JP2006103404A - Lighting control circuit of vehicle lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To light a main semi-conductor light source even if a sub semi-conductor light source among a plurality of semi-conductor light sources having the main-sub relationship for a lighting condition becomes abnormal. <P>SOLUTION: When a high beam switch 40 is turned on and currents are fed through LED 12, 14 from a switching regulator 16, both LED 12 and LED 14 are lighted if a transistor 48 is turned on and a transistor 44 is turned off, and both ends of the LED 14 are released. If the LED 14 is broken on this occasion, the current passage of the LED 12 is cut off, the load of the switching regulator 16 enters a no-load state, and then an output voltage is increased. When the voltage of a line L exceeds the zener voltage of a zener diode Z1, a current is passed through the zener diode Z1, and a condenser C3 becomes charged. Then, transistors 52, 50 are turned on, and a high level voltage is applied to the gate of the transistor 44 through a diode D2. Furthermore, the transistor 44 is turned on compulsorily, and both ends of the LED 14 are short-circuited, and then the LED 12 is lighted. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lighting control circuit for a vehicular lamp, and more particularly, to a lighting control circuit for a vehicular lamp configured to control lighting of a semiconductor light source composed of a semiconductor light emitting element.

  2. Description of the Related Art Conventionally, a vehicular lamp using a semiconductor light emitting element such as an LED (Light Emitting Diode) as a light source is known, and this type of vehicular lamp has a lighting control circuit for controlling the lighting of the LED. Has been implemented.

  When configuring various lamps using LEDs, a master-slave relationship is set for two types of lamps having different lighting conditions, for example, a low beam headlamp and a bending lamp, or a low beam headlamp and a high beam headlamp. The main lamp and the sub lamp are connected in series with each other, the main lamp, for example, the low beam headlamp is lit at night, and the sub lamp, for example, the bending lamp, is required when the vehicle is Some lights only turn on when making a right or left turn.

  Further, as shown in FIG. 5, a light source block 58a constituting a low beam headlamp using a plurality of LEDs and a light source block 58b constituting a high beam headlamp using a plurality of LEDs are connected in series with each other, Both ends of the light source blocks 58a and 58b connected in series are connected to the switching regulator 114. When the low beam switch 202b is turned on, the transistor 206 is turned on and the switch 204 is turned on to connect both ends of the light source block 58b. When a short circuit occurs and only the light source block 58a is turned on and the high beam switch 202a is turned on, the transistor 206 is turned off and the switch 204 is turned off to open both ends of the light source block 58b. Turn on block 58b There are those like (see Patent Document 1).

JP 2004-136719 A (2nd to 4th pages, FIG. 1)

  In the prior art, since the current supply to the light source blocks 58a and 58b is controlled using the switching regulator 114, even when the light source blocks 58a and 58b are turned on, or only the light source block 58a is turned on. However, a prescribed current can be supplied to the light source blocks 58a and 58b, and each headlamp can be lit in a good state.

  However, since the light source block 58a and the light source block 58b are connected to each other in series, if the light source block 58b is disconnected when the light source block 58a is lit, the energization path of the light source block 58a is interrupted. The light source block 58a is turned off. Further, if the light source block 58b is disconnected before the low beam switch 202b is turned on, the energization path of the light source block 58a is already cut off even if the low beam switch 202b is turned on. Cannot be lit.

  The problem of the present invention has been made in view of the problems of the prior art, and its purpose is that even if a slave semiconductor light source becomes abnormal among a plurality of semiconductor light sources having a master-slave relationship with lighting conditions, The main semiconductor light source is turned on.

  To achieve the above object, in the lighting control circuit for a vehicular lamp according to claim 1, supply of current to the plurality of semiconductor light sources with a plurality of semiconductor light sources connected in series with different lighting conditions as loads. Current supply means for lighting a semiconductor light source belonging to at least one of the plurality of semiconductor light sources, and a semiconductor light source belonging to the other lighting condition of the plurality of semiconductor light sources, Switch means for short-circuiting or opening both ends of the semiconductor light source belonging to the other lighting condition in response to a lighting control signal for the semiconductor light source belonging to the other lighting condition, and an abnormality related to the semiconductor light source belonging to the other lighting condition In response to the abnormality detection means to detect and the abnormality detection output of the abnormality detection means, the switch means is forcibly short-circuited And a configuration in which a switch control means.

