors 31 and 32 connected to the timer 24, and a pulse width connected to the timer 24. Based on the pulse current output from the adjustment capacitor 26, the timer 24 and the first and second light emitting units 11a and 11b and output from the timer 24, the first and second light emitting units 11a and 11b are alternately arranged. The first and second transistors 41 and 42 output first and second pulse powers that complement each other. In this embodiment, the timer 24 is configured by an IC called NE555 housed in an SOP (Small Outline Package) having 8 pins (terminals Y1 to Y8). Further, the eight terminals Y1 to Y8 of the timer 24 shown in FIG. 3 correspond to the eight terminals Y1 to Y8 of the timer 24 shown in FIG. The timer 24 includes first and second voltage comparators 24a and 24b, a flip-flop 24c, a discharging transistor 24d, and three resistors 24e, 24f, and 24g (FIG. 3). The three resistors 24e, 24f, and 24g are connected in series, and a pulse voltage (hereinafter referred to as Y8 voltage) applied to the terminal Y8 is divided into three. That is, 1/3 of the Y8 voltage is applied to the plus input terminal of the first voltage comparator 24a, and 2/3 of the Y8 voltage is applied to the minus terminal of the second voltage comparator 24b. Further, when the pulse voltage applied to the terminal Y2 (trigger) becomes 1/3 or less of the Y8 voltage, the S terminal of the flip-flop 24c becomes H level and the flip-flop 24c is set. Further, when the pulse voltage applied to the terminal Y6 (threshold) becomes 2/3 or more of the Y8 voltage, the R terminal of the flip-flop 24c becomes H level and the flip-flop 24c is set.

  On the other hand, the first pulse width adjusting resistor 31 is connected between the terminals Y4 and Y7 of the timer 24, and the second pulse width adjusting resistor 32 is connected between the terminals Y7 and Y2 of the timer. The One end of the pulse width adjusting capacitor 26 is connected to the terminal Y2 of the timer 24, and the other end is grounded. The base of the first transistor 41 is connected to the terminal Y3 of the timer 24 via the resistor 33, and the base of the second transistor 42 is connected to the terminal Y8 of the timer 24 via the resistors 36 and 34. The collector of the first transistor 41 is connected to the second light emitting unit 11b and connected to the circuit between the resistor 33 and the resistor 34, and the collector of the second transistor 42 is connected to the first light emitting unit 11a and the resistor. 33 and the resistor 34 are connected to a circuit. Furthermore, the emitter of the first transistor 41 and the emitter of the second transistor 42 are each grounded. When the pulse power output circuit 16 is configured as described above, a predetermined rectangular wave pulse current of 60 to 100 Hz, preferably 70 to 90 Hz, more preferably 80 Hz from the terminal Y3 of the timer 24 is generated between the base and the emitter of the first transistor. The first and second pulse powers complementing each other of 60 to 100 Hz, preferably 70 to 90 Hz, and more preferably 80 Hz are output to the first and second light emitting units 11a and 11b, respectively. Here, the frequency of the first and second pulse power output from the pulse power output circuit 16 is limited to the range of 60 to 100 Hz because the light emitted from the first and second light emitting units 11a and 11b is less than 60 Hz. This is because the effect of suppressing the heat generation of the first and second light emitting units 11a and 11b is reduced when the frequency exceeds 100 Hz.

  On the other hand, the “New Occupational Health Handbook” (issued by Labor Science Laboratories, hereinafter referred to as “Reference 1”), page 643, left column, lines 4-6, “intermittent light, it is continuous The flicker value (flicker value) indicates the discriminative threshold value at the boundary between visible light and intermittent light as the number of intermittent times (Hz) at that time. Is described. From the bottom line of the left column of page 643 of the above-mentioned document 1 to the 8th line to the 7th line from the bottom, "The light intermittent frequency is smoothly changed at a speed of about 1 Hz per second in the range of 20 to 50 Hz, and the blink ratio is 1 : 1. Is described. In addition, “IC-portable” on the left column of page 54 of “Prototype of portable flicker measuring instrument” (Occupational Medicine Vol. 22, Jap. J. Ind. Health, Vol. 22, 1980, hereinafter referred to as Reference 2). In the second to eighth lines of the “flicker measuring device block diagram”, “In the block diagram, the 27-55 Hz oscillator generates a rectangular wave of 27-55 Hz and produces a flickering reference frequency. The frequency adjuster is the part that changes the frequency of the oscillator, and the variable resistor is included in the circuit. This is linked with the frequency change knob (2). The central light source driving circuit causes the light emitting diode of the flicker target to blink at a blinking ratio of 1: 1 by a rectangular wave from the oscillator. Is described. On the vertical axis of the graph in Fig. 3 on page 55, left column of Reference 2, the Flicker value is scaled in the range of 42 to 50 Hz. Page 55, right column, lines 4 to 5 In the eyes, “The average flicker value was 44.9 Hz, and the limit values of the individual values were 42.0 Hz and 47.6 Hz. Is described. In addition, the horizontal axis of the graph in Fig. 5-10 on page 70 of "Fundamental study on aging and fatigue of persons with disabilities" (published by Japan Association for Employment Promotion of Persons with Disabilities, hereinafter referred to as Reference 3) On the vertical axis, flicker values before and after the work are graduated in the range of 30 to 46 c / s (Hz). On page 68, line 20 to line 27, When the above-mentioned flicker values before and after work are divided into two groups, the 17-30 year old group and the 55-69 year old group, the characteristics are as follows. When looking at the relationship between before and after work, the flicker value is lower than that of young people aged 17 to 30 years before and after work, and when fatigue is significant, there is a deviation toward the origin on the graph As expected, both young and old It can be seen that not been the kind of distribution of. Looking at the variance of the flicker value between the younger age group and the older age group, it can be seen that it is larger in the older age group than in the younger age group. Is described. Further, the vertical axis of the graph of FIG. 8 on page 90 of “Fatigue awareness and change in flicker value during cooking process” (hereinafter referred to as Document 4) is a scale in the range of 31 to 37. Here, although the unit is not described on the vertical axis of FIG. 8 of Reference 4, the definition of the flicker value is “the boundary between whether light is interrupted and viewed as continuous light or intermittent light. The flicker value (flicker value) indicates the discrimination threshold value in terms of the number of interruptions (Hz) at that time. ], It is considered that the unit of the flicker values 31 to 37 on the vertical axis in FIG. 8 of Document 4 is “Hz”. In the left column of page 90, line 7 to line 12 of the document 4, “Comparison of flicker values according to sleep time on the previous night is shown in FIG. In the first training, the group with less sleep was significantly lower than the group with more sleep. Although it was not statistically significant in the second practice, there was a tendency to take a low value when sleep time was short. Is described. As is clear from the above-mentioned documents 1 to 4, the maximum flicker value of the flicker measuring device is 55 Hz, and the flicker value (flicker value) is 55 Hz or less even in a young age group who has taken enough sleep. . Therefore, if the frequency of the first and second pulse powers output from the pulse power output circuit 16 is set to 60 Hz or more, even a younger age group who sufficiently sleeps does not feel “flicker”.

  When the frequency of the first and second pulse powers output from the pulse power output circuit 16 is adjusted to 80 Hz, the resistance values of the first and second pulse width adjusting resistors 31 and 32 are 1 kΩ and It is set to 91 kΩ, and the capacitance of the pulse width adjusting capacitor 26 is adjusted to 0.1 μF. The capacitance of the capacitor 27 whose one end is connected to Y5 of the timer 24 and whose other end is grounded is set to 0.1 μF, and the resistance values of the resistors 33, 34, and 36 are 2 kΩ, 1.5 kΩ, and 1.5 kΩ. Respectively. Further, the duty ratio of the first and second pulse powers output from the pulse power output circuit 16 is set to 50%. Here, the duty ratio refers to a value representing the ratio of the width on the high pulse side to the width of one cycle of the first and second pulse powers output from the pulse power output circuit 16 as a percentage. The anode of the first light emitting unit 11a is connected to the terminal Y8 of the timer 24, the cathode of the first light emitting unit 11a is connected to the collector of the second transistor 42 via the first limiting resistor 17a, and the second light emitting unit 11b. Is connected to the terminal Y8 of the timer 24, and the cathode of the second light emitting unit 11b is connected to the collector of the second transistor 42 via the second limiting resistor 17b. The resistance values of the first and second limiting resistors 17a and 17b are set to 1.0Ω to 100.0Ω, preferably 1.0Ω to 40.0Ω, respectively. Here, the resistance values of the first and second limiting resistors 17a and 17b are limited to the range of 1.0Ω to 100.0Ω, respectively. This is because current flows and the heat generation amount of the first and second light emitting units becomes excessive, and if it exceeds 100.0Ω, the heat generation amount of the first and second limiting resistors themselves becomes excessive.