  (Operation) When the semiconductor light source belonging to one lighting condition is turned on, if the switch means opens both ends of the semiconductor light source belonging to the other lighting condition in response to the lighting control signal, it belongs to the other lighting condition. When the semiconductor light source is turned on and the switch means short-circuits both ends of the semiconductor light source belonging to the other lighting condition, the semiconductor light source belonging to the other lighting condition is turned off and only the semiconductor light source belonging to the one lighting condition is turned on. Before the semiconductor light source belonging to one lighting condition is turned on, an abnormality has already occurred in the semiconductor light source belonging to the other lighting condition, or when the semiconductor light source belonging to one lighting condition is turned on, When an abnormality occurs in a semiconductor light source belonging to a lighting condition, the switch means is forcibly short-circuited by the switch control means when the semiconductor light source belonging to one lighting condition is turned on. Since the bypass path for returning the current to the current supply means is formed by the switch means, the semiconductor light source (main semiconductor light source) belonging to one lighting condition can be turned on.

  That is, even if a slave semiconductor light source (semiconductor light source belonging to the other lighting condition) becomes abnormal among a plurality of semiconductor light sources having a master-slave relationship with lighting conditions, the main semiconductor light source (semiconductor light source belonging to one lighting condition) ) Can be turned on, which can contribute to driving safety.

  In the vehicle lamp lighting control circuit according to claim 2, the vehicle lamp lighting control circuit according to claim 1, wherein the abnormality detecting means includes the semiconductor light source belonging to the one lighting condition and the other lighting condition. When the voltage of the line connecting the semiconductor light source belonging to the above exceeds the abnormality determination value, an abnormality relating to the semiconductor light source belonging to the other lighting condition is detected.

  (Operation) When a semiconductor light source belonging to one lighting condition (main semiconductor light source) and a semiconductor light source belonging to the other lighting condition (secondary semiconductor light source) are both turned on, the semiconductor light source belonging to the other lighting condition is When the semiconductor light source belonging to one lighting condition (main semiconductor light source) is lit, the lighting control signal is turned on even though the semiconductor light source belonging to the other lighting condition is disconnected. If the switch means performs an opening operation according to the following, the current supply path of the semiconductor light source belonging to one of the lighting conditions is cut off, the load of the current supply means becomes no load, and the output voltage of the current supply means Rises. When the output voltage of the current supply means rises, the voltage of the line connecting the semiconductor light source belonging to one lighting condition and the semiconductor light source belonging to the other lighting condition also rises, and when the voltage of this line exceeds the abnormality determination value, An abnormality is detected for the semiconductor light source belonging to the other lighting condition, and the switching means forcibly short-circuits due to this abnormality detection, and a bypass path for returning the current from the semiconductor light source belonging to the one lighting condition to the current supply means is the switching means. Therefore, the semiconductor light source belonging to one lighting condition can be turned on immediately.

  In the lighting control circuit for the vehicle lamp according to claim 3, in the lighting control circuit for the vehicle lamp according to claim 1 or 2, the switch control means forcibly short-circuits the switch means. In addition, the short circuit operation of the switch means is maintained.

  (Operation) When the switch means is forcibly short-circuited by the switch control means, the short-circuit operation of the switch means is maintained, so that the semiconductor light source belonging to one lighting condition is prevented from hunting repeatedly turning on and off. be able to. That is, if the switch means is forcibly short-circuited and then immediately opened by the switch means, the energization path of the semiconductor light source belonging to one lighting condition is cut off, and the semiconductor light source belonging to one lighting condition is turned off again. To do. When the semiconductor light source belonging to one lighting condition is turned off, an abnormality relating to the semiconductor light source belonging to the other lighting condition is detected again, and the switch means is repeatedly forcibly short-circuited again. For this reason, holding the short-circuit operation of the switch means can prevent the semiconductor light source belonging to one lighting condition from being repeatedly turned on and off.

  As is apparent from the above description, according to the lighting control circuit for a vehicle lamp according to claim 1, even if the semiconductor light source belonging to the other lighting condition becomes abnormal, the semiconductor light source belonging to one lighting condition is turned on. Can contribute to driving safety.

  According to the second aspect, even if the semiconductor light source belonging to one lighting condition is turned off instantaneously due to the abnormality of the semiconductor light source belonging to the other lighting condition, the semiconductor light source belonging to one lighting condition can be turned on immediately. it can.

  According to the third aspect, it is possible to prevent the semiconductor light source belonging to one lighting condition from being repeatedly turned on and off.

  Next, embodiments of the present invention will be described according to examples. 1 is a circuit configuration diagram of a lighting control circuit for a vehicular lamp showing an embodiment of the present invention, FIG. 2 is a circuit configuration diagram when a plurality of LEDs belonging to the same lighting condition are connected in series, and FIG. FIG. 4 is a circuit configuration diagram when a plurality of light source blocks in which a plurality of LEDs belonging to the same lighting condition are connected in series are connected in parallel, and FIG. 4 is a circuit configuration diagram of a phase inversion circuit used for a high beam headlamp.

  In these drawings, a lighting control circuit 10 for a vehicular lamp is an element of a vehicular lamp (light emitting device), and a switch-on regulator 16, a switch circuit 18, and a switch control circuit 20 for two LEDs 12 and 14. The abnormality detection circuit 22 is provided.

  The LEDs 12 and 14 are connected in series as a semiconductor light source composed of a semiconductor light emitting element. The LEDs 12 and 14 have different lighting conditions and have a master-slave relationship. For example, the LED 12 is used as a low-beam headlamp (main lamp), and the LED 14 is used as a bending lamp (secondary lamp). Are connected to output terminals 24 and 26 of the switching regulator 16, and both ends of the LED 14 are connected to output terminals 28 and 30 of the switching regulator 16, respectively.

  The switching regulator 16 includes capacitors C1 and C2, a transformer T, a diode D1, a resistor R1, an NMOS transistor 32, and a control circuit 34. Both ends of the capacitor C1 are connected to power input terminals 36 and 38, One end of the capacitor C2 is connected to the output terminal 24, and one end of the resistor R1 is connected to the output terminal 30. The power input terminal 36 is connected to the plus terminal of the in-vehicle battery 42 via the low beam switch 40, and the power input terminal 38 is connected to the minus terminal of the in-vehicle battery 42.

  The switching regulator 16 converts the current flowing through the LEDs 12 and 14 into a voltage by the resistor R1 with the LEDs 12 and 14 as loads, and a switching signal, for example, several tens kHz to several hundreds kHz in the control circuit 34 based on the converted voltage. In order to generate a switching signal according to the frequency and to turn on / off the NMOS transistor 32 by this switching signal so that the DC voltage input between the power input terminals 36 and 38 becomes the light emission energy of the LEDs 12 and 14, the AC voltage is changed to the AC voltage. The converted AC voltage is smoothed by the diode D1 and the capacitor C2 to generate a DC current, and this DC current is supplied to the LEDs 12 and 14. Further, the switching regulator 16 controls the on / off operation of the NMOS transistor 32 by the control circuit 34 so that the current flowing through the resistor R1, that is, the current flowing through the LEDs 12 and 14, becomes a specified current. Then, the switching regulator 16 supplies power from the in-vehicle battery 42 and supplies current to at least the LED 12 among the LEDs 12 and 14 on the condition that the low beam switch 40 is turned on, and the low beam headlamp is turned on. It is supposed to be.

  The switch circuit 18 includes resistors R2, R3, R4, and an NMOS transistor 44 as switch means. One end of the resistor R2 is connected to the external output terminal 46, and one end of the resistor R3 is connected to the power source. One end of the resistor R4 is grounded, the connection point between the resistors R3 and R4 is connected to the gate of the NMOS transistor 44, the drain of the NMOS transistor 44 is connected to the output terminals 26 and 28, and the source is connected to the output terminal 30. Has been.