  As shown in FIG. 5, the first and second light emitting portions 11 a and 11 b are attached to the base portion 11 c containing the light emitting element, the first lens 11 d attached to the surface of the base portion 11 c, and the back surface of the base portion 11 c. Each has a first heat radiating member 11e. The 1st and 2nd light emission parts 11a and 11b are attached to the 2nd heat radiating member 52, respectively. The second heat radiating member 52 includes a large-diameter portion 52a formed in a large-diameter columnar shape and a small-diameter portion 52b formed in a columnar shape having a smaller diameter than the large-diameter portion 52a. A plurality of heat radiating grooves 52c extending in the center line direction of the large diameter portion 52a are formed on the outer peripheral surface of the large diameter portion 52a at a predetermined interval, and the first and second light emitting portions 11a and 11b are formed in the small diameter portion 52b. Recesses 52d are respectively formed. After the first and second light emitting portions 11a and 11b are inserted into the recesses 52d, the transparent acrylic second lens 62 is fitted into the small diameter portion 52b. The large-diameter portion 52 a of the second heat radiating member 52 is inserted into the hole 53 a of the base member 53. The holes 53a are formed in the base member 53 by the number of the first and second light emitting portions 11a and 11b with a predetermined interval. As the first heat radiating member 11e, a metal plate having good thermal conductivity such as an alumite-treated aluminum plate is used, and the second heat radiating member 52 and the base member 53 can be formed of a high thermal conductive resin. As this highly heat conductive resin, it is preferable to use PP (polypropylene) and PA6 (Polyamide 6) filled with a filler mainly composed of graphite powder. Further, immediately before the large-diameter portion 52a of the second heat radiating member 52 is inserted into the hole 53a of the base member 53, methyl chloride is applied to one or both of the outer peripheral surface of the large-diameter portion 52a and the inner peripheral surface of the hole. It is preferable. This is because the second heat radiating member 52 and the base member 53 are bonded by a chemical polymerization reaction of methyl chloride, and after this bonding, the methyl chloride evaporates. Thermal conductivity does not decrease. As a result, there is an effect that the heat generated by the first and second light emitting portions 11a and 11b is smoothly transmitted and dissipated through the bonding portion of the second heat radiating member 52 and the base member 53. Note that chromium plating or the like (metal plating on the resin surface) is applied to the outer peripheral surface of the second heat dissipation member 52 including the inside of the heat dissipation groove 52c, and chromium plating or the like (resin is applied to the entire surface of the base member 53 including the inner peripheral surface of the hole 53a. After the metal plating on the surface), the large diameter portion 52a of the second heat radiating member 52 may be inserted into the hole 53a of the base member 53. In this case, the thermal conductivity of the contact portion between the large-diameter portion 52a and the base member 53 does not decrease, but rather the thermal conductivity is improved. Therefore, the heat generated by the first and second light emitting portions 11a and 11b is the second heat radiation. There is an effect that the contact portion between the member 52 and the base member 53 is smoothly transmitted and diffused. In this case, the second heat radiating member 52 is fixed to the base member 53 using a band, a screw or the like without using methyl chloride.

  The operation of the light emitting device 10 configured as described above will be described. First, DC power (for example, voltage 12V) output from the battery is input to the switching regulator 13 from the input terminal 12a of the lighting circuit 12, and is converted into pulse power of 30 kHz to 40 kHz by the switching regulator 13. Next, the voltage of the pulse power is smoothed by the smoothing circuit 14 to become DC power, and the voltage of the DC power is lowered to 5 to 12V. Specifically, the pulse power output from the switching regulator 13 is smoothed by the smoothing circuit 14 and converted to DC power. The voltage of the DC power is between the first and second resistors 14a and 14b. The circuit feeds back to the terminal X5 of the switching regulator 13. When the voltage of the fed back DC power is higher than the set DC power voltage (for example, 8.5V), the switching regulator 13 widens the interval of the pulse wave of the pulse power and outputs it to the smoothing circuit 14. When the voltage of the fed back DC power is lower than the set DC power voltage (for example, 8.5 V), the switching regulator 13 narrows the interval of the pulse wave of the pulse power and outputs it to the smoothing circuit 14. Thus, the voltage of the DC power output from the smoothing circuit 14 to the pulse power output circuit 16 is kept constant. However, when the traveling speed of the automobile 20 is not less than a predetermined value in the range of 60 to 100 km / hour (for example, not less than 80 km / hour), the vehicle speed sensor 15 detects higher than the reference voltage generated by the reference voltage generator 20a. The output voltage is output to the voltage comparator 20b. At this time, since the voltage comparator 20b of the voltage changing circuit 20 passes a predetermined current through the base of the transistor 20c, the current flowing through the second resistor 14b of the smoothing circuit 14 does not flow through the third resistor 14c, and the current of the transistor 20c. By flowing between the collector and the emitter, the voltage of the DC power output from the smoothing circuit 14 is maintained at 8.5V, for example.

The DC power output from the smoothing circuit 14 is output to the first and second light emitting units alternately as first and second pulse powers that are 60-100 Hz pulse power complemented by the pulse power output circuit 16. The Specifically, a rectangular wave pulse current shown in FIG. 6A flows between the terminal Y3 of the timer 24 and the base and emitter of the first transistor 41 (this current is a current measured at point S2 in FIG. 1). .) While rectangular-shaped pulse current flows between the base and the emitter of the first transistor 41, i.e., between the T ₁ sec FIG. 6 (a), between the collector and the emitter of the first transistor 41 is large current, resistance It flows through the circuit provided with the device 34 and the circuit provided with the second light emitting unit 11b and the second limiting resistor 17b. For this reason, since a relatively large current flows through the second light emitting unit 11b, the second light emitting unit 11b emits light and is lit. However, since no current flows between the base and the emitter of the second transistor 42 at this time, no current flows between the collector and the emitter of the second transistor 42, and the first light emitting unit 11a does not emit light and is turned off. . On the other hand, no current flows between the collector and the emitter of the first transistor 41 during a period of T ₂ seconds in FIG. 6A during which no rectangular wave-shaped pulse current flows between the base and the emitter of the first transistor 41. . For this reason, since no current flows through the second light emitting unit 11b, the second light emitting unit 11b does not emit light and is turned off. However, since a current flows between the base and emitter of the second transistor 42 through the resistors 34 and 36 at this time, a large current flows between the collector and emitter of the first transistor 41. For this reason, since a comparatively large electric current flows into the 1st light emission part 11a, the 1st light emission part 11a light-emits and lights.

Accordingly, since the voltage of the pulse power applied alternately to the first and second light emitting units 11a and 11b is as high as 8.5 V, for example, the current flowing through the first and second light emitting units 11a and 11b increases, and the first And the 2nd light emission part 11a, 11b can be light-emitted by high-intensity. As a result, when the automobile 20 is traveling at a high speed (for example, 80 km / hour or more) on a highway that is not face-to-face, the first and second light emitting units 11a and 11b emit light with high brightness. Visibility can be improved. The current flowing through the first light emitting unit 11a is a rectangular wave-shaped pulse current as shown in FIG. 6C, and the current flowing through the second light emitting unit 11b is a rectangular wave-shaped pulse current as shown in FIG. 6B. Thus, T ₁ seconds and T ₂ seconds in FIG. 6A are the same.

  In addition, compared with the case where DC power is output to the first and second light emitting units 11a and 11b, the light emitted from the first and second light emitting units 11a and 11b is visible to the eyes as continuous light instead of discontinuous light. And the heat_generation | fever of 2nd light emission part 11a, 11b can be suppressed. Further, when the pulse voltage output from the lighting circuit 12 is the same as compared with the case where 60 to 100 Hz pulse power is simultaneously output to the first and second light emitting units 11a and 11b, the pulse current output from the lighting circuit 12 is the same. Therefore, if the pulse current output from the lighting circuit 12 is the same, the pulse voltage output from the lighting circuit 12 can be increased, so that the first and second light emitting portions 11a can be reduced. , 11b can be increased. Further, when pulse power of 60 to 100 Hz is simultaneously output to the first and second light emitting units 11a and 11b in a state where the number of connected light emitting diodes in the first and second light emitting units 11a and 11b is increased, these light emitting units. Since the power required by 11a and 11b may be limited by the switching regulator 13, the current flowing through each light emitting section 11a and 11b decreases, and the luminance of each light emitting section 11a and 11b decreases. On the other hand, in the present invention, even if the number of connected light emitting diodes in the first and second light emitting units 11a and 11b is increased, the power required by these light emitting units 11a and 11b is less likely to be limited by the switching regulator 13. The current flowing through each light emitting part 11a, 11b does not decrease and the brightness of each light emitting part 11a, 11b decreases. That's can be prevented. From the above, even if the voltage of the DC power input to the lighting circuit 12 is not constant and unstable, the lighting circuit 12 alternately supplies stable pulse power to the first and second light emitting units 11a and 11b. Therefore, the first and second light emitting units 11a and 11b can be set to a predetermined range without reducing the light amounts of the first and second light emitting units 11a and 11b and without overheating the first and second light emitting units 11a and 11b. Light can be emitted with luminance.

  On the other hand, when the traveling speed of the automobile 20 is less than a predetermined value within the range of 60 to 100 km / hour (for example, less than 80 km / hour), the vehicle speed sensor 15 detects lower than the reference voltage generated by the reference voltage generator 20a. The output voltage is output to the voltage comparator 20b. At this time, since the voltage comparator 20b of the voltage changing circuit 20 does not flow current to the base of the transistor 20c, no current flows between the collector and emitter of the transistor 20c, and the current flowing through the second resistor 14b of the smoothing circuit 14 By flowing through the third resistor 14c, the voltage of the DC power output from the smoothing circuit 14 is reduced to, for example, 7.5V. Accordingly, since the voltage of the pulse power applied alternately to the first and second light emitting units 11a and 11b is reduced to, for example, 7.5 V, the current flowing through the first and second light emitting units 11a and 11b decreases, and the first The luminance of the first and second light emitting units 11a and 11b is reduced to 40 to 70%. As a result, when the vehicle 20 is traveling on a two-way road at a low speed (for example, less than 80 km / hour), the first and second light emitting units 11a and 11b emit light with low luminance, so that the driver of the oncoming vehicle Will not dazzle you.

<Second Embodiment>
FIG. 8 shows a second embodiment of the present invention. In FIG. 8, the same reference numerals as those in FIG. 7 denote the same components. In this embodiment, the first and second light emitting portions 61a and 61b are each composed of a plurality of light emitting diodes 11, and the first light emitting portion 61a is a part of the right daylight 20a and the left daylight 20b of the automobile 20, respectively. The second light emitting unit 61b is used as the remaining part of the right daylight 20a and the left daylight 20b of the automobile 20. Specifically, six light emitting diodes 11 are used for the right daylight 20a of the automobile 20, and six diodes are used for the left daylight 20b. The first light emitting unit 61a includes three light emitting diodes 11 used for the right daylight 20a of the automobile 20 and three light emitting diodes 11 used for the left daylight 20b. The light emitting unit 61b includes three light emitting diodes used for the right daylight 20a of the automobile 20 and three light emitting diodes used for the left daylight 20b. The configuration other than the above is the same as that of the first embodiment. In the light emitting device configured as described above, the left and right daylights of the automobile emit light more evenly than the daylight of the first embodiment. Since operations other than those described above are substantially the same as those in the first embodiment, repeated description will be omitted.