  The external output terminal 46 is connected to the collector of the vehicle-side NPN transistor 48 via a cable. The NPN transistor 48 is turned on and off in response to a signal from a sensor that detects that the steering angle of the steering wheel has exceeded a set angle when the vehicle turns left or right. That is, the NPN transistor 48 is turned on when the steering angle of the steering wheel exceeds the set angle, and is turned off at other times, and outputs a lighting control signal for controlling the lighting of the LED 14 to the external output terminal 46. It has become. When the steering angle of the steering wheel exceeds the set angle and the NPN transistor 48 is turned on, the voltage divided by the resistors R2 and R3 is applied to the gate of the NMOS transistor 44 as a gate voltage. Since this gate voltage is lower than the threshold voltage of the NMOS transistor 44, the NMOS transistor 44 is turned off and both ends of the LED 14 are opened. Thereby (on condition that the steering angle of the steering wheel exceeds the set angle), when the LED 12 is turned on, a current also flows through the LED 14, and the LED 14 is turned on together with the LED 12. That is, the bending lamp is turned on together with the low beam headlamp.

  On the other hand, when the steering angle of the steering wheel is equal to or smaller than the set angle and the NPN transistor 48 is turned off, the voltage divided by the resistors R3 and R4 is applied to the gate of the NMOS transistor 44 as a gate voltage. Since this gate voltage is higher than the threshold voltage of the NMOS transistor 44, the NMOS transistor 44 is turned on to short-circuit both ends of the LED 14. When the NMOS transistor 44 is turned on to perform a short-circuit operation, the current of the LED 12 bypasses the LED 14 and flows through the NMOS transistor 44, so that only the LED 12 is turned on and the LED 14 is turned off. That is, only the low beam headlamp is lit.

  The abnormality detection circuit 22 includes a Zener diode Z1 and a resistor R5 as abnormality detection means for detecting an abnormality relating to the LED 14. The cathode side of the Zener diode Z1 is connected to the output terminals 26 and 28 and the drain of the NMOS transistor 44. One end of the resistor R5 is grounded. The Zener voltage of the Zener diode Z1 is set to a value higher than the sum of the forward voltages of the LEDs 12 and 14, and when the LEDs 12 and 14 are in a normal state, the voltage applied to the Zener diode Z1 is less than the Zener voltage. Thus, no current flows through the Zener diode Z1.

  On the other hand, when both the LEDs 12 and 14 are lit, the LED 14 is disconnected, or when the NMOS transistor 44 is turned off and the both ends of the LED 14 are opened when the LED 14 is disconnected, The path of the current flowing through the LED 12 is cut off, the load of the switching regulator 16 becomes no load, and the output voltage of the switching regulator 16 increases. When the output voltage of the switching regulator 16 increases, the voltage of the line L connecting the LED 12 and the LED 14, that is, the drain voltage of the NMOS transistor 44 increases. If the voltage of the line L exceeds the Zener voltage as the abnormality determination value, an abnormality occurs in the LED 14, and a Zener current flows through the Zener diode Z1, and a voltage accompanying abnormality occurs at both ends of the resistor R5. The detection output is output to the switch control circuit 20.

  The switch control circuit 20 includes resistors R6, R7, R8, a capacitor C3, a diode D2, a PNP transistor 50, and an NPN transistor 52 as switch control means. One end of the resistor R6 is the anode side of the Zener diode Z1. , The emitter of the PNP transistor 50 is connected to the power supply, and the cathode side of the diode D2 is connected to the gate of the NMOS transistor 44.

  The capacitor C3 and the resistor R6 in the switch control circuit 20 constitute a low-pass filter. This low-pass filter has both ends of the capacitor C3 even when an abnormality is detected by the abnormality detection circuit 22 and a current flows through the resistor R5. The voltage is prevented from increasing instantaneously, and the NPN transistor 52 does not respond to a short-time disconnection.

  Specifically, when the LED 14 is normal, both the NPN transistor 52 and the PNP transistor 50 are off. On the other hand, a Zener current flows through the Zener diode Z1 due to the abnormality of the LED 14, and the capacitor C3 is charged by the Zener current. At this time, the charging voltage of the capacitor C3 increases according to a certain time constant. When the charging voltage of the capacitor C3 exceeds the threshold voltage of the NPN transistor 52, the NPN transistor 52 is turned on, the PNP transistor 50 is turned on, a current flows through the diode D2, and a current flows through the resistor R8. Flows. When the PNP transistor 50 is turned on and a current flows through the diode D2, both ends of the resistor R3 are short-circuited by the PNP transistor 50 and the diode D2, and the gate voltage of the NMOS transistor 44 becomes higher than the threshold voltage. As a result, the NMOS transistor 44 is forcibly turned on, and both ends of the LED 14 are short-circuited by the NMOS transistor 44.

  In addition, since the resistor R2 is inserted between the gate of the NMOS transistor 44 and the external output terminal 46, the gate voltage can be maintained at a high level regardless of the ON / OFF state of the NPN transistor 48.

  In addition, since the current is fed back to the base of the NPN transistor 52 through the resistor R8 when the PNP transistor 50 is turned on, the NPN transistor 52 remains in the on state even when the Zener current does not flow through the Zener diode Z1. As a result, the short-circuit operation of the NMOS transistor 44 can be maintained.

  Thus, in this embodiment, when the low beam switch 40 is turned on, current is supplied from the switching regulator 16 to the LEDs 12 and 14, the NMOS transistor 44 is in the on state, and both ends of the LED 14 are short-circuited. When the LED 12 is on, the LED 12 is turned on as a low beam headlamp.

  On the other hand, when the vehicle turns left or right as the vehicle travels and the steering angle of the steering wheel exceeds the set angle, the NPN transistor 48 is turned on, the NMOS transistor 44 is turned off, and both ends of the LED 14 are opened. Then, a current flows through the LED 14, and the LED 14 is turned on as a bending lamp.

  When the LED 14 is disconnected while the LEDs 12 and 14 are lit, or when the NMOS transistor 44 is turned off while the LED 14 is disconnected and both ends of the LED 14 are opened, the path of the current flowing through the LED 12 is interrupted. The load of the switching regulator 16 becomes no load, and the output voltage of the switching regulator 16 increases. When the output voltage of the switching regulator 16 rises, the voltage of the line L also rises. When the voltage of the line L exceeds the Zener voltage, a Zener current flows through the Zener diode Z1, and the voltage across the capacitor C3 becomes the threshold voltage of the NPN transistor 52. When exceeded, the NPN transistor 52 is turned on and the PNP transistor 50 is turned on. When the gate voltage of the NMOS transistor 44 exceeds the threshold voltage, the NMOS transistor 44 is forcibly turned on. When the NMOS transistor 44 is turned on, both ends of the LED 14 are short-circuited, and a bypass path for returning the current from the LED 12 to the switching regulator 16 is formed by the NMOS transistor 44, so that the LED 12 can be turned on immediately.

  According to this embodiment, even if the LED 14 (bending lamp as a secondary lamp) out of the LEDs 12 and 14 becomes abnormal, the LED 12 (low beam headlamp as a main lamp) can be lit, It becomes possible to contribute to safety.

  In the present embodiment, the single LEDs 12 and 14 are connected in series. However, as shown in FIG. 2, a plurality of LEDs 12 are connected in series or a plurality of LEDs 14 are connected. It is also possible to adopt a configuration in which these are connected in series with each other.

  Further, as shown in FIG. 3, a plurality of LEDs 12 connected in series to each other as a light source block 54, a plurality of light source blocks 54 connected in parallel, or a plurality of LEDs 14 connected in series to each other as a light source. A configuration in which a plurality of light source blocks 56 are connected in parallel can also be adopted as the block 56.

  In the present embodiment, the low beam headlamp and the bending lamp are used as lamps having different lighting conditions. However, the LED 12 can be used as a low beam headlamp and the LED 14 can be used as a high beam headlamp.

  In this case, as shown in FIG. 4, instead of connecting the external output terminal 46 to the vehicle-side NPN transistor 48, a high beam switch 58 and a phase inverting circuit 60 between the external output terminal 46 and the resistor R2 are provided. The inverting circuit 60 includes resistors R9, R10, and an NPN transistor 62. One end of the resistor R9 is connected to the high beam switch 58, and one end of the high beam switch 58 is connected to the positive terminal of the power source. The collector is connected to one end side of the resistor R2.