<Third Embodiment>
FIG. 9 shows an automobile light emitting device 80 according to a third embodiment of the present invention. The light emitting device 80 is a large number (for example, 7 or more) of first and second light emitting units 11a and 11b. It is suitable for automobile daylights and headlights when it is necessary to increase the voltage from the battery using each light emitting diode. However, in FIG. 9, one light emitting diode is representatively shown as the first and second light emitting portions 11a and 11b. 9, the same reference numerals as those in FIG. 1 denote the same parts. Since the switching regulator 13 of this embodiment is the same as the switching regulator of the first embodiment, FIG. 2 used in the first embodiment is used as it is in the description of this embodiment. In this embodiment, the smoothing circuit 84 converts the pulse power converted by the switching regulator 13 into DC power and raises the voltage from the voltage of the input DC power, and the pulse power output circuit 16 performs the smoothing circuit. The direct-current power boosted at 84 is configured to output pulse power of 60 to 100 Hz as first and second pulse powers that complement each other. The smoothing circuit 84 has an amplification coil 84d connected between the terminal X1 and the terminal X8 of the switching regulator 13, one end connected to the amplification coil 84d, and the other end connected to the first to third resistors 84a to 84c. And a smoothing capacitor 84f having one end connected to the Schottky diode 84e and the other end grounded. One end of the amplifying coil 84d is connected to one collector of the two switching transistors 13e and 13e of the switching regulator 13 via a resistor 84g and a terminal X8, and the other end of the amplifying coil 84d is connected to two terminals via a terminal X1. It is connected to the other collector of the switching transistors 13e, 13e (FIGS. 2 and 9). The resistance value R ₁ of the first resistor 84a is set to 46 kΩ, for example, the resistance value R ₂ of the second resistor 84b is set to ₂ kΩ, and the resistance value R ₃ of the third resistor 84c is 0.3 kΩ, for example. The resistance value of the resistor 84f is set to 180Ω, for example. As a result, the ratio R ₁ / R ₂ becomes 23, and the output voltage V _{B at} point B in FIG. 9 becomes 30 V from the relational expression V _B = [(R ₁ / R ₂ ) +1] × 1.25V. The ratio R ₁ / (R ₂ + R ₃ ) is 20, and the output voltage V B at the point _B is about 26 V from the relational expression V _B = [[R ₁ / (R ₂ + R ₃ )] + 1] × 1.25V. It becomes.

  The amplifying coil 84d is provided for amplifying the voltage of the pulse power converted by the switching regulator 13, and the Schottky diode 84e is provided for rectifying the pulse power obtained by amplifying the voltage, and the smoothing capacitor 84f. Is provided for smoothing the rectified pulse power into DC power. A DC power supply of the battery is connected to the input terminal 12a of the lighting circuit 82, and its DC voltage is set to 14V, for example. The inductance of the amplifying coil 84d is set to 180 μH, for example, and the capacitance of the smoothing capacitor 84f is set to 150 μF, for example. Further, the resistance value of the overcurrent detection resistor 18 is set to 0.22Ω, for example, and the capacitance of the timing capacitor 19 is set to 1500 pF, for example. Assuming that the DC voltage input from the DC power supply is 14V as described above, the voltage of the DC power that has been converted to pulse power of 30 kHz to 40 kHz by the switching regulator 13 and then smoothed by the smoothing circuit 84 rises to 30V. The voltage changing circuit 20 has the same configuration as that of the first embodiment, and the collector of the transistor 20c of the voltage changing circuit 20 connects the second resistor 84b and the third resistor 84c of the smoothing circuit 84. Connected to the circuit. The configuration other than the above is the same as that of the first embodiment.

  The operation of the light emitting device 80 configured as described above will be described. First, DC power (for example, voltage 14V) output from the battery is input to the switching regulator 13 from the input terminal 12a of the lighting circuit 82, and is converted into pulse power of 30 kHz to 40 kHz by the switching regulator 13. Next, the voltage of the pulse power is smoothed by the smoothing circuit 84 to be converted to DC power, and the voltage of the DC power is boosted to, for example, 30V. Specifically, the voltage of the pulse power converted by the switching regulator 13 is amplified by the amplifying coil 84d, the pulse power obtained by amplifying the voltage is rectified by the Schottky diode 84e, and the rectified pulse power is Smoothing is performed by the smoothing capacitor 84f. The smoothed DC power voltage is higher than the input DC power voltage. The smoothed DC power voltage is fed back to the terminal X5 of the switching regulator 13 from the circuit between the first and second resistors 14a and 14b. When the voltage of the fed back DC power is higher than the set DC power voltage (30V), the switching regulator 13 widens the interval of the pulse wave of the pulse power and outputs the pulse power to the smoothing circuit 84 for feedback. When the voltage of the DC power is lower than the set voltage (30V) of the DC power, the switching regulator 13 narrows the interval between the pulse waves of the pulse power and outputs the pulse power to the smoothing circuit 84, whereby the pulse from the smoothing circuit 84 is output. The voltage of the DC power output to the power output circuit 16 is kept constant.