  When the LED 12 is used as a low beam headlamp and the LED 14 is used as a high beam headlamp, when the low beam switch 40 is turned on and the LED 12 is lit, the high beam switch 58 is turned on (the high beam switch is turned on). On the condition that the NPN transistor 62 is turned on and the NMOS transistor 44 is turned off, the opening operation of the NMOS transistor 44 allows the LED 14 to be lit as a high beam headlamp.

  On the other hand, when the LEDs 12 and 14 are lit, the LED 14 is disconnected, or the LED 14 is disconnected, the NPN transistor 62 is turned on, the NMOS transistor 44 is turned off, and both ends of the LED 14 are opened. Sometimes, the path of the current flowing through the LED 12 is interrupted, the load of the switching regulator 16 becomes no load, and the output voltage of the switching regulator 16 increases. As a result, as described above, when the output voltage of the switching regulator 16 increases, a Zener current flows through the Zener diode Z1, and when the voltage across the capacitor C3 exceeds the threshold voltage of the NPN transistor 52, the NPN transistor 52 At the same time, the PNP transistor 50 is turned on, and the NMOS transistor 44 is forcibly turned on. When the NMOS transistor 44 is turned on, both ends of the LED 14 are short-circuited, and a bypass path for returning the current from the LED 12 to the switching regulator 16 is formed by the NMOS transistor 44, so that the LED 12 can be turned on immediately.

  According to the present embodiment, even if the LED 14 (high beam headlamp) out of the LEDs 12 and 14 becomes abnormal, the LED 12 (low beam headlamp) can be turned on, which can contribute to driving safety. become.

  The LEDs 12 and 14 can be configured as light sources for various vehicle lamps such as stop & tail lamps, fog lamps, and turn signal lamps.

It is a circuit block diagram of the lighting control circuit of the vehicle lamp which shows one Example of this invention. It is a circuit block diagram when several LED which belongs to the same lighting conditions is connected in series. It is a circuit block diagram when a plurality of light source blocks in which a plurality of LEDs belonging to the same lighting condition are connected in series are connected in parallel. It is a circuit block diagram of the phase inversion circuit used for the headlamp for high beams. It is a circuit block diagram of the conventional lighting control circuit.

Explanation of symbols

10 Lighting control circuit for vehicle lamps 12, 14 LED
DESCRIPTION OF SYMBOLS 16 Switching regulator 18 Switch circuit 20 Switch control circuit 22 Abnormality detection circuit 32 NMOS transistor 34 Control circuit 40 High beam switch 44 NMOS transistor 48, 52 NPN transistor 50 PNP transistor Z1 Zener diode

Claims (3)

  Using a plurality of semiconductor light sources connected in series with different lighting conditions as a load, current supply to the plurality of semiconductor light sources is controlled, and the semiconductor light sources belonging to at least one of the plurality of semiconductor light sources are turned on The current supply means is connected in parallel to the semiconductor light source belonging to the other lighting condition among the plurality of semiconductor light sources, and is switched to the other lighting condition in response to the on / off control signal for the semiconductor light source belonging to the other lighting condition. Switch means for short-circuiting or opening both ends of the semiconductor light source belonging thereto, an abnormality detection means for detecting an abnormality relating to the semiconductor light source belonging to the other lighting condition, and the switch means in response to an abnormality detection output of the abnormality detection means A lighting control circuit for a vehicular lamp comprising switch control means for forcibly short-circuiting the lamp.   2. The lighting control circuit for a vehicle lamp according to claim 1, wherein the abnormality detection unit is configured such that a voltage of a line connecting the semiconductor light source belonging to the one lighting condition and the semiconductor light source belonging to the other lighting condition is an abnormality determination value. A lighting control circuit for a vehicular lamp characterized by detecting an abnormality related to the semiconductor light source belonging to the other lighting condition when the value exceeds.   The lighting control circuit for a vehicular lamp according to claim 1 or 2, wherein the switch control means holds the short-circuit operation of the switch means when the switch means is forcibly short-circuited. A lighting control circuit for a vehicular lamp.

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