  However, when the traveling speed of the automobile is not less than a predetermined value in the range of 60 to 100 km / hour (for example, not less than 80 km / hour), the vehicle speed sensor 15 has a detection output higher than the reference voltage generated by the reference voltage generator 20a. The voltage is output to the voltage comparator 20b. At this time, since the voltage comparator 20b of the voltage changing circuit 20 passes a predetermined current through the base of the transistor 20c, the current flowing through the second resistor 84b of the smoothing circuit 84 does not flow through the third resistor 84c, and the current of the transistor 20c. By flowing between the collector and the emitter, the voltage of the DC power output from the smoothing circuit 84 is maintained at 30V. The DC power output from the smoothing circuit 14 is pulse power of 60 to 100 Hz by the pulse power output circuit 16 and is alternately supplied to the first and second light emitting units 11a and 11b as first and second pulse powers that complement each other. Is output. Therefore, since the voltage of the pulse power applied alternately to the first and second light emitting units 11a and 11b is as high as 5 to 12V, the current flowing through the first and second light emitting units 11a and 11b increases, The second light emitting units 11a and 11b can emit light with high luminance. As a result, the first and second light emitting units 11a and 11b emit light with high brightness when the vehicle is traveling at a high speed (for example, 80 km / hour or more) on a highway where the vehicle is not facing traffic. Can be improved.

  On the other hand, when the traveling speed of the automobile is less than a predetermined value within the range of 60 to 100 km / hour (for example, less than 80 km / hour), the vehicle speed sensor 15 has a detection output lower than the reference voltage generated by the reference voltage generator 20a. The voltage is output to the voltage comparator 20b. At this time, since the voltage comparator 20b of the voltage changing circuit 20 does not flow current to the base of the transistor 20c, no current flows between the collector and emitter of the transistor 20c, and the current flowing through the second resistor 84b of the smoothing circuit 84 is By flowing through the third resistor 84c, the voltage of the DC power output from the smoothing circuit 84 drops from 30V. Accordingly, since the voltage of the pulse power applied alternately to the first and second light emitting units 11a and 11b is lower than 30V, the current flowing through the first and second light emitting units 11a and 11b is reduced, and the first and second light emitting units 11a and 11b are reduced. The luminance of the two light emitting units 11a and 11b is reduced to 40 to 70%. As a result, when the vehicle is traveling on a two-way road at a low speed (for example, less than 80 km / hour), the light emitting diode emits light with low brightness, so that the driver of the oncoming vehicle is not dazzled. Since operations other than those described above are substantially the same as those in the first embodiment, repeated description will be omitted.

  In the first to third embodiments, pulse power is alternately output to the first and second light emitting units. However, the pulse power output of the lighting circuit 102 of the automotive light emitting device 100 as shown in FIG. By using the circuit 106, that is, the pulse power output circuit 106 excluding the second transistor 42 and the resistors 34 and 36 of the third embodiment, pulse power is simultaneously output to the first and second light emitting units 11a and 11b. Alternatively, the pulse power output circuit 106 of the lighting circuit 122 of the automobile light emitting device 120 as shown in FIG. 11, that is, the pulse power excluding the second transistor 42 and the resistors 34 and 36 of the first embodiment may be used. Using the output circuit 106, pulse power may be simultaneously output to the first and second light emitting units 11a and 11b. In the first to third embodiments, the lighting circuit includes a switching regulator, a smoothing circuit, a voltage changing circuit, a pulse power output circuit, and a limiting resistor, but outputs to the first and second light emitting units. If the voltage of the first and second pulse powers is always a predetermined value and does not fluctuate, the switching regulator and the smoothing circuit are not required, and the lighting circuit is constituted by a voltage changing circuit, a pulse power output circuit, and a limiting resistor. May be. In this case, the voltage changing circuit is configured to maintain or drop the voltage of the input DC power.

Next, examples of the present invention will be described in detail together with comparative examples.
<Example 1>
As shown in FIG. 1, the light emitting device 10 is configured by connecting the first and second light emitting units 11 a and 11 b to the lighting circuit 12. In FIG. 1, one each of the first and second light emitting units 11 a and 11 b are connected to the lighting circuit 12, but here, the first light emitting unit 11 a (light emitting diode) is arranged in parallel one by three. A total of three second light emitting units 11b (light emitting diodes) were connected in parallel one by one. Further, NJM2360 manufactured by New Japan Radio Co., Ltd. was used as the switching regulator 13. Further, the voltage changing circuit 20 of FIG. 1 was not connected. On the other hand, the resistance value of the overcurrent detection resistor 18 in the lighting circuit 12 is set to 0.2Ω, the capacitance of the timing capacitor 19 is set to 1 nF, the capacitance of the electrolytic capacitor 21 is set to 100 μF, and the first resistor 14a The resistance value was 7.5 kΩ, the resistance value of the second resistor 14 b was 1.3 kΩ, the inductance of the smoothing coil 14 e was 220 μH, and the capacitance of the smoothing capacitor 14 d was 220 μF. Resistance of the first resistor 14a R ₁ and the ratio R ₁ / R ₂ of the resistance value R ₂ of the second resistor 14b was about 6.8. The third resistor 14c was not connected, and the other end of the second resistor 14b was grounded.

  The resistance value of the first pulse width adjusting resistor 31 in the lighting circuit 12 is 1 kΩ, the resistance value of the second pulse width adjusting resistor 32 is 91 kΩ, and the capacitance of the pulse width adjusting capacitor 26 is 0. 0.1 μF, the capacitance of the capacitor 27 is 0.1 μF, the resistance value of the resistor 33 is 2 kΩ, the resistance value of the resistor 34 is 1.5 kΩ, and the resistance value of the resistor 36 is 1.5 kΩ, The duty ratio of the first and second pulse powers output from the pulse power output circuit 16 is 50%. Further, the resistance value of the first limiting resistor 17a in the lighting circuit 12 is set to 2.2Ω, and the resistance value of the second limiting resistor 17b is set to 2.2Ω. In addition, the 2nd heat radiating member 52 which attaches the 1st and 2nd light emission parts 11a and 11b, and the base member 53 which attaches the 2nd heat radiating member 52 used ABS resin instead of highly heat conductive resin (FIG. 5). This light-emitting device 10 was taken as Example 1. In the light emitting device 10 of Example 1, an 80 Hz rectangular wave pulse current flowed from the terminal Y3 of the pulse power output circuit 16.

<Example 2>
The light emitting device was configured in the same manner as in Example 1 except that the third resistor 14c having a resistance value of 0.2 kΩ was connected to the other end of the second resistor 14b. This light-emitting device was referred to as Example 2. The ratio R ₁ / (R ₂ + R ₃ ) between the resistance value R ₁ of the first resistor 14a and the total resistance value (R ₂ + R ₃ ) of the second and third resistors 14b and 14c is 6.0. there were.

<Comparative test 1 and evaluation>
The illuminance of the light emitting diodes when the light emitting diodes were turned on by the light emitting devices of Examples 1 and 2 was measured. The results are shown in Table 1 together with the DC voltage input to the lighting circuit and the output voltage and frequency output to the first and second light emitting units.

As is clear from Table 1, in Example 1, the illuminance of the light emitting diode was as high as 280 lux, whereas in Example 2, the illuminance of the light emitting diode was as low as 190 lux. As a result, the illuminance of the light emitting diode of Example 2 was reduced to about 68% when the illuminance of the light emitting diode of Example 1 was 100%. Therefore, when the vehicle speed sensor detects a vehicle speed of a predetermined value or higher, the lighting circuit is switched to increase the voltage applied to the light emitting diode as in the first embodiment, so that the light emitting diode emits light with high brightness, and the vehicle speed is increased. When the sensor detects a vehicle speed less than a predetermined value, the lighting circuit can be switched to lower the voltage applied to the light emitting diode as in the second embodiment, so that the light emitting diode can emit light with low luminance.

<Example 3>
As shown in FIG. 5, a light emitting diode 11 (white chip type LED: NCCW022S manufactured by Nichia Corporation) is prepared, the light emitting diode 11 is attached to a second heat radiating member 42, and the second heat radiating member 42 is a base member. 43. The base member 43 is made of an ABS resin instead of a high thermal conductive resin. In this state, pulse power having a frequency of 60 Hz was output to the light emitting diode 11 through a limiting resistor. The pulse voltage of this pulse power was 1.6V. This circuit is referred to as Example 3.
<Example 4>
A circuit was configured in the same manner as in Example 3 except that the frequency of the pulse power output to the light emitting diode was 65 Hz. This circuit was referred to as Example 4.
<Example 5>
A circuit was configured in the same manner as in Example 3 except that the frequency of the pulse power output to the light emitting diode was set to 70 Hz. This circuit was referred to as Example 5.
<Example 6>
A circuit was configured in the same manner as in Example 3 except that the frequency of the pulse power output to the light emitting diode was 80 Hz. This circuit was referred to as Example 6.
<Example 7>
A circuit was configured in the same manner as in Example 3 except that the frequency of the pulse power output to the light emitting diode was 90 Hz. This circuit was referred to as Example 7.
<Example 8>
A circuit was configured in the same manner as in Example 3 except that the frequency of the pulse power output to the light emitting diode was 95 Hz. This circuit was referred to as Example 8.
<Example 9>
A circuit was configured in the same manner as in Example 3 except that the frequency of the pulse power output to the light emitting diode was set to 100 Hz. This circuit was referred to as Example 9.

<Comparative Example 1>
A circuit was configured in the same manner as in Example 3 except that the frequency of the pulse power output to the light emitting diode was 40 Hz. This circuit was referred to as Comparative Example 1.
<Comparative Example 2>
A circuit was configured in the same manner as in Example 3 except that the frequency of the pulse power output to the light emitting diode was 50 Hz. This circuit was referred to as Comparative Example 2.
<Comparative Example 3>
A circuit was configured in the same manner as in Example 3 except that the frequency of the pulse power output to the light emitting diode was 55 Hz. This circuit was referred to as Comparative Example 3.
<Comparative example 4>
A circuit was configured in the same manner as in Example 3 except that the frequency of the pulse power output to the light emitting diode was 120 Hz. This circuit was referred to as Comparative Example 4.
<Comparative Example 5>
A circuit was configured in the same manner as in Example 3 except that the frequency of the pulse power output to the light emitting diode was 140 Hz. This circuit was referred to as Comparative Example 5.
<Comparative Example 6>
A circuit was configured in the same manner as in Example 3 except that the frequency of the pulse power output to the light emitting diode was 160 Hz. This circuit was referred to as Comparative Example 6.
<Comparative Example 7>
A circuit was configured in the same manner as in Example 3 except that the frequency of the pulse power output to the light emitting diode was 180 Hz. This circuit was referred to as Comparative Example 7.
<Comparative Example 8>
A circuit was configured in the same manner as in Example 3 except that the frequency of the pulse power output to the light emitting diode was 200 Hz. This circuit was referred to as Comparative Example 8.

<Comparative test 2 and evaluation>
The temperature of the light emitting diode and the load current when the light emitting diode was turned on were measured by the circuits of Examples 3 to 9 and Comparative Examples 1 to 8, respectively. The temperature of the light emitting diode was measured 1 minute after the start of lighting of the light emitting diode on the lower surface of the first heat radiating member of FIG. The results are shown in Table 2. In addition, the circuit whose temperature was 34 degrees C or less was set as the pass from the specification of the light emitting diode. Table 2 also shows the frequency and voltage of the Pal power and the resistance value of the limiting resistor.

As is apparent from Table 2, in Comparative Examples 1 to 3 in which the frequency of the pulse power output to the light emitting diode is less than 60 Hz, the load current is as small as 106.7 to 106.8 mA, and the temperature of the light emitting diode is 33.2. Although it was as low as ˜33.3 ° C., the light emitted from the light-emitting diode was seen in the eyes as discontinuous light (flashing light). In Comparative Examples 4 to 8 where the frequency of the pulse power output to the light emitting diode exceeded 100 Hz, the light emitted from the light emitting diode was seen as continuous light, but the load current increased to 107.5 to 108.6 mA. The temperature of the light emitting diode increased to 34.2 to 34.8 ° C., and the light emitting diode exceeded the specified value (34 ° C.), resulting in a large amount of heat generation. On the other hand, in Examples 3-9 in which the frequency of the pulse power output to the light emitting diode is in the range of 60-100 Hz, the load current is 106.8-107.2 mA, Comparative Examples 2-4, and Comparative Examples 5-5. The intermediate value of 9 was shown, the temperature of the light emitting diode was 33.4 to 34.0 ° C. and below the specified value (34 ° C.), and the light emitted from the light emitting diode was seen as continuous light.

  Note that the amount of heat generated by the light emitting diode increases as the frequency of the pulse power output to the light emitting diode increases, for the following reason. When pulse power is output to the light emitting diode, as shown in the oscilloscope photographs of FIGS. 12A to 12C, a sharp whisker-like overvoltage appears at the rising portion of each pulse voltage, and then decreases to a constant value. The area of the whisker-like overvoltage portion is proportional to an unnecessary load, that is, a heat generation amount. When the frequency is relatively low, such as 60 Hz (an oscilloscope photograph in FIG. 12A) or 100 Hz (an oscilloscope photograph in FIG. 12B), the area of the whisker-like overvoltage portion is relatively small. Although the frequency is small, for example, when the frequency is as high as 200 Hz (an oscilloscope photograph in FIG. 12C), the area of the whisker-like overvoltage portion increases, and the amount of heat generation increases.

10, 80, 100 Light emitting device for automobile 11 Light emitting diode 12, 82, 102 Lighting circuit 12a Input terminal of lighting circuit 13 Switching regulator 14, 84 Smoothing circuit 16, 106 Pulse power output circuit 17a, 17b Limiting resistor 20 Automotive (vehicle) )
20a Daylight on the right side 20b Daylight on the left side

Claims (4)

In a vehicle light emitting device including two or more light emitting diodes (11) mounted on a vehicle and a lighting circuit (12, 82, 102) for lighting these light emitting diodes (11),
The traveling speed of the vehicle is detected by a vehicle speed sensor,
The vehicle light-emitting device, wherein the lighting circuit (12, 82, 102) is configured to change the luminance of the light-emitting diode (11) based on a detection output of the vehicle speed sensor (15).   When the vehicle speed sensor (15) detects a vehicle speed greater than or equal to a predetermined value in the range of 60 to 100 km / hour, the lighting circuit (12, 82, 102) causes the light emitting diode (11) to emit light with 100% luminance, and the vehicle speed When the sensor (15) detects a vehicle speed less than a predetermined value in the range of 60 to 100 km / hour, the lighting circuit (12, 82, 102) reduces the luminance of the light emitting diode (11) to 40 to 70%. The vehicle light emitting device according to claim 1 configured as described above. The input terminal (12a) of the lighting circuit (12, 82, 102) is connected to a battery having a DC voltage of 9 to 30V,
The lighting circuit (12,82,102)
A switching regulator (13) for converting DC power input from the battery into pulse power of 30 kHz to 40 kHz;
A smoothing circuit (14, 84) for converting the pulse power converted by the switching regulator (13) into DC power;
A voltage changing circuit (20) for changing the voltage of the DC power converted by the smoothing circuit (14, 84) based on the detection output of the vehicle speed sensor (15);
A pulse power output circuit (16, 106) for converting the DC power output from the smoothing circuit (14, 84) by changing the voltage in the voltage changing circuit (20) into a pulse power of 60 to 100 Hz;
3. The vehicle light emission according to claim 1, further comprising: a limiting resistor (17 a, 17 b) for limiting the current of the pulse power converted by the pulse power output circuit (16, 106) and outputting the current to the light emitting unit (11). apparatus.   The light-emitting device for vehicles according to any one of claims 1 to 3, wherein the light-emitting diode (11) is a daylight (20a, 20b) or a headlight of the vehicle (20).